Progress 07/01/03 to 09/30/08
Outputs
OUTPUTS: All experimental data has been analyzed and most of it published in scientific papers and grower publications. A graduate student and a postdoctoral researcher were trained and went on to faculty positions at land grant universities. Collaboration with University of California farm advisers and the principal investigator led to a comprehensive publication on organic vegetable management which will be published through the University of California. Over 50 talks to growers, professional organizations delivered information and training related to the sustainable crop and pest management systems developed in the project. We made extensive use of the Division of Agriculture and Natural Resources work groups and statewide programs to inform advisers and others of our progress. PARTICIPANTS: Milt McGiffen, Project Director. Supervised personnel, wrote grants, analyzed and published data, trained students, postdoctoral researchers, and others. Extension of results through county extension programs and professional organizations. Guangyao (Sam) Wang -- conducted research and analyzed data as part of his PhD thesis and postdoctoral fellowship. Currently a Cropping Systems Specialist for the University of Arizona. Edmund Ogbuchiekwe -- Staff research associate responsible for daily project operations. Received regular training in pesticide application, data analysis and presentation, and the biological mechanisms of the project. Training led to his current career as community college instructor. University of California Farm Advisors: Eric Natwick, Jose Aguiar, Rick Bottoms, Khalid Bali, Aziz Baameur, Richard Smith, Laura Torte, Mark Gaskel, Benny Fouche. Provided technical expertise, helped write and disseminate information. Pesticide Applicators Professional Association: organized workshop to train applicators. Project results were frequently disseminated through these workshops. University of California faculty: Michal Stanghellini, Ole Becker, Antoon Ploeg, Greg Walker, Nick Toscano, Tim Hartz, Giles Waines, David Crowley, James Borneman -- technical expertise and co-authors on publications. Dr. Naresh Pradhan Agricultural Economics, U of HI; Greg Balmer, UCR Entomology. Graduate Students Trained (all PhD in Botany): Guangyao Wang, 2005; Oli Bachi, 2011; Abira Selvaraj, 2012; Institutional Units Involved: South Coast Research and Extension Center, Citrus Research Center, Coachella Valley Agricultural Research Station. UC Workgroups: Desert. Continuing Conferences: Vegetable Crops and Pest Management. Cooperation: USDA Salinity Laboratory has been generous in providing expertise and equipment. Soil Conservation Service has also provided expertise and participated in information delivery. TARGET AUDIENCES: Target audiences include growers, agri-industry, and related non-profit and governmental agencies. We routinely work with county extension offices and professional organizations to assess needs. The University of California has statewide programs dedicated to pest management, small farms, and sustainable agriculture. We work with members of those programs to reach their audiences as well as train the members of the program. We made several reports through work group meetings as part of this process. California is very ethnically diverse, with many different Native American, Hispanic, and Asian communities. We work with grower groups and University of California colleagues and statewide programs to reach these groups. I give about a dozen talks per year, most of them related to the themes in the project. I especially target PAPA and CAPCA, professional organizations for pest control advisors and pesticide applicators, as more and more of their responsibilities involve organic agriculture and cover crops. I am Chair of the Desert Workgroup and active in many other UC ANR workgroups, and use these as forums for information dissemination. We have given several day long courses on organic production aimed principally at growers. A University of CA published manual has been developed based upon those presentations and should be available for wide distribution by the end of the year. PROJECT MODIFICATIONS: The project covered a broad range of crop and pest management issues. It evolved over time and created new statistical methods, simulation models, a few new cover crop varieties. All of those are very significant but still fit within the original goals of the project.
Impacts
The project was successful in changing the way farmers and others looked at cover crops, compost and other high carbon soil amendments. We were able to show many positive changes that result when organic amendments are used in the low organic matter soils common in California and in deserts in general. This is timely in light of recent interest in carbon storage. The student and postdoctoral researcher trained on the project continue to collaborate with Dr. McGiffen and have developed their own novel research related to organic amendments and organic agriculture. We have seen greater acceptance by the larger community for methods using organic amendments and cover crops, and have responded to many requests by students and homeowners for information on their use on home sites and in school projects. This knowledge has led to follow up in our current research by securing a multi-state grant to work on the effect of cover crops on pest management, research to determine how compost teas work, and the ongoing training of two PhD candidates.
Publications
- 1) Wang G., M.E. McGiffen, E.J. Ogbuchiekwe, and L. Butler. 2009. Economic return of purple and yellow nutsedge management in vegetable production of southern California. Crop Protection. 28,319-326. 2) Wang G., M. Ngouajio, M.E. McGiffen, and C.M. Hutchinson. 2008. Summer cover crop and in-season management system affect nitrogen availability and weed density in lettuce and cantaloupe. Agronomy Journal. 100, 1587-1593. 3) Wang G., M. Ngouajio, M.E. McGiffen, and C.M. Hutchinson. 2008. Summer cover crop and in-season management system affect growth and yield of lettuce and cantaloupe. HortScience 43:1398-1403 4) Wang G., M. Ngouajio, and D.D. Warncke. 2008. Nutrient cycling, weed suppression, and onion yield following brassica and sorghum sudangrass cover crops. HortTechnology. 18, 68-74. 5) Wang G., M.E. McGiffen, and E.Ogbuchiekwe. 2008. Alternative management of purple nutsedge (Cyperus rotundus) and yellow nutsedge (C. esculentus). Weed Res. 48, 420-428.
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: A multiyear study on the effect of summer cover crop and management system on nitrogen availability, weed growth, and yield in fall romaine lettuce (Lactuca sativa L.) and spring cantaloupe (Cucumis melo L.) was completed, analyzed, published, and disseminate in several formats. Cover crop treatments included cowpea [Vigna unguiculata (L.) Walp.] incorporated into the soil in the fall (CPI), cowpea used as mulch in the fall (CPM), sudangrass [Sorghum bicolor (L.) Moench] incorporated into the soil in the fall (SGI), and a bare ground control (BG). The management system treatments included conventional (CON), integrated crop management (ICM), and organic (ORG). CPM and SGI increased soil organic matter content and changed the soil nitrogen profile during both lettuce and cantaloupe growth periods. Soil organic matter was higher in the ORG system compared to the ICM and CON systems, but less soil N was present during the lettuce growth period. Nitrate leaching was reduced
under ORG management during lettuce and cantaloupe growth periods. The CPM treatment had lower weed growth during the lettuce growth period, but higher weed biomass during the cantaloupe growth period in the first growing season compared to other cover crop treatments. Weed growth was not affected by management system during lettuce growth. During the cantaloupe season, weed growth in the ORG treatment was lower or equivalent in the first three years but higher in the fourth year compared to the CON and ICM systems. Plants in the CPI treatment had the highest lettuce yield in the first two growing seasons, while the SGI treatment had the lowest yield in the first growing season. However, SGI and CPI treatments increased cantaloupe yield compared to the CPM and BG treatments. The ORG treatment had lower or equivalent lettuce yield in the first growing seasons and higher or equivalent yield in the last two growing seasons compared to CON and ICM systems. Cantaloupe yields were reduced
in the ORG management system by 15% and 18% compared to the CON and ICM system, respectively. Results were disseminated in 14 talks given to pest control advisors and other industry personnel, newspaper and trade publication interviews, and in an upcoming manual on organic vegetable production.
PARTICIPANTS: Cooperators: Antoon Ploeg, UCR Nematology; Cerruti Hooks, U of HI Entomology. Jose Aguiar, UCCE Riverside Co.; Dr. Naresh Pradhan Agricultural Economics, U of HI; Greg Balmer, UCR Entomology. Graduate Students Trained (all PhD in Botany): Guangyao Wang, 2005; Oli Bachi, 2011; Abira Selvaraj, 2012; Institutional Units Involved: South Coast Research and Extension Center, Citrus Research Center, Coachella Valley Agricultural Research Station. UC Workgroups: Desert. Continuing Conferences: Vegetable Crops and Pest Management. Cooperation: USDA Salinity Laboratory has been generous in providing expertise and equipment. Soil Conservation Service has also provided expertise and participated in information delivery.
TARGET AUDIENCES: I give about a dozen talks per year, most of them related to the themes in the project. I especially target PAPA and CAPCA, professional organizations for pest control advisors and pesticide applicators, as more and more of their responsibilities involve organic agriculture and cover crops. I am Chair of the Desert Workgroup and active in many other UC ANR workgroups, and use these as forums for information dissemination. We have given several day long courses on organic production aimed principally at growers. A University of CA published manual has been developed based upon those presentations and should be available for wide distribution by the end of the year.
Impacts
Organic production is an increasing segment of the market. Science-based knowledge in this area is limited, something that is frequently and vigorously pointed out by clientele. This research provides cost studies that compare the economic return of vegetable production systems with or without summer cover crops. Yield and net return were greatest when cantaloupe and lettuce were planted after the incorporation of a cowpea cover crop. Profits depended upon whether lettuce and cantaloupe were grown organically, and the price paid growers for their crops. Clientele find the cost studies to be particularly useful in making sound business decisions that sustain their farming operations, and for use in obtaining loans for future farming projects. The new pest resistant cover crop varieties developed by our current research should increase profitability by decreasing reliance on synthetic pesticides and fertilizers. Adoption of these methods has been steadily increasing
among both conventional and organic growers. A new statistical method for determining order of population means was developed that will help breeders better sort genotypes in terms of desired characteristics.
Publications
- Wang G., J.D. Ehlers, E.C.S. Marchi, and M.E. McGiffen. 2006. Competitive ability of cowpea (Vigna unguiculata) genotypes with different growth habit. Weed Sci. 54, 775-782.
- Wang G., M.E. McGiffen, J.L. Lindquist, J.D. Ehlers, and I. Sartorato. 2007. INTERCOM simulation of competition between three cowpea (Vigna unguiculata) genotypes and sunflower (Helianthus annuus) or purslane (Portulaca oleracea). Weed Res. 47, 129-139.
- Wang G., M.E. McGiffen, and J.D. Ehlers. 2006. Replacement series of six cowpea (Vigna unguiculata) genotypes with sunflower (Helianthus annuus) or purslane (Portulaca oleracea). Weed Sci. 54, 954-960.
- Wang G., M. Ngouajio, M.E. McGiffen, and C.M. Hutchinson. 2008. Summer cover crop and in-season management system affect nitrogen availability and weed density in lettuce and cantaloupe. Agronomy Journal. Submitted in in Jan. 2008.
- Wang G., M. Ngouajio, M.E. McGiffen, and C.M. Hutchinson. 2008. Summer cover crop and in-season management system affect growth and yield of lettuce and cantaloupe. HortSci. Submitted in in Jan. 2008.
- Jeske D., G. Wang, and M.E. McGiffen. 2007. Testing a partial ordering of population means with application to inference about growth habits of cowpea genotypes. Biometrics. 63:1278-1282.
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Progress 01/01/06 to 12/31/06
Outputs
Varietal growth habit could play a key role in the competitiveness of crop plants with weeds. The relative competitiveness of two erect, two semi-erect and two prostrate cowpea genotypes with a tall growing species (common sunflower) or a low-growing species (common puslane) was evaluated in 12 replacement series experiments conducted in 2003 and 2004. Growth analysis of the six cowpea genotypes and two weed species were also conducted to investigate the relationship of competitiveness and growth. Cowpea genotype and competitor biomass were used to calculate relative yield total (RYT) and aggressivity indices (AI). RYT and AI means of six cowpea genotypes were compared using ANOVA, and an isotonic regression were used to confirm the relative competitive superiority of the cowpea growth types. All cowpea genotypes had similar RYTs when grown with sunflower or purslane, indicating that cowpea used the same resources as sunflower or purslane. When grown with sunflower,
erect genotypes and semi-erect genotypes had higher AI than prostrate genotypes. When grown with purslane, erect and prostrate genotypes had higher AI than semi-erect genotypes. The results were confirmed by isotonic regression tests on the respective AI order. Correlation and regression between AI and growth parameters showed that relative growth rate (RGR), leaf area ratio (LAR), and height growth rate (HGR) explained 92% variation of AI when cowpeas were grown with sunflower, and that leaf weight ratio (LWR) and biomass explained 82% of the variation of AI when cowpeas were grown with purslane. These experiments indicate that cowpea genotypes differ in their ability to compete with purslane or sunflower. Erect genotypes were the most competitive, suggesting that an erect growth habit may be more effective in suppressing weeds than semi-erect or prostrate growth habits. These results are consistent with field experiments on the competitiveness of erect, semi-erect and prostrate
cowpea genotypes. A new project to determine the affect on pest management when cover crops are included in vegetable crop rotations was initiated. The research includes collaborators from all the pest management disciplines from the states of CA, FL, and HI.
Impacts
Cover crop use is growing and currently exceeds several thousand acres. The improved genotypes should increase the acreage of use, and encourage new that include using cover crops instead of pesticides. The increased demand for cover crops must be met with increased seed production. Cowpea cover crop seed was previously produced in the Southeast, and the shipping charges increased grower costs. The new genotypes created by this project will allow the production of cowpea cover crop seed in the low desert. This creates a new industry for limited-resource growers that benefit many segments of the on-farm and larger community. We have completed cost studies that compare the economic return of vegetable production systems with or without summer cover crops. Yield and net return were greatest when cantaloupe and lettuce were planted after the incorporation of a cowpea cover crop. Profits depended upon whether lettuce and cantaloupe were grown organically, and the price
paid growers for their crops. The new pest resistant cover crop varieties developed by our current research should increase profitability by decreasing reliance on synthetic pesticides and fertilizers. A new publication on on Organic Vegetable Production is in the final stages of review for publication by the University of California's Division of Agriculture and Natural Rsources.
Publications
- McGiffen, M.E., Jr., W.T. Lanini, E.J. Ogbuchiekwe. Final Report: The Tolerance of Widely Used Melon Varieties to New and Potential Melon Herbicides. California Melon Research Board, 2005 Annual Reports, pp. 31-48, January 7, 2006.
- McGiffen, M.E., Jr. P.A. Roberts, and J. Ehlers. Development and dissemination of a cowpea cultivar for cover crops. WSARE, USDA/CSREES Sustainable Agriculture Research and Education program, Project Number SW02-034, Cooperative Agreement Number 2002-38640-11763. 20 pages, June 22, 2006.
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Progress 01/01/05 to 12/31/05
Outputs
Competitive cover crop varieties are needed to reduce weed problems and herbicide use. Identifying specific crop traits related to competitive ability would provide breeders with useful information that could be used to develop an ideotype for highly competitive cover crop varieties. Cowpea varieties with different growth habits were grown with sunflower or purslane to determinate which growth habit (erect, semi-erect, and prostrate) is more competitive to weeds. Regression models were used to analyze additive and replacement series experiments. New statistical methods were developed for ranking relative competitiveness of prospective new varieties. The results showed that erect varieties were more competitive to weed than semi-erect varieties and prostrate varieties. An ecophysiological model, INTERCOM, is used to understand competitive mechanisms. The validated INTERCOM model reaffirmed the importance of growth habit over physiological factors such as photosynthetic
rate.
Impacts
Cowpea cover crop use is growing and currently exceeds several thousand acres. The improved genotypes should increase the acreage of use, and encourage new that include using cover crops instead of pesticides. The increased demand for cover crops must be met with increased seed production. Cowpea cover crop seed was previously produced in the Southeast, and the shipping charges increased grower costs. The new genotypes created by this project will allow the production of cowpea cover crop seed in the low desert. This creates a new industry for limited-resource growers that benefit many segments of the on-farm and larger community. We have completed cost studies that compare the economic return of vegetable production systems with or without summer cover crops. Yield and net return were greatest when cantaloupe and lettuce were planted after the incorporation of a cowpea cover crop. Profits depended upon whether lettuce and cantaloupe were grown organically, and the
price paid growers for their crops. The new pest resistant cover crop varieties developed by our current research should increase profitability by decreasing reliance on synthetic pesticides and fertilizers. We are currently developing a series of course and a training manual on Organic Vegetable Production that will disseminate results from this project. Our first training session in Salinas had over 100 attendees. We continue to give grower talks and notify grower groups of our progress.
Publications
- No publications reported this period
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Progress 01/01/04 to 12/31/04
Outputs
Competitive cover crop varieties are needed to reduce weed problems and herbicide use. Identifying specific crop traits related to competitive ability would provide breeders with useful information that could be used to develop an ideotype for highly competitive cover crop varieties. Cowpea varieties with different growth habits were grown with sunflower or purslane to determinate which growth habit (erect, semi-erect, and prostrate) is more competitive to weeds. Regression models were used to analyze additive and replacement series experiments. The results showed that erect varieties were more competitive to weed than semi-erect varieties and prostrate varieties. However, the simple regression models do not provide much information with competitive mechanisms which are helpful to breed new cowpea varieties. An ecophysiological model, INTERCOM, is used to understand competitive mechanisms. Validated INTERCOM model will provide us with more information about
competitive cover crop traits, including competitive growth habit. Cowpea cover crop use is growing and currently exceeds several thousand acres. The improved genotypes should increase the acreage of use, and encourage new that include using cover crops instead of pesticides. The increased demand for cover crops must be met with increased seed production. Cowpea cover crop seed was previously produced in the Southeast, and the shipping charges increased grower costs. The new genotypes created by this project will allow the production of cowpea cover crop seed in the low desert. This creates a new industry for limited-resource growers that benefit many segments of the on-farm and larger community. We have completed cost studies that compare the economic return of vegetable production systems with or without summer cover crops (Ogbuchiekwe et al. 2004). Yield and net return were greatest when cantaloupe and lettuce were planted after the incorporation of a cowpea cover crop. Profits
depended upon whether lettuce and cantaloupe were grown organically, and the price paid growers for their crops. The new pest resistant cover crop varieties developed by our current research should increase profitability by decreasing reliance on synthetic pesticides and fertilizers. We are currently developing a series of course and a training manual on Organic Vegetable Production that will disseminate results from this project. Our first training session in Salinas had over 100 attendees. We continue to give grower talks and notify grower groups of our progress.
Impacts
This is the first time a crop was selected for ability to resist weeds. New methods of vegetable production that use less pesticides and potentially lower costs were developed and compared economically. Much of the research was conducted under certified organic rules, but the results can be used by conventional growers as well. New cropping systems that use cover crops and reduced tillage, novel cover crop varieties that outcompete weeds, and low rate herbicides are options that most growers can readily integrate into their operations. The information is in a form that growers and others can use to objectively evaluate the utility of these methods for their specific situation, including spread sheets of cost of production studies.
Publications
- Ogbuchiekwe, E. J., M. E. McGiffen, Jr., J. Nunez, and S. A. Fennimore. 2004. Tolerance of carrot (Daucus carota L.) to low-rate preemergent and postemergent herbicides. HortSci. 39:291-296
- Ogbuchiekwe, E.J., M.E. McGiffen, Jr., and M. Ngouajio. 2004. Economic return in production of cantaloupe and lettuce is affected by cropping system and management practice. HortScience 39:1321-1325.
- Huang, X., M. McGiffen, and I. Kaloshian. 2004. Reproduction of Mi-virulent Meloidogyne incognita isolates on Lycopersicon spp. J. Nematol. 36:69-75
- Wang, G., J.D. Ehlers, E.J. Ogbuchiekwe, E.J., S. Yang, and M.E. McGiffen, Jr. 2004. Competitiveness of erect, semierect, and prostrate cowpea genotypes with sunflower (Helianthus annus) and purslane (Portulaca oleracea). Weed Science 52:815-820.
- Ngouajio, M. and M.E. McGiffen, Jr. 2004. Sustainable vegetable production: effects of cropping systems on weed and insect population dynamics. Acta Hort. 638:77-83
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Progress 01/01/03 to 12/31/03
Outputs
An economic analysis of the affect of cropping system, crop management practice and pricing mechanism on the net return or rate of return in vegetable production was conducted on two years of field data. Incorporating a cowpea cover crop into the soil improved the return for both lettuce and cantaloupe in both 1999 and 2000, while results with sudangrass varied with year. The integrated crop management system showed the highest return while the returns in the organic system showed some losses in one year and regained in the second year, but with higher return in favorable pricing. However, rate of return for every dollar invested in lettuce and cantaloupe productions favored cowpea crop incorporated rotation over other cover crops. The integrated crop management system was also favored over organic and conventional management practices. The growth habits of the crop and competing weed species are important determinants of crop-weed competition. Three cowpea (Vigna
unguiculata (L.) Walp.) genotypes with similar vegetative vigor but different growth habit were assessed for their relative competitiveness with two weed species. Iron-Clay (IC) grows erect, IT89KD-288 (288) semi-erect, and UCR 779 (779) prostrate. Common purslane (Portulaca oleracea L.), a short statured weed, and common sunflower (Helianthus annuus L.), a tall species, were planted within the cowpea rows. Cowpea canopy height and width, leaf area, dry weight, and light intensity above and below sunflower and cowpea canopies were measured weekly from 21 days after planting. Sunflower reduced the leaf area, amount of light received, and biomass of all cowpea genotypes. Purslane reduced the leaf area of 779 and the biomass of 288 and 779, but the biomass and leaf area of IC was not affected. The experiments indicate that cowpea genotypes differ in their ability to compete with purslane and sunflower. IC was the most competitive genotype, suggesting that an erect growth habit may be
more effective in suppressing weeds than semi-erect or prostrate growth habits. Sixteen herbicide treatments were applied both as preemergence (PRE) and postemergence (POST) applications to carrot. Carrot was generally more tolerant to PRE herbicide applications than to POST applications. Carrot was tolerant to PRE and POST imazamox and triflusulfuron at both locations. Treatments that injured carrot tops early in the growing season did not always reduce yield at the end of the season. Carrots grown in the Imperial Valley and in the San Joaquin Valley were tolerant to carfentrazone, sulfentrazone, and imazamox. PRE application of herbicides increased forked roots more than POST. Twelve sweet corn cultivars were evaluated in 1999 and 2000 for their tolerance to premergence, postemergence and combined preemergence and postemergence applications of halosulfuron at different rates. All cultivars were generally tolerant to halosulfuron regardless of rates and timing, but some cultivars
sustained slight injury that affected the height of stalk, length and diameter of ear but did not reduce yield.
Impacts
New methods of vegetable production that use less pesticides and potentially lower costs were developed and compared economically. Much of the research was conducted under certified organic rules, but the results can be used by conventional growers as well. New cropping systems that use cover crops and reduced tillage, novel cover crop varieties that outcompete weeds, and low rate herbicides are options that most growers can readily integrate into their operations. The information is in a form that growers and others can use to objectively evaluate the utility of these methods for their specific situation, including spread sheets of cost of production studies.
Publications
- Hutchinson, C.M., M.E. McGiffen Jr., J.J. Sims, and J.O. Becker. 2003. Fumigant combinations for Cyperus esculentum L control. Pest Management Science 60:369-374.
- Ngouajio, M., M.E. McGiffen, Jr., and C.M. Hutchinson. 2003. Effect of cover crop and management system on weed populations in lettuce. Crop Protection 22(1):57-64
- Ogbuchiekwe, E.J., M.E. McGiffen, Jr., J. Nunez, and S.A. Fennimore. 2003. Tolerance of carrot (Daucus carota L.) to low-rate preemergent and postemergent herbicides. HortSci. IN PRESS
- Wilen, C.A., M.E. McGiffen, Jr., and C.L. Elmore. 2003. Nutsedge. Pest Notes Number 7432, University of California Statewide Integrated Pest Management Program, Davis, CA.
- McGiffen, Jr., M.E. 2003. Alternatives for Purple and Yellow Nutsedge Management. 2003 Proceedings of the California Weed Science Society 55: 150-151.
- Wang, G., J. Ehlers, E. Ogbuchiekwe, and M.E. McGiffen, Jr. 2003. Competition Between Cowpea Cover Crop Varieties and Weeds. 2003 Proceedings of the California Weed Science Society 55: 150-151.
- Ogbuchiekwe, E.J., M. Ngouajio, and McGiffen, M.E. 2003. Economic return for lettuce and cantaloupe is affected by cropping system and management practice. Weed Science Society of America Abstracts 43:9.
- Wang, G., Ehlers, J., Ogbuchiekwe, E.J., and McGiffen, M.E. 2003. Economic return for lettuce and cantaloupe is affected by cropping system and management practice. Weed Science Society of America Abstracts 43:9.
- Wang, G., J. Ehlers, E. Ogbuchiekwe, and M.E. McGiffen, Jr. 2003. Cowpea varietal resistance to weeds. 4th National Integrated Pest Management Symposium p. 85.
- Wang, G., J. Ehlers, E.J. Ogbuchiekwe, and M.E. McGiffen, Jr. 2003. Competition between cowpea cover crop varieties and weeds. Weed Science Society of America Abstracts 43:8.
- McGiffen, M.E. Jr. Grower Directed Research and Outreach on Integrated Weed Management for Intensive Vegetable Production, Progress Report, USDA-CSREES, 5 pages, February 2003.
- McGiffen, M.E., Jr., P. Roberts, J. Ehlers, and W. Mathews. The Development and Dissemination of a Cowpea Cultivar for Cover Crops. Western Sustainable Agriculture Research and Education, USDA-ARS. January 11, 2003. 2 pages.
- McGiffen, Jr., M.E., O. Becker, and A. Ploeg. Nematode and Weed Suppressive Cover Crops as Replacements for Methyl Bromide. Department of Pesticide Regulations, California Department of Food and Agriculture, 26 pages, May 16, 2003.
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Progress 01/01/02 to 12/31/02
Outputs
We have successfully developed cropping system options that can affect pest populations. The two most prominent accomplishments this year have resulted from collaboration with soil scientists and economists. Field experiments were established at the University of California Desert Station in Coachella Valley from 1998 to 2000. The main plot treatments included summer cowpea used as mulch in the fall, summer cowpea incorporated into soil in the fall, summer sudangrass incorporated into the soil in the fall, and summer fallow (bare-ground). An economic comparison of cover crop treatments and crop management programs vs. the effect on yield, crop value, value of hand weeding, costs of production and net-return, and dollar investment from each treatment was determined. Among the cropping systems tested in 1999, lettuce following the incorporation of a cowpea cover crop produced the highest yield 1082.43 boxes/ha, with a net return of $883.04/ha. The return for each dollar
invested in the cowpea-incorporated system was an additional $0.65 if cowpea incorporated was chosen over cowpea mulch. In 2000, the net-return from lettuce following cowpea incorporated was much higher with 1294.23 boxes/ha and a net-return of $1698.46/ha. In 1999, cantaloupe grown in the cowpea-incorporated system had the highest net-return of $973.34/ha with 874.58 boxes. An additional $0.93 was made for choosing cowpea incorporated over sudangrass. In 2000, cantaloupe grown in the cowpea-incorporated system had even higher yields than in 1999, producing 1522.89 boxes/ha and returning over $3000.00. And an additional $0.93 was made for choosing cowpea incorporated over sudangrass cover crop. Overall, the rate of return on investment favored cowpea incorporated over all cover crops. We also found differences in the soil microbiology of the cropping systems based upon the amount of organic material amended to the soil. It appears that organic amendments that increase soil microbial
populations that feed on weed seed, reducing the severity of weed infestations.
Impacts
The results of our cost/benefit study encouraged the adoption of alternative cropping systems by demonstrating profitability, and providing growers with spreadsheets and other tools to assess the profitability of these methods on their farms. Favorable changes in soil microbial populations indicate that recycling compost on agricultural fields can improve crop production. Both of these results are in the interests of both the farm and urban population, as urban dwellers see value in recycling of yard waste and other farm practices with reduced environmental impact.
Publications
- Hutchinson CM, McGiffen Jr ME, Sims JJ, & Becker JO, Fumigant combinations for Cyperus esculentum L. control. Pest Management Science. (2002) Received for review October 31, 2002..
- Ngouajio, M., M.E. McGiffen, Jr., and C.M. Hutchinson. 2003. Effect of cover crop and management system on weed populations in lettuce Crop Protection 22(1):57-64
- McGiffen, Jr., M.E., M. Ngouajio, D. Crowley, J. Borneman, C.M. Hutchinson. 2002. Soil organic amendments change low organic matter agroecosystems. International Horticultural Congress and Exhibition 26:289.
- Ngouajio, M. and M.E. McGiffen, Jr. 2002. Sustanable vegetable production: Effects of cropping systems on weed and insect population dynamics. International Horticultural Congress and Exhibition 26:279-280.
- McGiffen, M.E., Jr., I. Lebron, and M. Ngouajio. 2001. Organic and other alternative cultural systems for carrots. 2001 Annual Report, California Fresh Carrot Advisory Board, pp. 83-100.
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Progress 01/01/01 to 12/31/01
Outputs
Changes in the cropping system cause significant modifications of the agroecosystem, which in turn impact pest population dynamics and management. Field experiments were conducted to study the effect of summer cover crop and in-season management system on weed infestations in lettuce (Lactuca sativa L.). The experiment was a factorial with summer cover crop and management system as the two factors. Cover crops were cowpea [Vigna unguiculata (L.) Walp.] incorporated into the soil in the fall (CWPI), cowpea used as mulch in the fall (CWPM), sudangrass (Sorghum vulgare) incorporated into the soil in the fall (SDNG), and dry fallow (DFLW). Management systems were organic (ORG), integrated management (ICM), and conventional (CNV) systems. In general there was no interaction between cover crop and management system. Cowpea and sudangrass showed high populations of volunteer cover crops. Two weeks after crop transplanting in 1999, over 100 and 700 volunteer cover crop
seedlings m-2 emerged in CWPI and SDNG plots respectively. In 2000 however, early kill of cover crops eliminated the problem. Weed species richness was greatest early in the growing season and was affected by cover crop. Fewer species emerged in CWPM plots in general but perennial species became important with time. After two years DFLW showed greater weed populations than all cover crop treatments. Weed populations were similar in all management systems in 1999. However, in 2000, the ORG and ICM systems showed better weed suppression than the CVN system. CWPI significantly increased yield over the two years. SDNG showed potential toxicity to lettuce and DFLW yield declined the second year. Yield under the ORG system was low in 1999 and equivalent to that in the CVN and ICM systems in 2000. These results indicate that cowpea can improve both conventional and organic vegetable production systems.
Impacts
We have demonstrated significant, long-term changes that result from increasing the organic matter content of low organic matter soils. This should encourage farmers to recycle urban yardwaste. It will also directly help farmers reduce costs through decreased use of synthetic agrichemicals.
Publications
- Aguiar, J.L., W.A. Williams, W.L. Graves, M.E. McGiffen, Jr., J.V. Samons, J.D. Ehlers, and W.C. Matthews, Jr. 2001. Factor for estimating nitrogen content of cowpea as a cover crop. J. Agron. Crop Sci. 186:145 -149.
- Ngouajio, M., M.E. McGiffen, Jr., and K.J. Hembree. 2001. Tolerance of tomato (Lycopersicon esculentum) varieties to velvetleaf (Abutilon theophrasti) interference. Weed Sci. 49:91-98.
- Ngouajio, M., M.E. McGiffen, Jr., S. Mansfield, E.J. Ogbuchiekwe. 2001. Comparison of methods to estimate weed populations and their performance in yield loss description models. Weed Sci. 49:385-394.
- My View: The Food Quality Protection Act. (with 11 co-authors). 2000. Weed Sci. 48:1.
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Progress 01/02/00 to 12/31/00
Outputs
We have collaborated with the University of Arizona and many others to investigate organic and other alternative cropping systems at sites in the major vegetable production area of the lower Colorado River desert. This research evaluates the potential of summer cover crops and management systems (ICM, organic, and conventional) for intensive vegetable production in the desert. Two cover crops (cowpea and sudangrass) were compared to traditional summer fallow. Sudangrass was incorporated into the soil and cowpea was either incorporated or used as mulch (reduced tillage system). Cowpea mulch increased daily minimum soil temperature and decreased maximum soil temperatures, which may allow growers to extend their season into more profitable markets. The cowpea cover crop and the organic system also provided improved weed suppression. No increase in insect pest population was observed in the cover crop plots, indicating that they do not serve as an alternate host for
pests. Cowpea cover crop significantly increased yield of fall planted lettuce and winter/spring planted cantaloupe. With sudangrass, this beneficial effect was observed only on cantaloupe. Reduced lettuce yield following sudangrass was possibly due to nutrient immobilization or allelopathy from the cover crop residues. Our results strongly support the use of cowpea cover crops prior to fall planted lettuce in the desert. Additional investigations are needed on the benefits of sudangrass cover crop in a rotation where it precedes lettuce. A reduced tillage system using cowpea mulch reduced weed populations and provided nutrients to the fall crop. However, due to rapid residue decomposition in the desert, those benefits were not carried over to the spring cantaloupe crop.
Impacts
There has been a strong, consistent interest in reducing pesticide use over the last 40 years. Consumption of organic produce has increased exponentially over the last 10 years. Organic products are now common grocery items. Desert vegetable growers have become increasingly interested in sustainable production systems. Prior to the start of this project, there was little use of cover crops in desert valleys. Production of organic produce has increased greatly, with many large and small growers growing at least part of their acreage for certification. Organic produce has been identified as a niche market that can potentially sustain profitability for many farmers. Many conventional growers are adopting cover crops and other methods developed by this project. Growers and researchers are considering cover crops for many conventional agriculture applications. It is thought that by breeding new cover crop specific varieties with enhanced pest resistance we may create a
cultural alternative to methyl bromide and other pesticides.
Publications
- Ngouajio, M., M.E. McGiffen, Jr., and K.J. Hembree. 2001. Tolerance of tomato (Lycopersicon esculentum) varieties to velvetleaf (Abutilon theophrasti) interference. Weed Sci. 49:91-98
- Ngouajio, M., M.E. McGiffen, Jr., S. Mansfield, E.J. Ogbuchiekwe. 2001. Comparison of methods to estimate weed populations and their performance in yield loss description models. Accepted for publication in Weed Sci.
- My View: The Food Quality Protection Act. (with 11 co-authors). 2000. Weed Science 48:1.
- Bell, C.E., B.E. Boutwell, E.J. Ogbuchiekwe, and M.E. McGiffen. 2000. Weed control in carrots: The efficacy and economic value of linuron. HortSci. 35(6)1089-1091.
- Hutchinson, C.M. and M.E. McGiffen. 2000 Cowpea Cover Crop for Weed Control in Desert Bell Pepper Production. HortScience - Hutchinson, C.M. and M.E. McGiffen. 2000. Cowpea Cover Crop for Weed Control in Desert Bell Pepper Production. HortScience Vol. 35(2):p. 196-198
- McGiffen, M.E., Jr., J. Ehlers, J. Aguiar. 2000. Introduction. Colloquium on Organic Horticulture. HortTech. 10(4):661-662.
- McGiffen, M.E., (ed.).2000. Colloquium on Organic Horticulture. HortTech. 10(4):661-662.
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Progress 01/01/99 to 12/31/99
Outputs
A two-year field project was conducted in Thermal, CA investigating cowpea (Vigna unguiculata) mulch (CM) as an alternative weed control option in pepper (Capsicum annuum) production. Treatments included bare ground production system (BG) with hand weeding, BG with no weeding, a cowpea mulch production system (CM) with hand weeding, and CM with no weeding. Cowpea was seeded in July in 76 cm beds and irrigated with buried drip line. Two weeks prior to transplanting peppers, irrigation water was turned off to dry cowpea plants. In September, cowpea was cut at the soil-line and mulch returned the bed top. Pepper plants were transplanted into mulch and fertilized through drip line. During the season at two-week intervals, number of weeds emerged and pepper plant heights were measured. Additionally, at harvest in December, fruit production, pepper plant dry weight, and weed dry weight were measured. Fewer weeds emerged in CM compared to BG. At harvest, weeds emerged in
non-weeded CM were reduced 80 and 90% compared to non-weeded BG for 1997 and 1998, respectively. Weed dry weights in non-weeded CM were 67 and 90% less than weed dry weights in non-weeded BG over the same period. In 1997 and 1998, respectively, pepper plants in CM produced 202 and 156% more dry weight than in BG. Pepper plants in CM produced more fruit weight than in BG with similar fruit size. CM provided season long weed control without herbicides while promoting plant growth and fruit production compared to the BG system.
Impacts
Enhancing crop and cropping system characteristics to control weeds has wide-ranging consequences, including: reduction in pesticide use, new market for crops that can now be grown as organic certified, provides an advantage for limited-resource, ethnically diverse growers, better use of natural resources by lowering off-farm impact of agriculture.
Publications
- Hutchinson, C.M. and M.E. McGiffen. 2000. Cowpea cover crop for weed control in desert bell pepper production. HortScience. In press.
- McGiffen, M.E., Jr., and Ogbuchiekwe, E.J. 2000. Ethephon increases carotene content and deepens root color of carrots. HortScience.
- McGiffen, M.E., Jr. 1999. Wearing down weeds, p. 32B-32D. In Greenleaf, C. (asst. ed.), Pest Management. American Veg. Grower. May 1999.
- McGiffen, M.E., Jr. 1999. Can mulch replace herbicides? In Cunningham, C.J. (ed.), Peppers. J. Calif. Vegetable 4(3): 23.
- McGiffen, M.E., Jr. and Cudney, D. 1999. Yellow and purple nutsedge. In Greenleaf, C. (asst. ed.), Pest of the Month. Amer. Veg. Grower. April 1999, p. 37.
- McGiffen, M.E., Jr. and Cundye, D. 1998. Wild radish. In Greenleaf, C. (asst. ed.), Pest of the Month. Amer. Veg. Grower. October 1998, p. 60
- Hutchinson, C.M., Becker, O., and McGiffen, M.E., Jr. 1999. Methyl Iodide: An effective fumigant. In Cunningham, C.J.(ed.), Carrots. J. Calif. Vegetable 4(1): 20-23.
- McGiffen, M.E., Jr. 1999. California production update. In Bush, K. (ed.), Convention Reports: Great Lake Vegetable Growers Convention. Carrot Country, Spring 1999, p. 14.
- McGiffen, M.E., Jr. 1999. Researchers hope going green will get great results. In Tsai, E. (ed.), UCR Highlander. March 9, 1999, p. 7.
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Progress 01/01/98 to 12/01/98
Outputs
Cowpea (VIGNA UNGUICULATA, var. Iron Clay) was investigated as a cover crop mulch for weed control in a desert pepper (CAPSICUM ANNUM, var. Keystone) production system. Pepper production treatments included weeded cowpea mulch plots (CPW), cowpea mulch plots with no weed control (CPNW), weeded conventional bare-ground plots (BGW), and conventional bare-ground plots with no weed control (BGNW). The experiment was arranged in a randomized complete block design with four replications. Cowpea was planted in double rows centered on drip tape on July 7, 1997. On September 2, 1997, irrigation was shut-off to kill the cowpea. After 13 days, cowpea was cut at the soil line, placed on top of the bed, and pepper plants transplanted on 30 cm spacing. Weed number, pepper plant height, and cowpea dry weight were recorded over the season. On December 18, 1997, weed number, weed weight, and pepper plant weight were recorded. Cowpea dry weight decreased from 610 g/m at pepper
transplanting to 288 g/m at pepper harvest. Cowpea mulch reduced weed emergence in the CPNW treatment compared to the BGNW treatment by 95.4, 88.1, 92.2, and 80.3% at 14, 35, 57, and 94 days after transplanting, respectively. Total weed weight was significantly reduced from 37.1 g/m in the BGNW treatment to 12.2 g/m in the CPNW treatment. Pepper plants were significantly taller in the CP treatments compared to the BG treatments throughout the season. Pepper plant dry weight in the CPW and CPNW treatments was significantly higher than in the BGNW treatment.
Impacts
(N/A)
Publications
- HUTCHINSON, C.M., MCGIFFEN, M.E., OHR, H.D., SIMS, J.J., and BECKER, J.O. 1999. Evaluation of Methyl Iodide as a Soil Fumigant for Root-knot Nematode Control in Carrot Production. Plant Disease 83
- HUTCHINSON, C.M., MCGIFFEN, M.E., OHR, H.D., SIMS, J.J., and BECKER, J.O. 1998. Efficacy of Methyl Iodide Soil Fumigation for Control of Meloidogyne incognita, Tylenchulus semipenetrans, and Heterodera
- HUTCHINSON, C.M. and MCGIFFEN, M.E., JR. 1998. Mulch Impedes Weeds, Aids Crop Growth. 1998. IPMnet NEWS, No. 61, January, 1999. (Contact Information: A.E. Deutsch, Editor, IPMnetNUZ@ bec.orst.edu). In
- HUTCHINSON, C.M. and MCGIFFEN, M.E., JR. 1998. Methyl Bromide Phase-Out Date Changes in U.S. Weed Control Notes Vol. 98, No. 2,
- HUTCHINSON, C.M. and MCGIFFEN, M.E., JR. 1998. Cowpea Cover Crop Controls Weeds and Enriches Soil. Weed Control Notes Vol. 98, No. 2,
- HUTCHINSON, C.M. and MCGIFFEN, M.E., JR. 1998. Use of a Cowpea Cover Crop for Weed Control in Desert Bell Pepper Production. Calif. Vegetable Grower. In Press.
- HUTCHINSON, C.M., MCGIFFEN, M.E., and BECKER, J.O. 1998. Methyl Iodide, A Potential Replacement for Methyl Bromide Fumigation. Calif Vegetable Grower. In Press.
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Progress 01/01/97 to 12/01/97
Outputs
1) Soil Physical Factors Affect Methyl Iodide and Methyl Bromide Efficacy: Production and importation of methyl bromide is scheduled to be banned by 2001. Methyl iodide was evaluated as a possible replacement soil fumigant. The effects of soil moisture, temperature, soil texture, and fumigation time on the efficacy of methyl iodide for the control of weeds, pathogens, and fungi were characterized and compared with that of methyl bromide. The optimal soil moisture for methyl iodide in sandy soils was at 14% water content (w/w). Greater efficacy was obtained when the temperature during fumigation was above 20(degree)C. Compared to methyl bromide, the efficacy of methyl iodide was more consistent in different soils. Time to 100% mortality of weeds was 24 h for methyl iodide fumigation and 36 h for methyl bromide when 200 micro-moles of fumigant was used. Methyl iodide was consistently more effective than methyl bromide across the range of environmental factors tested. In
terms of application technology and spectrum of activity, methyl bromide can be directly replaced with methyl iodide. 2) Weed Management in Horticultural Crops: A conference on weed management was sponsored by both ASHS and WSSA in Orlando, FL, Feb. 6-7, 1997. The conference covered all of the horticultural crops, with expert speakers from across the country. A book based upon the conference was published that includes chapters on integrated weed management, herbicide use and mode of action, application technology, and management in specific crops.
Impacts
(N/A)
Publications
- BECKER, J.O., OHR, H.D., GRECH, N.M., MCGIFFEN, M.E., JR., and SIMS, J.J. 1997. Evaluations of methyl iodide as a soil fumigant in container and small field plot studies. Pesticide Sci. In press.
- ZHANG, W.M., MCGIFFEN, M.E., JR., BECKER, J.O., SIMS, J.J., and KALLENBACH, R.L. 1997. Dosage response of weeds to methyl iodide and methyl bromide. Weed Res. 37:181-189.
- ZHANG, W., MCGIFFEN, M.E., JR., BECKER, J.O., OHR, H.D., SIMS, J.J., and CAMPBELL, S.D. Effect of soil physical factors on methyl iodide and methyl bromide fumigation. Pesticide Sci. In press.
- MCGIFFEN, M.E., JR. (ed.). 1997. Weed Management in Horticultural Crops. ASHS Press, Alexandria, VA. 139 p.
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Progress 01/01/95 to 12/30/95
Outputs
WEED TOLERANT CROPS: While there are published reports of varietal differences in competitiveness with weeds, no crop varieties have been developed specifically for tolerance to weed interference. We explored several methods that mechanistically compare potential sources of tomato varietal tolerance to purslane, velvetleaf, and black nightshade: 1) The influence of canopy structure and development was studied with a wide range of crop germplasm and three weed species with distinctly different growth habits. Leaf expansion rate and other morphological characters were used to select varieties for more detailed study of competitiveness. 2) Replacement series experiments with selected cultivars found that purslane and other weeds can adapt to avoid competition. The greatest varietal differences in competitiveness were with nightshade species that had a canopy structure similar to tomatoes. METHYL IODIDE: We developed a direct replacement for methyl bromide as a soil
fumigant. Studies with weeds, pathogens, and nematodes found it to be at least as effective as methyl bromide. Further, it has a low potential of harming the ozone layer, and appears to have enhanced worker safety.
Impacts
(N/A)
Publications
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Progress 01/01/94 to 12/30/94
Outputs
Weed tolerant crops: No crop varieties have been developed specifically for tolerance to weed interference. We explored several methods that mechanistically compare potential sources of tomato varietal tolerance to purslane, velvetleaf, and black nightshade: 1) The influence of canopy structure and development was studied with a wide range of crop germplasm and three weed species with distinctly different growth habits. 2) Replacement series experiments with selected cultivars found that purslane and other weeds can adapt to avoid competition. The greatest varietal differences in competitiveness were with nightshade species that had a canopy structure similar to tomatoes. Field tests of methanol as a crop yield enhancer: A 1992 article by Nonomura and Benson (Proc. Natl. Acad. Sci. 89: 9794-9798) reported increased yield and drought tolerance in a wide range of C3 species following foliar applications of methanol. To test the validity of the reports, we applied methanol
with and without nutrients to a wide range of crops across California following Nonomura and Benson's (1992) protocol. Crops included watermelon, creeping bentgrass, lemons, savoy cabbage, carrots, romaine lettuce, radish, wheat, corn and peas. To test whether methanol improved drought tolerance, the savoy cabbage and watermelon experiments included both reduced and full irrigation. In no case was yield increased or drought tolerance attributable to methanol treatment.
Impacts
(N/A)
Publications
- FORCELLA, F., BUHLER, D.D, and MCGIFFEN, M.E., JR. 1994. Pest management and crop residues, p. 173-189. IN Hatfield, J.L. and B.A. Stewart (eds.), Crop Residue Management. Advances in Soil Science, Lewis Publ., Chelsea, MI.
- HARTZ, T.K., MAYBERRY, K.S., MCGIFFEN, M.E., JR., LESTRANGE, M., MIYAO, G., and BAAMEUR, A. 1994. Foliar methanol application ineffective in tomato and melon production. HortScience 29: 1087.
- MCGIFFEN, M.E., JR., PANTONE, D.J., and MASIUNAS, J.B. 1994. Path analysis of tomato yield components in relation to competition with black and eastern black nightshade. J. Amer. Soc. Hort. Sci. 119: 6-11.
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