Progress 06/01/11 to 05/31/16
Outputs
Target Audience:The target audience for the weed control research conducted under this project includes fruit, vegetable, and Christmas tree growers, Extension educators, chemical industry personnel, crop consultants, state regulators, and federal regulators. Information also is targeted to international cooperators. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Growers and Extension educators are involved in all field experiments. Experiments are conducted in grower fields when possible. Growers are encouraged to use new information and technology and to share their experiences with researchers and other growers. Undergraduate students are included in all field research. How have the results been disseminated to communities of interest?Information and data created from research is presented to the growers at public meetings. All experimental data is posted on the MSU website for public access. New information is published in popular journals and newspapers. Data is provideed to IR-4 and USEPA to support new pesticide registrations. MSU Extension publishes the bulletins: Weed control guide for vegetable crops, E-433, and the Michigan Fruit Mangement Guide, E-154, which contain current grower weed control recommendations. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
1. Weed control trials were conducted in fruit and vegetable crops. In apple, a combination of oxyfluorfen plus penoxsulam provided season-long suppression of most annual broadleaf and grass weeds. This combination was very effective against dandelion and horseweed. Isoxaben provided improved control of common lambsquarters, horseweed, eastern black nightshade, common ragweed, and prostrate knotweed. Several of these weeds are difficult to control with other residual herbicides. Indaziflam provided broad-spectrum control of most annual broadleaf and grass weeds for 8-12 weeks in apple. Improved weed control should result in at least a 1% apple yield increase, with return to growers of an additional $2.5 million per year. 2. New herbicide registrations were obtained for pendimethalin on caneberry and blueberry. A state label with shortened preharvest interval for halosulfuron on cucumbers was obtained. A Supplemental Section 3 label was obtained for pronamide on leaf lettuce. All of these new labels will result in greater yields and higher returns for Michigan fruit and vegetable growers. 3. Greenhouse trials supported earlier results of common purslane resistant to photosystem II herbicides. The resistance is somewhat erratic and has been difficult to verify. 4. Common ragweed collected from a Christmas tree plantation appears to be resistant to clopyralid. Initial screening indicates a high level of resistance.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2015
Citation:
Phillippo,C., Zandstra, B. 2015. Weed control in culinary herbs. WSSA Abstracts 55:237.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2015
Citation:
Zandstra, B. 2015. Bicyclopyrone for weed control in vegetable crops. NEWSS Abstracts 69:44.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2015
Citation:
Zandstra, B. 2015. New perspective on preemergence onion weed control. WSSA Abstracts 55:238.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2015
Citation:
Herbicide combinations for weed control in fruit crops. 2015. NCWSS Proceedings 70:154.
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Progress 10/01/14 to 09/30/15
Outputs
Target Audience:The target audience for weed control research includes fruit and vegetable growers, Extension Educators, processing company fieldmen, chemical company representatives, public officials, public media personnel, state and federal regulators, and international scientists. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided?Extension educators were included in all experiments in grower fields. Several growers received help and training in weed control methods to improve field practices. Undergraduate students were included in all activities. How have the results been disseminated to communities of interest?Results of registration projects are provided to IR-4 to support pesticide labeling. Results of herbicide trials are reported in MSU Horticulture Report 79, which is available on line. New labels and recommendations are included in E-154 , Michigan fruit management guide and E-433 Weed control guide for vegetable crops. A new publication Weed control in Christmas trees (E-3237) was published as a hard copy and is available on line. What do you plan to do during the next reporting period to accomplish the goals?Herbicide experiments will be conducted on fruit and vegetable crops to develop effective and innovative methods of weed control using all modes of action available. New herbicides will be tested for crop safety and weed control effectiveness. New registered uses will be explained in public meetings and in popular publications.
Impacts
What was accomplished under these goals?
1. Preemergence herbicides were used alone and in combinations on perennial fruit and vegetable crops to increase the weed control spectrum and avoid development of weed resistance to herbicides. In apples, the combination of sulfentrazone plus carfentrazone plus terbacil provided excellent control of wild carrot for over 8 weeks. Terbacil plus norflurazon controlled wild carrot for 12 weeks. Isoxaben plus pendimethalin provided 8 weeks control of white campion and perennial sowthistle. The combination of oxyfluorfen plus penoxsulam controlled alfalfa, birdsfoot trefoil and curly dock. In grape, sulfentrazone plus carfentrazone plus oryzalin and sulfentrazone plus carfentrazone plus indaziflam provided excellent control of field bindweed for 12 weeks. In asparagus, terbacil plus sulfentrazone provided complete control of wild carrot, horseweed, and wild radish for 8 weeks. Norflurazon plus metribuzin and flumioxazin plus terbacil provided excellent control of all weeds for 8 weeks. Combination of residual herbicides with different modes of action in perennial crops has improved control of persistent weeds and will increase crop yields and decrease weed and pest control expenses. Good weed control may result in a 10% increase in asparagus yield, with a total annual increase in return to Michigan growers of $2-4 million. 2. Forty six weed control experiments were conducted on fruit, vegetables, herbs, and Christmas trees. Twenty three residue and efficacy trials were conducted to support new registrations at USEPA. 3. Greenhouse experiments confirmed common purslane resistance to prometryn. Additional experiments are planned to complete the verification process. 4. Putative PSII resistant common purslane was collected from additional locations and is being tested in the greenhouse for PSII resistance.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2015
Citation:
Phillippo, C.J., Zandstra, B.H. 2015. Weed control in culinary herbs. WSSA Abstracts 55:237.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2015
Citation:
Zandstra, B.H., Phillippo, C.J. 2015. New perspective on preemergence onion weed control. WSSA Abstracts 55:238.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2014
Citation:
Phillippo, C.J., Zandstra, B.H. 2014. Weed control in Concord grape. WSSA Abstracts 54:311.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2014
Citation:
Phillippo, C.J., Zandstra, B.H. 2014. Weed control in vegetable crops with bicyclopyrone. NCWSS Proceedings 69:178.
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2014
Citation:
Zandstra, B.H. Phillippo, C.J. 2014. Weed control in edamame. NCWSS Proceedings 69:177.
- Type:
Journal Articles
Status:
Awaiting Publication
Year Published:
2015
Citation:
Kaya Altop, E., Mennan, H., Phillippo, C. Zandstra, B. 2015. Effect of burial depth and environmental factors on seasonal germination of bearded sprangletop (Leptochloa fusca (L.) Kunth ssp. Fascicularis (Lam.) N. Snow). Weed biology and management 15 (3): .
- Type:
Journal Articles
Status:
Under Review
Year Published:
2015
Citation:
Kaya Altop, E., Haghnama, K., Sariaslan, Phillippo, C., Mennan, H., Zandstra, B. 2015. Long-term perennial weed control strategies: economic analyses and yield effect in hazelnut (Corylus avellana). Crop Protection 34:
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Progress 10/01/13 to 09/30/14
Outputs
Target Audience: The target audience for weed control research includes fruit and vegetable growers, Extension Educators, processing company fieldmen, chemical company researchers and field representatives, journalists, state and federal regulators, and foreign scientists. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? Three Extension Educators were included in weed control experiments and discussions to expand their knowledge of vegetble weed control. Several growers hosted weed control experiments and were included in discussions of results. They can help educate other growers about new registrations and uses of herbicides. How have the results been disseminated to communities of interest? All field weed control experiments are summarized in MSU Horticulture Report 78, Weed control research on fruit and vegetable crops, December 1, 2014. The results of research are posted on-line at the MSU Department of Horticulture website. New registration and use information is included in crop production bulletins: Michigan Fruit Management Guide, MSU Extension Bulletin E-154, and Weed Control Guide for Vegetble Crops, MSU Extension Bulletin E-433. What do you plan to do during the next reporting period to accomplish the goals? Herbicide experiments will be conducted on various fruit, vegetable, and culinary herb crops to compare current and potential herbicide uses. Data collected will be used to educate growers on new uses, and to support additional herbicide registrations. Results will be shared with supporting commodity groups, regulatory agencies, pesticide manufacturers, and all other interested persons.
Impacts
What was accomplished under these goals?
What was accomplished. 1. As a result of our research, new labels were approved for several herbicide uses for fruit and vegetable crops. Linuron was labeled for celeriac, cilantro, dill, horseradish, parsley, peas, rhubarb, and edamame. The fomesafen label was expanded to include edamame, pea, pepper, tomato, pumpkin, and squash. The pendimethalin label was expanded to include green onions, and a separate state label allows a double rate on high-organic soils. S-metolachor was labeled for edamame. Prometryn was labeled for celeriac, okra, parsley, rhubarb, and dill. Clomazone was labeled for banana pepper with a state label. The oxyfluorfen onion label was modified for use in Michigan at higher rates at the onion one-leaf stage. Halosulfuron was labeled for caneberry and blueberry. Quinclorac was labeled for cranberry and rhubarb. Imazosulfuron was labeled for nutsedge control in pepper and tomato. Carfentrazone was labeled for hops. Sulfentrazone was labeled for use in blueberry, caneberry, and grape. Growers have adopted these new herbicide uses rapidly. Onion growers were able to prevent serious yield loss from ladysthumb (Polygonum persicaria) competition by use of oxyfluorfen at the onion one-leaf stage. This label increased grower returns by over $1 million as a result of increased yield. Linuron and prometryn labels for dill, cilantro, and parsley resulted in large reductions in hand labor for weed control and greater yields and profits. The clomazone label for banana pepper resulted in a 10-20% yield enhancement and reduced labor costs. 2. Forty four field weed control experiments were conducted on five fruit crops, three Christmas tree species, 23 vegetable crops, and nine culinary herbs. Results of these experiments are used to support new herbicide registrations. Data is shared with chemical companies, IR-4, state regulators, and USEPA. 3. Common purslane was grown in a greenhouse and tested for photosystem II resistance. Results indicate some level of resistance. Additional experiments are needed to confirm and verify resistance. 4. Another site of putative PS II resistance in common purslane in a celery field was identified.
Publications
- Type:
Conference Papers and Presentations
Status:
Published
Year Published:
2014
Citation:
Phillippo, C.J.,Zandstra, B.H.2014. Weed control in concord grape. WSSA Abstracts 54:311.
Zandstra, B.H., Phillippo, C.J. 2014. Maintaining raspberry weed free with clopyralid and other herbicides. WSSA Abstracts 54:312.
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Progress 01/01/13 to 09/30/13
Outputs
Target Audience: The target audience for horticultural weed control research includes: fruit growers, vegetable growers, educators, farm managers, processing company fieldmen, journalists, chemical company scientists, state and federal regulators, foreign scientists. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? Two technical assistants were trained in field herbicide research techiques. One technical assistant also was trained in use of Good Laboratory Practices for pesticide registrations. How have the results been disseminated to communities of interest? A printed report of all herbicide experiments will be published by December 1, 2013. It is presented to all interested chemical companies, growers, farm advisors, and government officials who have requested or need the information. The report also will be available on line. Reports of research results on individual crops and modified herbicide recommendations based on new data are presented to commodity research committees and to growers in public meetings. What do you plan to do during the next reporting period to accomplish the goals? Herbicide efficacy, crop safety, and crop residue experiemnts will be conducted on most major fruit and vegetable crops. The results will be available to the various users of the data by December 31, 2014.
Impacts
What was accomplished under these goals?
1. Several new herbicide uses were labeled in 2013. Indaziflam is now labeled for pome fruit, stone fruit and grapes. Flazasulfuron is labeled on grapes. A new formulation of napropamide is labeled on several fruit and vegetable crops. The isoxaben label was expanded to include bearing grapes and newly established grapes. The pendimethalin label was expanded to include preemergence application on green onions. The clopyralid label was expanded to include apple. Prostrate pigweed was confirmed to be resistant to terbacil in native spearment fields. The halosulfuron label was changed to reduce the preharvest interval to 21 days, which allowed for use of halosulfuron postemergence on machine harvested pickling cucumbers. 2. Growers have adopted these practices to inprove the efficiency of their operations. Potential changes in grower practicies based on 2013 and previous year's research include use of indaziflam on all fruit crops and isoxaben for use on recently planted trees, bushes, and vines.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2013
Citation:
Zandstra, B.H., Morse, S., Tocco, R.V., Morrice, J.J. 2013. Response of asparagus to repeated application of residual herbicides. HortTechnology 23(1):109-113.
Wei, L.L., Morrice, J.J., Tocco, R.V., Zandstra, B.H. 2013. Fraser fir tolerance and weed control with hexazinone plus sulfometuron-methyl. HortTechnology 23(3):294-300.
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Progress 01/01/12 to 12/31/12
Outputs
OUTPUTS: Several long-residual herbicides have been developed recently for use in tree fruit crops. These herbicides improve the potential for season-long weed control in perennial crops. Preemergence herbicides were applied in November 2011 and April 2012 to 6-year-old dwarf apple trees. Glyphosate at 1.35 pounds per acre was added to all treatments to kill emerged weeds. No injury to apple trees was apparent from any treatment. Fall applied flumioxazin at 0.383 pounds per acre suppressed most weeds into July. Flumioxazin did not control dandelion and white clover. Barnyardgrass and large crabgrass were controlled through June but germinated in July. Fall panicum and yellow foxtail germinated in August. Horseweed control was maintained all season by fall and spring applications of flumioxazin plus glyphosate. Fall-applied indaziflam at 0.065 pounds per acre suppressed most annual broadleaves and grasses through August. Fall-applied indaziflam did not control white clover or dandelion. It maintained control of large crabgrass and yellow foxtail into September. Spring-applied indaziflam controlled dandelion. Fall-applied isoxaben at 1 pound per acre did not control annual bluegrass, and it was weak on common groundsel, common lambsquarters, dandelion, and white clover. Spring applied isoxaben was more effective for broadleaf weed control. It was weak against annual grasses. Fall applied flazasulfuron at 0.045 pound per acre was weak against annual bluegrass and horseweed. It controlled dandelion until July 1. It lost control of annual grasses by September. Spring applied flazasulfuron controlled dandelion all season. Fall applied oxyfluorfen plus penoxsulam at 1.5 pound per acre suppressed all weeds except dandelion until July 1. Horseweed, white clover, barnyardgrass and large crabgrass emerged in July. Spring-applied oxyfluorfen plus penoxsulam at 1.5 pounds per acre was slightly more effective than fall-applied oxyfluorfen plus penoxsulam. Large crabgrass emerged in late July in all oxyfluorfen plus penoxsulam plots. Fall applied rimsulfuron at 0.063 pound per acre suppressed most annual weeds until July. By late July common mallow, dandelion, horseweed, prostrate knotweed, and common groundsel had emerged. Spring applied rimsulfuron was more effective against most annual weeds. Fall and spring-applied terbacil at 2.4 pounds per acre provided excellent control of all annual weeds except common groundsel. In late July, large crabgrass germinated in the terbacil treatments. Wild carrot was difficult to control with most herbicides. Oryzalin at 3 pounds plus rimsulfuron at 0.063 pounds per acre provided good control through July. Pendimethalin at 3.8 pounds plus rimsulfuron at 0.063 pounds per acre also was effective. Flazasulfuron at 0.045 pounds and terbacil at 2.4 pounds per acre provided good wild carrot control. PARTICIPANTS: Bernard Zandstra set up experiments, applied herbicides, and conducted evaluations of all experiments. Jarrod Morrice maintained experiments, took yields, and analyzed results through statistical analysis. He also prepared final reports, and participated in public presentations of the results. TARGET AUDIENCES: The primary target audience for apple weed control studies is apple growers. Other target audiences are county Extension educators and representatives of chemical manufacturing companies and distributors. PROJECT MODIFICATIONS: There are no major changes in the activities planned for this project in 2013.
Impacts
Improved weed control in apples will result in a 5% increase in marketable yield of apples. Apples are a $130 million crop in Michigan. A 5% increase in value of the crop is $1.5 million additional income to apple growers.
Publications
- Tocco, R.V., Zandstra, B.H. 2012. Annual and perennial weed control in tree fruit with indaziflam, flumioxazin, rimsulfuron, halosulfuron, and flazasulfuron. WSSA Abstracts 52:205.
- Morrice, J.J., Zandstra, B.H. 2012. Weed control in apple with old and new herbicides. NCWSS Proceedings 67.
- Zandstra, B.H., Morrice, J.J. 2012. Pyroxasulfone for weed control in vegetable crops. NCWSS Proceedings 67.
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Progress 01/01/11 to 12/31/11
Outputs
OUTPUTS: Primocane-bearing raspberries are the preferred varieties for many growers. The plants are mowed to the ground in late fall or early spring. Berries are produced in late summer and fall on first year primocanes. Preemergence herbicides for fall-bearing raspberries are applied to the soil over the mowed rows in late fall or early spring. Raspberry herbicide experiments were conducted in 2008-2011. Preemergence herbicides were applied in April 2008, 2009, and 2010 to a mature planting of Heritage, and in 2011 to a second year planting of Caroline. Postemergence treatments were applied in early and late June, either over the top of the rows or as a directed spray to the base of the plants. Diuron at 3 pounds per acre and terbacil at 2 pounds per acre were safe on raspberry and controlled most annual weeds. Both herbicides suppressed quackgrass until mid-July. Terbacil controlled white campion and diuron provided partial control of white campion. Mesotrione at 0.188 pound per acre caused shortened canes and reduced yield. Rimsulfuron at 0.125 pounds per acre reduced primocane growth slightly and reduced yield one year. Rimsulfuron controlled most annual weeds. Flumioxazin at 0.196 pounds per acre caused slight raspberry stunting and reduced yields in 2011. Indaziflam at 0.065 pounds per acre caused slight reduction in primocane growth but yields were not reduced. Halosulfuron at 0.047 or 0.094 pounds per acre preemergence or directed postemergence was safe on raspberry and controlled most annual broadleaves, including rough fleabane. Clopyralid at 0.25 pounds per acre broadcast postemergence over canes or directed to the base of plants in mid-season was safe on raspberry and controlled rough fleabane and Canada thistle. Clopyralid caused some raspberry leaf curling, but clopyralid plots had high raspberry yields in all years. Results of these studies have been presented in grower meetings and regional professional meetings. Results also have been shared with individual growers. Use of effective and crop-safe herbicides resulted in greater marketable yields of raspberries. PARTICIPANTS: Bernard Zandstra, PI: planned the experiments and made field evaluations. Rodney Tocco: applied treatments, supervised harvests, and conducted statistical analysis of results; he also prepared final reports for distribution to the industry. TARGET AUDIENCES: The target audience for this research is commercial raspberry growers. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The most effective treatments had a 10 percent or greater yield increase. With average yield of 5000 pounds per acre, a 10 percent increase is 500 pounds. At $6.00 per pound the increase in return is $3,000 per acre.
Publications
- Herrmann, C.M., Zandstra, B.H. 2011. Postemergence weed control in snap bean, carrot, and lettuce using a precision-guided flame weeder. WSSA Abstracts 51:191.
- Herrmann, C.M., Zandstra, B.H. 2011. Preemergence and postemergence herbicides for maximum weed control in dry bulb onion. WSSA Abstracts 51:189.
- Tocco, R.V., Zandstra, B.H., Herrmann, C.M. 2011. Control of perennial weeds in old blueberry plantings. WSSA Abstracts 51:146.
- Tocco, R.V., Zandstra, B.H. 2011. Herbicide programs for perennial ever-bearing and spring bearing strawberry grown on bare soil. NCWSS Proceedings 66:210.
- Zandstra, B.H. 2011. Postemergence weed control In Christmas trees. Great Lakes Christmas tree Journal 6(2):12-15.
- Zandstra, B.H., Tocco, R.V. 2011. Preemergence and postemergence herbicides for primocane-bearing raspberry. NCWSS Proceedings 66:211.
- Zandstra, B.H., Wei, L.L., Tocco, R.V., Herrmann, C.M. 2011. Preemergence weed control options in Christmas trees. Great Lakes Christmas Tree Journal. 6(1): 4-7.
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Progress 01/01/10 to 12/31/10
Outputs
OUTPUTS: Weed control is a major expense for vegetable growers and it is especially difficult for organic growers and in crops with few or no registered herbicides. Flaming has been used in field crops for many years, but has had less success in vegetable production because of the potential for crop injury. A digital camera and computer guidance system with a shielded applicator was developed to flame between rows of vegetable crops. Propane was applied to snap beans, carrots, and lettuce at 10, 20, and 40 pounds per square inch pressure at speeds of 1, 2, and 4 miles per hour. Propane consumption ranged from 3.5 to 40.6 gallons per acre. With this system, over 90% of the field surface was flamed. Treatments were applied when snap beans had one expanded trifoliate leaf, carrots had one fern leaf, and lettuce had 3-4 leaves. Beans treated at 1 mile per hour were injured 23%. Injury increased with increased propane pressure. Treatment at 2 and 4 miles per hour did not cause serious crop injury, and only the 40.6 gallon per acre dose caused yield reduction. Carrots were more sensitive to thermal injury, but leaves regrew, and there was no reduction in yield from any of the flame treatments. Leaf lettuce was more sensitive to thermal injury than Romaine or head lettuce. All three types of lettuce suffered yield reduction from the flame treatments. Propane pressure of 20 and 40 pounds per square inch at speeds of 1 and 2 miles per hour controlled 64 to 94% of redroot pigweed and common lambsquarters. Common purslane and large crabgrass were controlled 89% at propane pressure of 40 pounds per square inch and 1 mile per hour. The most effective propane dose for both crop safety and weed control was 15 to 20 gallons per acre. Crop safety was greatest at 2 and 4 miles per hour. The burner was demonstrated to vegetable growers and others at field days in 2009 and 2010. Research reports were presented to grower groups at public meetings and in professional conferences. PARTICIPANTS: Bernard Zandstra: PI - Designed the machine, developed field testing protocols, gathered components to build machine, obtained funding to carry out the work. Philip Hill: Project cooperator - built the machine, modified the machine, offered advice on improvements. Steve Marquie: Project cooperator - programmed the computer, installed heat sensors and data recorders. Chad Herrmann: Graduate Research assistant - conducted experiments, analyzed data, prepared reports, presented information in public meetings. Partner organizations: Michigan Vegetable Council and Van Drunen Farms provided financial support for this burner project. TARGET AUDIENCES: The system was designed for organic vegetable growers, sustainable vegetable growers, and growers of vegetable crops with few or no registered herbicides. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Use of the flamer will reduce weeding costs for vegetable growers who have few or no herbicides available for their crops, or who produce organic vegetables. The shielded and digitally guided burner will reduce weeding costs from $1000 per acre to less than $100 per acre, with a saving of $900 per acre. Reduction of soil disturbance during hand weeding or cultivation will reduce new weed emergence. With several thousand acres of organic production in the state, the system can save over $1 million annually in weed control costs for vegetable growers.
Publications
- Herrmann, C.M., Zandstra, B.H. 2010. Postemergence propane flaming for non-chemical weed control in snap bean and carrot. WSSA Abstracts 50:423.
- Herrmann, C.M., Zandstra, B.H. 2010. New postemergence herbicides improve weed control in onion. WSSA Abstracts 50:418.
- Herrmann, C.M., Zandstra, B.H. 2010. A precision guided shielded sprayer for postemergence weed control in carrot and lettuce. NCWSS Proceedings 65:111.
- Herrmann, C.M., Zandstra, B.H. 2010. Avoiding crop injury and maximizing yield with preemergence and postemergence herbicides in onion. NCWSS Proceedings 65:113.
- Tocco, R.V., Herrmann, C.M., Zandstra, B.H. 2010. New herbicides for weed control in highbush blueberry. NCWSS Proceedings 65:137.
- Wei, L.L., Zandstra, B.H., Tocco, R.V., Herrmann, C.M. 2010. Chemical mowing of cover crops and weeds with glyphosate, clopyralid, and fluazifop for vegetation management in Fraser fir. NCWSS Proceedings 65:36.
- Wei, L.L., Zandstra, B.H., Tocco, R.V., Herrmann, C.H. 2010. White clover, hard fescue, and perennial rye cover crops for weed suppression in Fraser Fir. NCWSS Proceedings 65:119.
- Zandstra, B.H., Tocco, R.V., Herrmann, C.M. 2010. Developments in weed control in lettuce. NCWSS Proceedings 65:136.
- Zandstra, B.H., Tocco, R.V. 2010. Weed control in apple with flumioxazin, mesotrione, rimsulfuron, saflufenacil, and sulfentrazone. WSSA Abstracts 50:340.
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Progress 01/01/09 to 12/31/09
Outputs
OUTPUTS: Tree fruit growers have used photosynthetic inhibitor herbicides for residual weed control for many years. Lack of rotation of mode of action has led to weed resistance and species shifts. Several new herbicides have been registered or are in development for pre- or postemergence weed control in tree crops. Experiments were conducted to determine weed control efficacy and crop injury of new herbicides on apples. Preemergence treatments were applied in fall, early April, or late May. Postemergence treatments were applied in June or July. Flumioxazin applied in fall at 0.383 lb/a plus glyphosate 0.43 lb/a provided essentially 100% control of all weeds until June 1, after which horseweed, white clover, wild carrot, birdsfoot trefoil, and perennial ryegrass emerged. The same treatment applied in early May maintained better control of horseweed, white clover, and perennial ryegrass through August 1, after which these weeds germinated. Good control of other grasses and broadleaves was maintained until September. Saflufenacil applied at 0.045 lb/a in mid-April gave good control of horseweed and most other broadleaves until August 1. It was weak on curly dock, dandelion, and mustards, and did not control grasses. Rimsulfuron applied at 0.064 lb/a in mid-April suppressed most broadleaves until early June, after which prostrate knotweed, alfalfa, curly dock, birdsfoot trefoil and redstem filaree emerged. Rimsulfuron applied in early May and reapplied in early June maintained better weed control through September 1. Sulfentrazone applied at 0.375 lb/a in April controlled common chickweed, prostrate knotweed, and common lambsquarters. It did not control grasses, red clover, and birdsfoot trefoil, and it was weak on alfalfa, dandelion, horseweed, and shepherd's purse. Mesotrione applied at 0.188 lb/a in April suppressed all broadleaves through June 1, but it did not control grasses. Terbacil applied at 2.4 lb/a in April controlled all weeds through July 1. Application of glyphosate at 0.43 lb/a or glufosinate at 1.04 lb/a in early June following various preemergence treatments extended control of all weeds except perennial ryegrass into September. None of the treatments caused visual injury to apple. PARTICIPANTS: Bernard Zandstra: PI - prepared experimental protocols, maintained contact with industry research committees and industry representatives, took observations and recorded experimental results in the field, presented data at public and professional meetings. Rodney Tocco: Research Assistant - Conducted field experiments, recorded and processed all data, supervised undergraduate students Sylvia Morse: Research Assistant - conducted pesticide registration research and maintained all registration research data; dealt with public and private organizations regarding registration research protocols and data Chad Herrmann: Graduate Assistant - conducted research on weed control in vegetable crops Ling Long Wei: Graduate Assistant - conducted weed control and cover crop research on Christmas trees Partner organizations include: MI Onion Committee; MI Asparagus Advisory Board; Celery Research Inc., MI Mint Industry Committee, MI Vegetable Council; These organizations provided support for project related research. Graduate and undergraduate students were included in all aspects of the research. TARGET AUDIENCES: Michigan fruit, vegetable and Christmas tree growers. Talks were presented at public meetings for various groups around Michigan. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Use of flumioxazin, mesotrione, or rimsulfuron plus glyphosate in the fall or early spring followed by glyphosate or glufosinate in June provided nearly 100% weed control throughout the growing season in apples. This could result in a 5% increase in yield and a $5 million per year increase in total return to growers.
Publications
- Herrmann, C., Zandstra, B. 2009. Preemergence weed control in onion with pendimethalin, flumioxazin, ethofumesate, dimethenamid-p, s-metolachlor, and propachlor. NCWSS Proceedings 64:48.
- Herrmann, C., Zandstra, B. 2009. A computer-guided flamer for postemergence weed control in carrot and snapbean. NCWSS Proceedings 64:110.
- Richardson, R., Zandstra, B. 2009. Weed control in Christmas trees with flumioxazin and other residual herbicides applied alone or in tank mixtures. Hort Technology 19(1):181-186.
- Richardson, R., Marshall, M., Uhlig, R., Zandstra, B. 2009. Virginia creeper and wild grape control in Fraser fir. Weed Technology 19(1):181-186.
- Tocco, R., Zandstra, B., Herrmann, C. 2009. Season-long weed control in tree fruit with preemergence and postemergence herbicides. NCWSS Proceedings. 64:163.
- Wei, L., Zandstra, B., Tocco, R., Herrmann, C. 2009. Christmas tree and weed response to herbicides applied in 1st and 2nd year Fraser fir. NCWSS Proceedings 64:106.
- Herrmann, C., Zandstra, B., Tocco, R. 2009. A precision guided, shielded propane flamer for postemergence weed control in vegetable crops. WSSA Abstracts 49:478.
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: Onion is a poor competitor and requires season-long weed control to obtain maximum yield. New herbicides have been registered for onion that may improve weed control while minimizing crop injury. Experiments were conducted in 2008 to develop usage patterns for several newly formulated and labeled onion herbicides. Cultivars planted were the northern pungent storage types Sherman, Santana, and Festival. One experiment consisted of a 3 X 5 factorial in which flumioxazin was applied at 0.064, 0.032, or 0.0 lb/acre alone or tank mixed with maximum labeled rates of pendimethalin ACS or EC, s-metolachlor, or dimethenamid-P. Applications were made at the 2 leaf stage and again at the 4 leaf stage. When flumioxazin was applied alone or tank mixed with pendimethalin ACS, there was no significant injury or yield loss in any of the cultivars, regardless of the rate of flumioxazin applied. In flumioxazin tank mixes with pendimethalin EC, s-metolachlor, or dimethenamid-P, all cultivars suffered significant height reductions, delayed development, and yield loss. In another experiment, flumioxazin applied at 0.032 lb/acre provided good preemergence control of several broadleaf species but did not provide preemergence control of yellow nutsedge or large crabgrass. Preemergence application of flumioxazin did not reduce onion stand or yield. In an experiment assessing crop tolerance and efficacy, oxyfluorfen SC or EC was applied at 0.031, 0.063, 0.125, or 0.188 lb/acre to onions at the 1 leaf stage. Identical applications were made again at the 2 and 3 leaf stages. The 0.188 lb/acre rate of oxyflurofen EC resulted in significant reductions in onion height, leaf number, and yield among all cultivars. Oxyfluorfen EC applied at the 1 leaf stage produced visual injury symptoms in Festival and Santana when applied at rates of .063 lb/acre greater. Goaltender applied at the 1 leaf stage to the same cultivars did not produce significant injury except at 0.188 lb/acre. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Use of flumioxazin, pendimethalin ACS, and oxyfluorfen SC for weed control in onion should improve yield 10%, which increases return to growers by $1 million per year.
Publications
- Zandstra, B., Ott, E. 2008. Weed control in machine-harvested pickling cucumbers. WSSA Abstracts 48:239.
- Cisneros, J., Zandstra, B. 2008. Flame weeding effects on several weed species. Weed Technology 22:290-295.
- Herrmann, C., Zandstra, B. 2008. Postemergence shielded flaming for weed control in vegetable crops. NCWSS Proceedings 63:56.
- Herrmann, C., Zandstra, B. 2008. Maximum weed control in onion using flumioxazin and oxyfluorfen. NCWSS Proceedings 63:118.
- Ott E., Zandstra, B. 2008. Potential new pre and postemergende herbicides for weed control in carrot. WSSA Abstracts 48:248.
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Progress 01/01/07 to 12/31/07
Outputs
Yellow nutsedge is a serious and persistent weed in onion. An experiment was conducted to compare several rates and timings of bentazon application on onion to control yellow nutsedge and obtain maximum onion yields. Bentazon was applied at 0.28, 0.56 and 1.12 kg/ha either 2 or 4 times, beginning at the 2 or 3 leaf stages of onion. The maximum total amount of bentazon applied per plot was 2.24 kg/ha. The onion cultivars Highlander, Nebula and Yellow Sweet Spanish were planted. Bentazon at 0.28 kg/ha applied 4 times beginning at the onion 2 leaf stage gave only 50 percent yellow nutsedge control which resuled in yield reduction of Nebula, Highlander and Yellow Sweet Spanish. Bentazon at 0.56 kg/ha applied 4 times beginning at the onion 2 leaf stage gave 70 percent yellow nutsedge control and good Nebula yield, but reduced Highlander and Yellow Sweet Spanish yields. Addition of crop oil concentrate to bentazon at 0.56 kg/ha increased yellow nutsedge control to 80 percent
when treatments began at the 3 leaf stage, which resulted in good Nebula yield, but reduced Highlander and Yellow Sweet Spanish yield. Bentazon at 1.12 kg/ha applied twice beginning at the 2 leaf stage gave 80 percent yellow nutsedge control and good yield of Nebula and Highlander, but reduced yield of Yellow Sweet Spanish. Bentazon 1.12 kg/ha applied twice beginning at the 3 leaf stage provided only 50 percent yellow nutsedge control, resulting in significantly reduced yield of Nebula, Highlander and Yellow Sweet Spanish. Addition of crop oil concentrate to bentazon at 1.12 kg/ha improved yellow nutsedge control slightly, but did not affect crop injury or yield significantly.
Impacts
Effective yellow nutsedge control will improve onion yield by 10-15 percent. This will result in an increase in value for Michigan onion producers of over $1 million per year.
Publications
- Uhlig, R., Bird, G., Richardson, R., Zandstra, B. 2007. Soil fumigants to replace methyl bromide for weed control in ornamentals. HortTechnology 17(1):111-114.
- Zandstra, B., DeKryger, T. 2007. Arsenic and lead residues in carrots from foliar applications of monosodium methanearsonate:a comparison between mineral and organic soils, or from soil residues. Food Additives and Contaminants 24(1):34-42.
- Marshall, M., Zandstra, B., Richardson, R. 2007. Herbicide alternatives for atrazine and simazine in Christmas tree plantations. WSSA Abstracts 47:51.
- Ott, E., Herrmann, C., Zandstra, B. 2007. Pre and postemergence weed control in culinary herbs. NCWSS Abstracts 62:168.
- Zandstra, B., Ott, E. 2007. Bentazon for postemergence weed control in onion. NCWSS Abstracts 62:158.
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Progress 01/01/06 to 12/31/06
Outputs
Greenhouse and laboratory studies were conducted to evaluate the response of eastern black nightshade, smooth groundcherry and clammy groundcherry seeds to halosulfuron, trifloxysulfuron and rimsulfuron. Weed seeds were collected from various locations in Michigan in 2002, the seeds were extracted from the fruit and stored at minus 20C for 2 months and then maintained at 5C until planting. Eastern black nightshade seeds were treated with 1 percent sodium hypochlorite for 8 minutes and then rinsed with water for 24 h prior to planting. Fifty seeds of each species were planted in 10 cm pots filled with loamy sand soil. Halosulfuron (0.05 and 0.1 kg/ha), trifloxysulfuron (0.005 and 0.01 kg/ha), rimsulfuron (0.035 and 0.07 kg/ha) were applied one day after planting. Eastern black nightshade germination was recorded at 5, 14 and 28 days after treatment; then the plants were cut, dried and weighed. Clammy groundcherry and smooth groundcherry plants were counted at 7, 14 and
40 days after treatment; then the plants were cut, dried and weighed. Trifloxysulfuron at 0.005 and 0.01 kg/ha and rimsulfuron at 0.07 kg/ha treatments caused higher eastern black nightshade germination than the control at 14 days after treatment; however, they were not different at 28 days after treatment. All treatments resulted in lower eastern black nightshade dry weight, except halosulfuron at 0.05 kg/ha and trifloxysulfuron at 0.005 kg/ha which were not different from the control. Smooth groundcherry germination was not affected by any of the herbicides at 14 days after treatment, but rimsulfuron at 0.07 kg/ha treated seeds had 67 percent germination at 40 days after treatment, compared to the control with 46 percent. Results for clammy groundcherry differed between trials. In the first trial, trifloxysulfuron at 0.01 kg/ha had the highest germination at 14 and 40 days after treatment. In another trial, trifloxysulfuron at 0.21 kg/ha had the lowest germination. These studies
suggest that the sulfonylurea herbicides may stimulate nightshade and groundcherry seed germination. The germination response to these herbicides changed over time which suggests that other factors are involved in the stimulation process.
Impacts
Solanaceous weeds are an increasing problem in many vegetable crops. Understanding their biology and germination responses to herbicides should greatly improve the opportunities for control. More effective nightshade and groundcherry control could result in a $1 million increase in total annual return for Michigan tomato and pepper growers.
Publications
- Uhlig, R.E., Zandstra, B.H. 2006. Stimulation of germination of eastern black nightshade, smooth groundcherry and clammy groundcherry seeds with sulfonylurea herbicides. NCWSS Abstracts 61:174.
- Zandstra, B.H., Ott, E.J. 2006. Long-term weed control in asparagus. NCWSS Proceedings 61:126.
- Mennan, H., Zandstra, B.H. 2006. The effects of depth and duration of seed burial on viability, dormancy, germination and emergence of ivyleaf speedwell. WeedTechnology 20:438-444.
- Richardson, R.J., Zandstra, B.H. 2006. Evaluation of flumioxazin and other herbicides for weed control in gladiolus. WeedTechnology 20:394-398.
- Ott, E.J., Zandstra, B.H. 2006. Season-long weed control in solaneceous crops. NCWSS Proceedings 61:130.
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Progress 01/01/05 to 12/31/05
Outputs
Flumioxazin was recently registered for weed control in onion. It controls several weeds, including common lambsquarters, eastern black nightshade, ladysthumb, redroot pigweed, and spotted spurge. Flumioxazin may injure onions under some conditions. Experiments were conducted to determine herbicide rate, timing, and tank mix combinations for safe and effective use of flumioxazin on onion. Flumioxazin was applied to onion pre- or postemergence alone or in tank mixes. Onions were evaluated for visual injury and yield. Flumioxazin at 0.018 kg/ha plus pendimethalin 3.8 ACS at 2.24 kg/ha preemergence and again at the 2 leaf stage and 4-5 leaf stage caused no crop injury and gave excellent yield. The same rate of flumioxazin plus pendimethalin 3.3 EC at 2.24 kg/ha at the 2 and 4-5 leaf stages resulted in significant crop injury and yield reduction. Flumioxazin at 0.036 kg/ha applied in tank mixes with dimethenamid-P at 1.1 kg/ha at the 2 or 4-5 leaf stages caused yield
reduction. Flumioxazin 0.036 kg/ha applied alone between applications of dimethenamid-P at 1.1 kg/ha and pendimethalin 3.3 EC at 2.24 kg/ha alone at the 2 and 4-5 leaf stages, respectively, did not reduce yield. Flumioxazin at 0.036 kg/ha applied at the 2 and 4-5 leaf stages in tank mixes with oxyfluorfen 2 EC or oxyfluorfen 4 L at 0.035 or 0.071 kg/ha did not reduce yield. The same combinations plus clethodim at 0.14 kg/ha plus 0.5 percent nonionic surfactant caused yield reduction. When flumioxazin at 0.036 kg/ha was applied between the two applications of oxyfluorfen at 0.071 kg/ha plus clethodim at 0.14 kg/ha plus nonionic surfactant, there was no yield reduction. The tank mix of pendimethalin 3.3 EC at 2.24 plus oxyfluorfen 2 EC at 0.071 kg/ha plus clethodim at 0.14 kg/ha plus nonionic surfactant plus flumioxazin at 0.036 kg/ha resulted in almost total yield reduction. A combination of pendimethalin 3.8 ACS at 2.24 kg/ha plus oxyfluorfen 4 L at 0.071 kg/ha plus clethodim at 0.14
kg/ha plus nonionic surfactant plus flumioxazin at 0.036 kg/ha resulted in only slight yield reduction. Flumioxazin will be a valuable herbicide in onion production to control several broadleaf weeds. It should be alone or in tank mixes with water-based formulations of pendimethalin and oxyfluorfen to avoid crop injury.
Impacts
Weed control is a major expense in onion production. Effective use of flumioxazin and other herbicides should improve weed control and onion yield. A 5 percent increase in onion yield on 3,000 acres will result in a total increase in crop value of $500,000 per year.
Publications
- Arboleya, J.E., Masabni, J.G. and Zandstra, B.H. 2005. Identification of prehavest desiccants for use in onion production. HortTechnology 15(4):808-811.
- Mennan, H. and Zandstra, B.H. 2005. Effect of wheat cultivars and seeding rate on yield loss from Galium aparine (cleavers). Crop Protection 24:1061-1067.
- Mennan, H. and Zandstra, B.H. 2005. Influence of wheat seeding rate and cultivars on competitive ability of bifra (Bifora radians). Weed Technology 19:128-136.
- Pandian, V. and Zandstra, B.H. 2005. New herbicides to control nightshades in tomato. WSSA Abstracts 45:78.
- Particka, M.G. and Zandstra, B.H. 2005. Sweet corn tolerance of mesotrione. WSSA Abstracts 45:88.
- Zandstra, B.H. and Particka, M.G. 2005. Flumioxazin for postemergence weed control in onion. Proc. North Central Weed Science Society 60:192.
- Zandstra, B.H. and Particka, M.G. 2005. Asparagus tolerance of recurring residual herbicide applications over five years. WSSA Abstracts 45:281.
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Progress 01/01/04 to 12/31/04
Outputs
Asparagus is a perennial crop which is maintained without tillage for 15 to 20 years in Michigan. A limited choice of residual herbicides has resulted in continuous use of photosynthesis-inhibiting herbicides on very sandy soil, which may have an adverse effect on asparagus yields. An experiment was established in a mature asparagus field in 2000, and the same treatments were applied for five years to determine their effect on asparagus yield and weed control. Preemergence treatments were applied before crop emergence each spring, and postemergence treatments were applied during harvest in mid-June. Preemergence treatments were diuron 1.34 kg ai/ha followed by dicamba 0.56 kg/ha plus sethoxydim 0.21 kg/ha, diuron 1.34 kg plus metribuzin 0.67 kg/ha, norflurazon 2.24 kg/ha, flumioxazin 0.24 kg/ha, flumioxazin 0.45 kg/ha, sulfentrazone 0.28 kg/ha, halosulfuron 0.053 kg/ha, diuron 1.34 kg/ha followed by halosulfuron 0.053 kg/ha, terbacil 1.34 kg/ha, and untreated
preemergence followed by linuron 1.12 kg plus clopyralid 0.21 kg plus sethoxydim 0.21 kg/ha. Norflurazon consistently had lower yields than the other treatments. Norflurazon did not provide season-long weed control, and weed growth may have contributed to lower yields in following years. Diuron plus metribuzin had good weed control through each harvest season, but yields were reduced slightly. Yield suppression appeared to be a result of herbicide treatment. Flumioxazin, halosulfuron, and sulfentrazone gave excellent weed control, good crop tolerance, and good yield throughout the study.
Impacts
Weed control is a major expense and limiting factor in asparagus production. Use of the recently registered herbicides halosulfuron, s-metolachlor, and sulfentrazone will improve asparagus yield and long-term viability of fields. A five percent increase in yield from improved weed control on 16,000 acres of asparagus in Michigan will result in a total increase in crop value of $900,000 per year.
Publications
- Pandian, V. and Zandstra, B.H. 2004. Effect of temperature on germination of nightshade populations (Solanum spp) and groundcherry populations (Physalis spp). WSSA Abstracts 44:16.
- Pandian, V. and Zandstra, B.H. 2004. Variation in herbicide response among eastern black nightshade and hairy nightshade populations in Michigan. Proc. North Central Weed Science Society 59:91.
- Pandian, V. and Zandstra, B.H. 2004. Difference in herbicide response among nightshade and groundcherry species in Michigan. Proc. North Central Weed Science Society 59:50.
- Pandian, V. and Zandstra, B.H. 2004. Rimsulfuron carryover effects in cucumber, snapbean, and sugarbeet. Proc. North Central Weed Science Society 59:160.
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Progress 01/01/03 to 12/31/03
Outputs
Purple blotch (Alternaria porri) causes significant losses in Michigan onions. Experiments were conducted in 2001 and 2002 to investigate effects of chemical resistance activators and raised beds on A. porri incidence and onion yield. Onions were sprayed with acibenzolar-S methyl (ASM) 20 ppm, B-amino butyric acid (BABA) 10 mM, methyl jasmonate (MeJA) 10 mM, chlorothalonil 1.68 kg/ha alternated with copper hydroxide 0.84 kg/ha and mancozeb 1.09 kg/ha or MeJA 10 mM plus chlorothalonil 1.26 kg/ha alternated with maneb 1.34 kg/ha or iprodione 0.28 kg/ha. Treatments were applied at the 3, 5, and 7 leaf stages. One week after the last application, onions were sprayed with 8,500 spores/mL of A. porri added to a 1 percent solution of petroleum crop oil concentrate. Twenty-three days after inoculation in 2001 control plants had almost twice the number of lesions/plant as those treated with MeJA or fungicides. Plants treated with ASM or BABA were not different from the
untreated conrols. The treatments had no effect on total or marketable yields in 2001. Yields were reduced by MeJA and MeJA plus fungicide in 2002. Flat beds had lower plant stands than raised beds (34 and 22 percent reduction in stand) 40 days after planting in 2001 and 2002, respectively. Disease severity was higher on flat beds at 100 days after planting. Raised beds had greater total yields both years.
Impacts
Fungicides for purple blotch control are a major expense for onion growers. If growers can induce disease resistance by application of resistance activators, and plant onions on raised beds, they can reduce fungicide expense and increase yields by 15 percent. If this growing system is adopted on 10 percent of Michigan onion acres, gross returns could increase $500 per acre, or $150,000 for the state.
Publications
- Richardson, R.J. and Zandstra, B.H. 2003. Identification and management of Inula britannica in Michigan nurseries. HortScience 38(5):686-687.
- Arboleya, E.E., daRocha, A., Widders, I.E., Zandstra, B.H. and Hammerschmidt, R. 2003. Effect of chemical resistance activators on purple blotch disease, yield and quality of three onion cultivars. Proc. 4th National IPM Symposium, Indianapolis, IN. 35-36.
- Arboleya, J.E., Masabni, J.G., Particka, M.G. and Zandstra, B.H. 2003. Foliar desiccation of onions with herbicides. WSSA Abstracts 43:43.
- Arboleya, J.E., Zandstra, B.H., daRocha, A.B., Widders, I.E. and Hammerschmidt, R. 2003. HortScience 38(5):768.
- Cisneros, J.J. and Zandstra, B.H. 2003. Alternative herbicides in carrot production. WSSA Abstracts 43:42.
- Richardson, R.J., Carlson, E.J., Dudek, T.A. and Zandstra, B.H. 2003. Invasive weed problems in Michigan nurseries and potential control methods. WSSA Abstracts 43:61.
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Progress 01/01/02 to 12/31/02
Outputs
Onions are often delayed in maturity as a result of adverse weather and uncontrolled weeds. The objective of this study was to evaluate the effects of different compounds on onion and weed foliage desiccation and on stored bulb quality. Onion cultivar Hustler was planted on May 3, 2001 on Houghton Muck soil. Desiccation treatments were applied on September 4 when 50-70 percent of onion leaves were down but still green: paraquat 0.56 kg ai/ha plus Silwet L-77 0.5 percent v/v; endothal 1.12 kg/ha plus Bronc (AMS) 2.5 percent v/v plus Silwet L-77 0.5 percent v/v; diquat 0.56 kg/ha plus Silwet L-77 0.5 percent v/v; carfentrazone 0.22 kg/ha plus Silwet L-77 0.5 percent v/v; carfentrazone 0.22 kg/ha plus pelargonic acid 5 percent v/v; glufosinate 0.49 kg/ha plus Bronc 2.5% v/v plus Silwet L-77 0.5 percent v/v; and untreated. Diquat caused excellent onion and weed desiccation but resulted in only 43 percent of good bulbs after 21 weeks of storage. Carfentrazone was very
effective for desiccation of onions and weeds, but reduced quality of bulbs in storage to 67 percent. Paraquat and glufosinate caused good desiccation but resulted in 85 percent good bulbs in storage. Endothal had good foliar desiccation, and 91 percent of bulbs were good after storage, which was similar to the untreated control that had 90 percent good bulbs.
Impacts
Reduction in pesticide application rate should result in less pesticides in soil, air, and water. New herbicides and a more efficient sprayer may result in less use of linuron on carrot.
Publications
- Arboleya, J.E., daRocha, A.B., Widders, I.E., Zandstra, B.H. and Hammerschmidt, R. 2002. Greenhouse study of biological induction of resistance in onion against Alternaria porri. Phytopathology 92(6):S4.
- Arboleya, J.E. and Zandstra, B.H. 2002. Effect of flat and raised beds, irrigation and variety on yield and quality of onion. Internat. Hort. Congress Abstracts 16:573.
- Richardson, R.J., Zandstra, B.H., Carlson, E.J. and Dudek, T.A. 2002. Inula Britannica in Michigan nurseries and potential control methods. Proc. North Cent. Weed Sci. Soc. 57:.
- Richardson, R.J., Zandstra, B.H. and Masabni, J.G. 2002. Response of Fraser fir and persistent weeds to preemergence and postemergence herbicides. Proc. North Cent. Weed Sci. Soc. 57:.
- Particka, M.G., Masabni, J.G. and Zandstra, B.H. 2002. Weed control in orchards using preemergence and postemergence herbicides. Proc. North Cent. Weed Sci. Soc. 57:.
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Progress 01/01/01 to 12/31/01
Outputs
Preemergence and postemergence herbicide trials were conducted in the field on carrot on sand. In the preemergence trial, flumioxazin at 0.001 lb ai/acre did not injure carrot, but did not give sufficient weed control. Flumioxazin at 0.005 or 0.01 lb caused some stunting of carrot but gave better weed control. In the postemergence trial, flumioxazin was marginally safe at 0.031 and 0.047 lb ai. Carrot yield was reduced slightly at these rates, but weed control was acceptable. Flumioxazin may be safe on carrots at rates of 0.024-0.31 lb postemergence. Other herbicides that had some safety on carrot in the field were oxyfluorfen, flufenacet, and mesotrione. Preemergence and postemergence herbicide trials were conducted in the greenhouse. Carrot had good tolerance for flumioxazin at 0.001 or 0.005 lb preemergence, and at 0.02 to 0.06 lb postemergence. Carrots also had good tolerance for oxyfluorfen preemergence and postemergence. Azafenidin, carfentrazone, and
sulfentrazone caused unacceptable stand reduction and carrot injury.
Impacts
Reduction in pesticide application rate should result in less pesticides in soil, air, and water. New herbicides and a more efficient sprayer may result in less use of linuron on carrot.
Publications
- Zandstra, B.H. and Masabni, J.G. 2001. New herbicides for weed control in asparagus. WSSA Abstracts 41:178.
- Cisneros, J.J. and Zandstra, B.H. 2001. Alternative weed control methods for carrot production in Europe and Michigan. Proc. NCWSS 56:90.
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Progress 01/01/00 to 12/31/00
Outputs
Carrots are an important fresh market and processing crop in Michigan. There are few herbicides registered for carrots. Linuron is the primary pre- and postemergence herbicide used on carrots in the United States. Experiments were conducted to identify other herbicides that are both safe on carrots and effective on weeds. Another objective was to improve the efficacy of linuron applied postemergence with a low-volume, air-assisted sprayer plus adjuvants so that linuron rates could be reduced. Flumioxazin at 0.01 lb ai/a caused severe injury to carrot when applied postemergence at 0.025 or 0.05 lb. Other herbicides that were moderately safe on carrots when applied postemergence included azafenidin, flumiclorac, oxyfluorfen, prometryn, and sulfentrazone. A low-volume, air-assisted sprayer with Proptec application heads applied linuron at 0.25, 0.5 and 1 lb in 5 gpa water with or without a silicone based surfactant to carrots heavily infested with yellow nutsedge.
Similar treatments were applied with a boom sprayer at 20 gpa. Linuron applied twice at 0.5 or 1 lb ai gave season-long suppression of yellow nutsedge. There was no difference between sprayers in yellow nutsedge control at any rate of linuron. The silicone surfactant improved yellow nutsedge control initially, but the improvement disappeared by the end of the season.
Impacts
Reduction in pesticide application rate should result in less pesticides in soil, air, and water. New herbicides and a more efficient sprayer may result in less use of linuron on carrot.
Publications
- Masabni, J.G., Zandstra, B.H. 2000. Physiological characteristics of linuron-resistant Portulaca oleracea. Weed Science 48:420-425.
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Progress 01/01/99 to 12/31/99
Outputs
Poor germination is a serious problem in snapbeans in Michigan. A greenhouse experiment was conducted to determine the sensitivity of four snapbean cultivars to preplant incorporated (PPI) and preemergence (PRE) herbicides. Three flats for each treatment were sown with 20 seeds each of Hystyle, Labrador, Minuette and Pureline 5402. The PPI treatments were metolachlor 1.12 and 2.24 kg ai/ha, trifluralin 1.12 kg/ha, and pendimethalin 1.68 kg/ha. The PRE treatments were metolachlor 1.12 and 2.24 kg/ha and pendimethalin 1.68 kg/ha. Plant counts were taken at 6, 9, 15, and 21 days after treatment (DAT). Shoot height, shoot fresh and dry weights, and root fresh and dry weights were measured at 21 DAT. At 6 DAT, Pureline 5402 and Hystyle had 34 and 47% germination, respectively, across all herbicide treatments, vs 83 and 73% for untreated plants. Labrador and Minuette had 71 and 63% germination, respectively, vs 85 and 75% for controls. At 15 DAT, Pureline 5402 and Hystyle
had 68 and 73% germination, vs 86 and 81% for untreated, and Labrador and Minuette had 83 and 80% germination vs 91 and 81%. At 21 DAT, Labrador had the greatest shoot height and weight and root weight, followed by Minuette and Hystyle. Pureline 5402 had the most injury for all shoot and root variables measured. All treatments slowed germination, but by 15 DAT there were no differences between any treatments and controls. Pendimethalin applied PPI or PRE caused the greatest reduction of all variables. Metolachlor at 1.12 kg/ha PPI or PRE and 2.24 kg/ha PRE had little effect on shoot height, fresh, or dry weights. All treatments resulted in reduction of root weights.
Impacts
(N/A)
Publications
- Masabni, J.G., Zandstra, B.H. 1999. A serine-to-threonine mutation in linuron resistant Portulaca oleracea. Weed Science 47:393-400.
- Masabni, J.G., Zandstra, B.H. 1999. Discovery of a common purslane (Portulaca oleracea) biotype resistant to linuron. Weed Technology 13:599-605.
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Progress 01/01/98 to 12/31/98
Outputs
MSMA is a selective, post-emergence herbicide registered for use in turf, cotton, nonbearing fruits and nuts, and non-crop areas. Some vegetable crops are tolerant of MSMA, and the low cost of the herbicide and its effectiveness against persistent weeds presents the potential for its application to unregistered food crops. The purpose of this study was to determine naturally-occurring levels of arsenic in carrot and the soil, and to compare those to levels after application of known amounts of MSMA. MSMA at 0, 0.5, 1.0, 2.0, and 4.0 lb ai/acre was applied to 5-6 inch carrots in 5 x 40 ft field plots. Soil samples were collected at planting and at harvest. MSMA did not cause phytotoxicity to carrots at any rate. Ten carrot roots were collected randomly from each plot 30 days prior to harvest and at harvest. Carrots were fractionated and tested for arsenic in both peel and core fractions. Total arsenic was tested by vapor generation atomic absorption spectroscopy. Soil
arsenic levels increased with applied MSMA but remained below the known average level (5.0 ppm) for soils in the U.S. Soil arsenic levels did not correlate with arsenic in the carrots. Arsenic levels in carrot cores taken at harvest correlated well with applied arsenic (r = 0.94, y = 0.39x + 0.02). Carrot peels gave similar results (r = 0.95, y = 0.79x + 0.03). The highest arsenic levels in carrots approached 3.0 ppm. Carrots sampled 30 days prior to harvest had approximately twice the levels found in the carrots at harvest. Arsenic did not affect carrot yields. The data indicate that arsenic in the carrots resulted from foliar application and not from soil uptake.
Impacts
(N/A)
Publications
- Zandstra, B.H., Chase, W.R. and Masabni, J.G. 1998. Interplanted small grain cover crops in pickling cucumbers. HortTechnology 8(3):356-360.
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Progress 01/01/97 to 12/31/97
Outputs
A common purslane (POROL) biotype collected from a carrot field in Michigan is highly resistant to linuron. DNA of the D1 protein of resistant (R) and susceptible (S) biotypes of POROL was sequenced and read manually, and by an Applied Biosystems Model 373A automated fluorescence sequencer. Both methods indicated a mutation of serine to threonine at position 264 in R-POROL. This mutation resulted in negative cross-resistance to bromoxynil, moderate resistance to diuron, metribuzin, terbacil and prometryn, and high resistance to atrazine, cyanazine and pyrazon. R-POROL had a slower growth rate than S-POROL. CO2 assimilation of R-POROL improved with increasing light intensity up to 2600 umol.m-2.s-1 and temperature up to 40C.
Impacts
(N/A)
Publications
- MASABNI, J.G., ZANDSTRA, B.H., YERKES, C.N. AND WELLER, S.C. 1997. Common purslane (Portulaca oleracea L.) Resistance to linuron is caused by serine to threonine mutation in the D1 protein. WSSA Abstracts 37:62.
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Progress 01/01/96 to 12/30/96
Outputs
Portulaca oleracea that was putatively resistant to linuron was collected from acarrot (Daucus carota) field in 1991 in Michigan. The field had been under continuous carrot cultivation for over 25 years. Laboratory and greenhouse experiments indicated that the ED50 for linuron for resistant (R) P. oleracea was 9.6 kg a.i./ha and less than 0.03 kg a.i./ha for susceptible (S) P. oleracea. The ED50 values for atrazine were greater than 179 kg a.i./ha for R-P. oleracea and less than 0.45 kg a.i./ha for S-P. oleracea. Fluorescence measurements indicated similar photochemical efficiency (Fv/Fm) in untreated R- and S-P. oleracea, but a differential response and recovery after linuron application. DNA sequencing of the psbA gene revealed a novel mutation from serine to threonine at codon 264.
Impacts
(N/A)
Publications
- CHASE, W.R., ZANDSTRA, B.H., RENNER, K. A., POWELL, G.E. 1996. Carryover effects of imazamox on vegetable crops. Proc. NCWSS 151 (Abstr.).
- MASABNI, J.G., ZANDSTRA, B.H., YERKES, C.N. WELLER, S.C. 1996. Linuron resistance in Portulaca oleracea. Proc. Second International Weed Control Congress, Copenhagen. 571-575.
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Progress 01/01/95 to 12/30/95
Outputs
Onion leaves should dry up and die at maturity under normal growing conditions. Under adverse conditions leaves do not dry naturally. Mechanical or chemical treatments are needed to desiccate leaves before harvest. Onions with about 50% of the leaves down (near maturity) were treated with herbicides, fertilizers, or inorganic salts to desiccate leaves and prepare the bulbs for mechanical harvest and storage. Some treatments included adjuvants. Onion leaves were rated visually for desiccation. Onions were harvested, placed in storage, and evaluated after several months. Paraquat 0.5 lb/a and diquat 0.25 lb/a desiccated onion leaves well but caused bulb decay in storage. Bromoxynil 1.0 lb/a, endothall 1.0 lb/a, and MYX 4801 4 gal/a gave fair desiccation and no adverse effects on bulbs in storage. Marginally effective or ineffective treatments included copper sulfate, 28% UAN, sodium borate, ammonium nitrate, ammonium chloride, calcium EDTA, sodium molybdate, potassium.
Impacts
(N/A)
Publications
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Progress 01/01/94 to 12/30/94
Outputs
Physical characteristics of linuron-resistant (RCOPU) and linuron-susceptible (SCOPU) common purslane were compared to determine anatomical and morphological differences between the biotypes. SCOPU seeds were 27% heavier than RCOPU seeds. Six hundred seeds of each biotype were germinated on filter paper in petri-dishes to test viability. The germination rates were 40% and 24% for the SCOPU and RCOPU, respectively. SCOPU was more vigorous and had greater fresh and dry weight than RCOPU up to 107 days after seeding (DAS). At 107 DAS, fresh weight (FW) of SCOPU plants was 8.5% greater than FW of RCOPU plants. At 43 DAS, SCOPU plants had an average of 45 leaves per plant, compared to 32 leaves per plant for RCOPU. Thick cross-sections (1-1.5 um) of RCOPU and SCOPU leaves were stained, fixed and observed under a Zeiss laser microscope. RCOPU leaves were thicker due to larger secondary epidermal cells. However, the vascular bundles were smaller. Thin cross-sections (100 nm)
were observed with a transmission electron microscope. RCOPU had fewer but larger chloroplasts and larger and more numerous starch grains in the chloroplasts. Fewer but larger chloroplasts, and larger starch grains in RCOPU suggest an extensive photosynthetic complex that may require higher herbicide concentrations to reach a non-reversible injury level.
Impacts
(N/A)
Publications
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Progress 01/01/93 to 12/30/93
Outputs
Yellow nutsedge is a serious weed in carrots, celery and onions. Several experiments were conducted to improve nutsedge control. Linuron plus adjuvants was applied postemergence to 10 cm nutsedge in carrots, and again 3 weeks later. Linuron 0.56 and 1.12 kg/ha plus 0.5% nonionic surfactant (NIS) or organosilicone surfactant (OSS) gave good suppression of nutsedge. Linuron plus crop oil concentrate (COC) was slightly less effective in desiccating the nutsedge. Nutsedge in celery was treated with one postemergence application of prometryn (1.12 or 2.24 kg/ha) or linuron (1.12 kg) plus 1% COC or 0.25 or 0.5% OSS. All treatments gave good desiccation of nutsedge. None of the treatments had an adverse effect on carrot or celery yield. Onions were treated preemergence and twice postemergence. Pendimethalin did not suppress nutsedge. Pendimethalin 2.24 kg followed by two applications of metolachlor 2.24 or 4.48 kg gave good suppression. Three applications of metolachlor 2.24
or 4.48 kg gave very good nutsedge suppression. Acetachlor at 0.56 or 1.12 kg did not suppress nutsedge, but at 2.24 kg it gave moderate suppression. Two applications of bentazon 0.56 or 1.12 kg postemergence suppressed nutsedge but caused severe onion injury.
Impacts
(N/A)
Publications
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Progress 01/01/92 to 12/30/92
Outputs
Common purslane that appeared to be resistant to linuron was collected from a carrot field in Imlay City, MI in 1991. Carrot had been planted in the field almost continuously for the past 25 years and treated with 2.24 kg ha(superscript -1) or more linuron each year. Seeds from linuron-susceptible common purslane were collected from the MSU Muck Farm. A triazine resistance kit was adapted to test seedlings for linuron resistance. In the test process, 4 mm leaf discs are suspended in a mixture of water, a buffer, and the herbicide and then exposed to light. Resistant discs photosynthesize and float, and susceptible discs sink. Four leaf discs from 2 plants from each location were tested. All Imlay City discs floated immediately, indicating that they were highly resistant to linuron. None of the Muck Farm discs floated, indicating that they were susceptible to linuron. Seven-week-old plants were treated on a bench sprayer with linuron at 1.12, 5.6, 11.2, 16.8, or 22.4
kg.ha(superscript -1). Twelve days after treatment (DAT), the visual vigor rating of Imlay City plants was 27% less than untreated controls. Muck Farm plants had an average 82% reduction in vigor. By 34 DAT, Imlay City plants had recovered and vigor was not statistically different from the controls. All treated Muck Farm plants were dead.
Impacts
(N/A)
Publications
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Progress 01/01/91 to 12/30/91
Outputs
Small grain cover crops help hold soil and may provide some weed suppression in cucumbers. To determine the most effective combination of cover crop and herbicides, rye and wheat were planted 24 Oct 90. Rye was planted 18 Apr 91. They were stunted with sethoxydim 0.11 kg/ha on 10 May 91 and killed with glyphosate 1.12 kg/ha on 12 Jun 91. Cucumbers were planted through the cover crops on 13 Jun 91. Barley was planted in separate plots along with cucumbers and allowed to grow as a companion crop. Barley was killed 2, 3 or 4 weeks after seeding. Naptalam 4.5 kg/ha and ethalfluralin 1.3 kg/ha were applied over some cover crop treatments. None of the cover crops alone gave sufficient season-long weed control. Naptalam plus ethalfluralin over the cover crops gave maximum crop yield and good weed control. Barley left in the crop longer than 2 weeks reduced cucumber yield.
Impacts
(N/A)
Publications
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Progress 01/01/90 to 12/30/90
Outputs
Carrots were sprayed in the field with postemergence herbicides and various surfactants to improve weed control, reduce herbicide rate, and reduce crop phytotoxicity. Linuron was applied to 0.28, 0.56 and 1.12 kg/ha and metribuzin was applied at 0.14 or 0.28 kg/ha in 187 liter/ha water. They were applied alone or in combination with crop oil concentrate 1%, nonionic surfactant 0.6%, organosilicone surfactant 0.1%, or nonionic surfactant/acidifier 0.6%. Linuron did not injure carrots at any of the rates tested. Linuron 0.28 kg plus surfactants controlled broadleaf weeds as well as linuron 1.12 kg, with the exception of ladysthumb (Polygonum persicaria). Metribuzin 0.14 kg plus surfactants controlled broadleaf weeds as well as metribuzin 0.28 kg alone. There were slight differences between the surfactants in level of control of ladysthumb.
Impacts
(N/A)
Publications
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Progress 01/01/89 to 12/30/89
Outputs
In greenhouse experiments mature broccoli plants were treated with foliar applications of 1500 ppm sodium molybdate plus several additives, including crop oil concentrate, a 6M linear alcohol surfactant, a 4.5M ethoxylated alkyl phenol surfactant, a 10M ethoxylated alkyl phenol surfactant, an alkyl aryl polyethylene glycol surfactant, and an organosilicone surfactant. The organosilicone surfactant gave the consistently highest uptake of Mo into plant leaves after 2 days of exposure. Crop oil concentrate also consistently increased Mo uptake. The other additives gave inconsistent results.
Impacts
(N/A)
Publications
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Progress 01/01/88 to 12/30/88
Outputs
In field experiments broccoli was exposed to several treatments, including: 4.1 kg bold center dot ha molybdenum as sodium molybdate preplant incorporated (ppi); and 0.15, 0.30, or 0.40 kg bold center dot ha molybdenum as sodium molybdate in 5 or 6 weekly foliar sprays from transplanting to harvest. Foliar treatments of 0.3 and 0.4 kg bold center dot ha molybdenum had highest levels of molybdenum in leaves at harvest. The 4.1 kg bold center dot ha ppi treatments had greatest yields.
Impacts
(N/A)
Publications
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Progress 01/01/87 to 12/30/87
Outputs
Cauliflower growing in the field was treated with calcium chloride (300 or 900 lb Ca per acre preplant or 300 lb sidedressed), calcium sulfate (300 or 900 lb Ca per acre preplant or 300 lb sidedressed) or calcium chloride sprays (10 lb Ca per acre 3 times). High levels of calcium fertilizer added to the soil reduced tipburn in mature cauliflower plants and caused increased levels of calcium in cauliflower leaves. Foliar applications were also somewhat effective in reducing tipburn. Calcium chloride appeared to be a better source of calcium than calcium sulfate for cauliflower.
Impacts
(N/A)
Publications
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Progress 01/01/86 to 12/30/86
Outputs
Cauliflower was grown in sand culture in the greenhouse with 3 levels of calcium: 40, 160, and 320 ppm in the nutrient solution. The plants were visually rated for tipburn and curd browning. Plant parts were weighed at harvest. Leaves were analyzed for calcium content with an atomic adsorption spectrophotometer. At the higher calcium levels there was virtually no tipburn or curd browning, while there was considerable tipburn and curd browning at the lowest level. Curd and total plant weights were higher from the two higher calcium treatments than from the low calcium treatments. The amount of calcium in leaves increased with the increase in calcium in the nutrient solution.
Impacts
(N/A)
Publications
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Progress 01/01/85 to 12/30/85
Outputs
Cauliflower was grown in nutrient solution in the greenhouse. Molybdenum was added to the nutrient solution at 0, 0.01, 0.1, 1.0, and 10 ppm. Plant parts were analyzed on an atomic absorption spectrophotometer for molybdenum content. The amount of molybdenum in plant parts increased as the amount in the nutrient solution increased. Cauliflower was grown in the field with 3 levels of calcium, 4 levels of molybdenum, and 2 levels of irrigation. Increased calcium resulted in reduced incidence of tipburn.
Impacts
(N/A)
Publications
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Progress 01/01/84 to 12/30/84
Outputs
Broccoli was treated with several levels of boron and molybdenum in field trials. Marketable yields of broccoli increased with soil applications of 6 kg/ha ammonium molybdate before planting followed by biweekly foliar applications of 0.23 kg/ha. Application of boron had no significant effect on yield. Broccoli was grown at several plant populations and treated with different fungicide treatments. Plants at the widest spacing (24,000 plants/ha) had the greatest downy mildew infection and lowest yield. Plants at the closet spacing (107,000 plants/ha) had moderate infection levels and highest yields. A systemic fungicide gave better disease control than a contact fungicide. Postemergence herbicides (oxyfluorfen and fluazifop) were applied to onions with rotary, air-assisted, and flat fan nozzles at several carrier rates to determine improved application methods. All carrier rates and nozzles at several carrier rates to determine improved application methods. All
carrier rates and nozzles gave similar control of weeds. Half rates of oxyfluorfen gave good control of easy-to-kill broadleaves, but were not sufficient on tough broadleaves. Applications at low carrier rates (47 1/ha) did not improve control.
Impacts
(N/A)
Publications
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Progress 01/01/83 to 12/30/83
Outputs
Herbicides were evaluated for weed control in onions, celery, carrots, broccoli,and rutabaga. Oxyfluorfen was found to be safe on onions and effective on weeds at rates of 0.07-0.14 kg/ha in repeated applications. Metolachlor gave good weed control in broccoli and rutabaga at 2.24 kg/ha. Diethatyl-ethyl gave good selectivity and weed control at 2.24 kg/ha in carrots and celery. These data are used to support registrations of these herbicides for use on vegetable crops. Cauliflower was observed for response to several molybdenum treatments. No deficiency symptoms appeared when cauliflower was sprayed weekly from transplanting to harvest with 0.21 kg/ha sodium molybdate. Some deficiency symptoms appeared when treatments were discontinued 4 weeks before harvest. No boron deficiency symptoms occurred in cauliflower when 5.6 kg/ha actual boron was broadcast preplant followed by foliar applications of 0.3 kg/ha boron 2 and 6 weeks after transplanting.
Impacts
(N/A)
Publications
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Progress 01/01/82 to 12/30/82
Outputs
Celery seed of two varieties and two seed lots were pregerminated at 10 degrees C and 24 degrees C and compared to non-pregerminated seeds for uniformity of germination, speed of germination, and spread of germination. The resulting plants were compared for size and weight before transplanting into the field and at mature harvest. There was a difference in uniformity of germination between seed lots of the same variety. There was no improvement in uniformity between plants from pregerminated and non-pregerminated seeds at transplanting or at harvest. Pregermination of celery seed at 10 degrees C reduced time in the greenhouse for transplant production by about 2 weeks, but did not appear to improve uniformity.
Impacts
(N/A)
Publications
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Progress 01/01/81 to 12/30/81
Outputs
Studies using mycorrhizae to enhance phosphorus uptake in onions were continued. The addition of mycorrhizae spores to muck soil at time of seeding increased onion yields in low-P areas. It appears that the main effect of the mycorrhizae is in protecting against drought stress, and the reduction in P uptake caused by drought. Onion and celery seed was primed and pregerminated to develop an effective means of obtaining uniform emergence in the field. Onions primed in salt solutions germinated faster, but concentration of germination was not improved. Celery seed pregerminated at 10mC emerged uniformly. Time to emergence was reduced from about 16 days for raw seed to 7 days for pregerminated seed. Total germination was improved slightly. Germination at 24mC resulted in less uniform but more rapid emergence. Tomato and pepper plants were grown in various size root cells to determine the relationship between cell size and shoot development, early yields, and total
yields. Larger cell sizes resulted in earlier yields, but there was no difference in total yields. Root cell size appears to have more effect on shoot size and yield than shoot growing space.
Impacts
(N/A)
Publications
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Progress 01/01/80 to 12/30/80
Outputs
Factors affecting establishment of asparagus continue to be studied. Depth of planting of asparagus crowns appears to affect longevity of the asparagus plants, with a 20 cm depth appearing to be optimum for survival. Deeper and shallower planted crowns did not survive as well 2 years after planting. Crowns planted at 20 cm produced the highest number of marketable spears. Onions were grown in fields with medium and very low soil phosphorous levels (95 and 3.3 kg/ha). Phosphorous was added at rates of 0, 30, 99, 197 kg/ha. Mycorrhizae spores were added to half the plots. High levels of phosphorous reduced mycorrhizae infection rate. Onions with very low phosphorous levels but sufficient mycorrhizae infection yielded similarly to onions with high phosphorous and low mycorrhizae levels. Addition of mycorrhizae spores increased infection levels at all phosphorous levels. Tomato transplants grown in the greenhouse in Michigan in different size soil blocks and of
different ages were compared to similar plants grown in Florida. The plants were transplanted into the field in southwestern Michigan. Younger, larger plants produced earlier yields, but all plants produced similar total yields. Evidently age is as critical as plant size in ability to withstand transplant shock, with younger plants being the most vigorous.
Impacts
(N/A)
Publications
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Progress 01/01/79 to 12/30/79
Outputs
Factors effecting establishment of asparagus continue to be studied. Depth of planting of asparagus crowns appears to effect longevity of the asparagus plants, with an 8-inch depth appearing to be optimum for survival. Deeper and shallower planted crowns did not survive as well 1 year after planting. Onions were grown with different levels of P, fumigation, and mycorrhizae spores added. Fumigation reduced mycorrhizae levels in muck soil, but did not destroy the native population. Mycorrhizae spore levels in fumigation and non-fumigated muck soil were raised by adding inoculum at time of planting onion seed. Higher P levels resulted in lower mycorrhizae spore levels in the soils. Warm season crops were grown under a variety of conditions to speed growth including mulches, tents, and covers. However, melons and peppers responded very poorly, and tomatoes only slightly better. The problem appears to be low soil temperatures as a result of a cloudy, damp, cool Spring
in 1979. Unless soil temperature can be raised and maintained above 13C, these warm weather crops will not benefit much from the use of mulches and covers.
Impacts
(N/A)
Publications
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