Progress 01/01/11 to 12/31/11
Outputs
OUTPUTS: Since my 1999 text on managing the replant problem (RP) our focus has been on large scale evaluation of potential strategies and tactics beyond soil fumigation. Starve and Switch refers to applying an effective systemic herbicide followed by one full year of fallow then switching to a rootstock of very different parentage having broad nematode resistance. For the plum industry the starvation process is important when the previous rootstock was Nemaguard peach, Prunus persica, and the intention is to replant with another Nemaguard or P. persica. However, switching the rootstock to something other than Prunus persica, when following Nemaguard, can be the most valuable tactic when replanting without soil fumigation. Our best example is from the Harrow Blood x Okinawa cross, HBOK series, where both peaches in the cross are P. persica and switching from Nemaguard to HBOK rootstocks is inadequate. By contrast, switching to a peach x almond hybrid, such as Okinawa x Titan, Hansen 536, provides enough change in the parentage to replant after Nemaguard and achieve very good first first-year growth. Since most of the plum industry is planted on Nemaguard Peach and most growers prefer a more dwarfing rootstock Krymsk 1, Prunus tomentosa x P. cerasiferae, is a good choice. It is also the only source of root lesion resistance available to growers of Prunus. A weakness common to Krymsk 1 and Hansen 536 is their susceptibility to ring nematode thus these two tactics are only useful in medium textured soils where ring nematode build-up is minimal. In coarser-textured soils HBOK1 is comparable to Viking against ring nematode but neither is completely adequate for switching. This is where we need spot or strip fumigation or two years without Prunus before replanting. Meanwhile, for the walnut industry a history of Juglans hindsii can be eliminated by planting of Juglan cathayensis, J. regia or J. microcarpa parentage. A fall application of Garlon herbicide followed by fallow or growing of non nematode hosts will suffice. Tolerance or preferably resistance to endoparasitic nematodes is also essential for these rootstocks to ever become useful. Fortunately, there is nematode resistance within Juglans. During their 8th, 9th and 10th years the yields of Chandler on nematode susceptible paradox seedlings, DN, were significantly reduced while those having some nematode resistance, NX, produced good yields following mediocre soil fumigation. When it comes to other potential genetic sources of nematode resistance 10 seedlings of J. cathayensis imported from China still appear resistant to P. vulnus and M. incognita in their third year. This source has provided a mother-lode of resistant material but it is also notable that the trees direct from China appear to be relatively low in vigor. Additional years of tree evaluation will be important to assess durability of this resistance. We have also identified a second source of nematode resistance mechanisms in RX032 which is J. microcarpa. PARTICIPANTS: Partners in this research have included the California Walnut Research Board, California Tree Fruit Agreement plus collaborators Chuck Leslie at UC Davis and David Ramming of USDA-ARS Parlier TARGET AUDIENCES: Growers of California stone fruits and walnuts were the target of these studies. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
The Agricultural Research Service, United States Department of Agriculture, announces the release for propagation of the grape rootstock cultivar Demko10-17A. It is being released to provide a highly nematode resistant grape rootstock. Demko10-17A resulted from the cross Edna x male Simpsonii made by Dr. Charles Demko, Atloon, Florida. It was obtained by John Weinberger about 1957 and grown in plots at the US Department of Agriculture research station, Fresno, CA. Demko10-17A has been tested in the San Joaquin Valley of California as a grape rootstock for table, raisin and wine grapes. Demko 10-17A readily roots from dormant cuttings, similar to Harmony, Freedom, Teleki 5C and P1103. In greenhouse and field tests Demko 10-17A has been resistant to Meloidogyne spp. nematodes, including M. arenaria pt. Freedom and Harmony, M. incognita, M. chitwoodi, M. javanica, M. spp. pt. Ramsey, and mixed Meloidogyne spp. In additional greenhouse tests Demko 10-17A has been resistant to P. vulnus and T. semipenetrans. Resistance to Xiphinema index is good and equal to Freedom and slightly better than Harmony and O39-16. Resistance to X. americanum is variable depending on the population. Demko 10-17A was found to be intolerant of grapevine fan leaf virus. Demko 10-17A has shown tolerance to root rejection in a Gilroy, California field trial. This vineyard was replanted after own-rooted Chardonnay into non-fumigated as well as fumigated soil. In greenhouse tests, Demko 10-17A was resistant to phylloxera collected from Ruby Seedless in Fresno County, California. Syrah on Demko 10-17A yielded the same as Freedom and own root vines with vigor less than Freedom and P1103 but more than own root. Brix levels were similar to Freedom and own root but less than P1103. In the Thompson Seedless trial, Demko 10-17A yielded less than Harmony and own root but was more vigorous than both. In table grape trials in Kern County of California, Demko 10-17A produced large berries with yields similar to Freedom, except in a Thompson Seedless trial. Yield of Princess was increased in years of early bunch stem necrosis. Vigor was similar to or less than Freedom. Potassium levels have been consistently lower than Freedom.Demko10-17A was indexed by the Foundation Plant Services (FPS), University of California, Davis, CA 95616 and found free of known viruses. Certified virus free material may be requested from FPS. Genetic material of this release has been deposited in the National Plant Germplasm System where it is available for research purposes, including breeding and development of new cultivars. The Agricultural Research Service has no plants of Demko10-17A available for distribution. Limited quantities of cuttings may be obtained by writing David W. Ramming, USDA, Agricultural Research Service, Crop Diseases, Pests and Genetics Research Unit, 9611 South Riverbend Avenue, Parlier, CA 93648. It is requested that appropriate recognition be made if this germplasm contributes to the development of a new breeding line or cultivar.
Publications
- No publications reported this period
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Progress 01/01/10 to 12/31/10
Outputs
OUTPUTS: In the most recent year this PI delivered 22 oral presentations to a variety of audiences on the subject of Movento as a new post-plant nematicide. Presentations included raisin growers at Easton, CA; walnut growers at Bodega Bay, CA; other nematologists at Boise, ID; wine grape growers at Lodi, CA; almond growers at Kerman, CA; pest control advisors at Anaheim, CA; pest control advisors for almond and walnut at Modesto, CA; students at Fresno State University; and cling peach growers at Modesto, CA. Presentations on the subject of Starve and Switch, a potential alternative to soil fumigation, were presented to walnut growers at Bodega Bay; farm advisors for almond and walnut during a field tour; pest control advisors for Fresno and Madera, CA; and cling peach growers at Modesto. In addition, there were six field viewings of our three large field trials on the subject of Starve and Switch being conducted at the Kearney Ag Center near Parlier CA. These viewings included visits during the Statewide Nematology Workshop; members of various high school classes from the San Joaquin Valley; Cal Poly University class in vine pest management; and two visits by stone fruit grower groups. There was also a presentation on methyl iodide for various crops at San Francisco, CA; discussion on the need for new genetic material for the walnut industry at UC Davis; the replant value of Movento for control of Phylloxera as well as nematodes at Fresno, CA and a presentation on a new grape rootstock planting near Lompoc, CA. Audiences for these presentations ranged from 10 to 300 with a mean of approximately 125. Each presentation provided technical information usually the product of study by this PI. PARTICIPANTS: This research effort was carried out with the assistance of two technical assistants, Stephanie Kaku and Tom Buzo, plus Safdar Anwar an occasional visiting scientist from Pakistan. We also have linkages to Gary Van Sickle of the California Stone fruit Agreement, Bob Curtis of the California Almond Board, Ross Jones of California Table Grape Commission, David Ramos of the California Walnut Board, Jim Mueller of Dow Agrisciences, Curt Engle of Paladin Nematicide, Gary Braness of Bayer Chemical and Tim Kingston of the Gas Technology Institute. The above listed project leaders receive timely updates on our research activities. These reports are necessary to advise interested parties or funding groups of our progress. TARGET AUDIENCES: Parties interested in these studies are those interested in perennial crops and their production with minimal use of soil fumigants. My audience ranges from growers of major crops such as grape, almond and stone fruit to minor crops such as pomegranate and kiwifruit. However, it is only the growers of major crops who are able to fund our research effort. Growers of minor crops do participate in our information delivery sessions for general information on the subject of nematode management. State and Federal regulatory groups as well as California nursery industries also participate in our information delivery. PROJECT MODIFICATIONS: Focus of our long-lasting field trials can change on occasion. Last year we changed the focus of a ten year old walnut planting that had been focused on rootstock evaluation to a trial involving use of Movento as a post plant nematicide. This was because one of two rootstocks being compared began slipping in yield and thus the site became a perfect setting for field evaluation of our newest post plant nematicide. In a second experiment half the trees in a two year old almond replant were removed to evaluate a new rootstock with great potential as a trap crop against root lesion nematode. These changes are major to the field site but they all fit within our general research umbrella of nematode management for California's perennial crops.
Impacts
Potential end products of these studies include one new peach rootstock, one new almond rootstock, two new walnut rootstocks plus the benefits and limitations of Movento as a new nematicide. The latter nematicide, which was previously only known as an insecticide, now has a California label for for suppression of plant parasitic nematodes.
Publications
- Zasada, I. A., J. M. Halbrendt, N. Kokalis-Burelle, J. LaMondia, M.V. McKenry and J. W. Noling. 2010. Managing Nematodes without Methyl Bromide. Annu. Rev. Phytopathol. 48:311-328.
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Progress 01/01/09 to 12/31/09
Outputs
OUTPUTS: Since coining the term Starve and Switch, this lab has initiated large field trials to quantify its value as an alternative to soil fumigation. Growth of two almond scions on three Prunus rootstocks was evaluated in fumigated, non fumigated and a starve and switch setting. Starvation is accomplished by application of systemic herbicide to old trees and waiting one year. Switching is accomplished by choosing rootstocks with tolerance to the rejection component. Planted in spring 2009 and measured in fall 2009, all growth measurements indicated tree growth after Telone fumigations grew significantly larger trees than those in Starve and Switch which grew significantly larger trees than those in the non fumigated blocks. Viking rootstock grew trees of significantly greater height, weight and trunk size than those on nemaguard rootstock. Thus,Viking rootstock following Nemaguard rootstock appears to be a significantly better rootstock to switch to compared to Nemaguard following Nemaguard. HBOK 50 rootstock was a poorer rootstock choice than Nemaguard but this was significant only when measuring tree height. Across this almond trial Nonpareil scion outgrew Carmel scion regardless of soil treatment. Nematodes were not a problem in this orchard as the major component of concern was the rejection component of the replant problem. First-year tree growth was also collecded from a plum replant setting. The single scion was Owen T plum grafted onto five different rootstocks. Nematodes were not a problem in this planting but the rejection component and the presence of crown gall was of concern. There was no significant difference in tree growth achieved from Telone fumigated compared to our starve and switch alternative. Trees in the non fumigated check were signifcantly reduced in size when the rootstock was Nemaguard or Krymsk 1 when following Nemaguard rootstock. Rootstocks HBOK 32, HBOK 28 and HBOK 50 showed a similar but non significant trend in the non fumigated blocks. The rejection component of the replant problem is less intense in this field trial as the starve and switch approach provided tree growth at least as good as that in the fumigated. However, Krymsk 1 rootstock has become almost 100% infected with large crown galls whether fumigated or not. Starve and switch continues to hold promise as an alternative to soil fumigation but today our preferred rootstock for this strategy remains limited to Hansen 536 in sandy loam soils. The value of Viking rootstock is in sandier soils where ring nematode is problematic and Hansen 536 too susceptible. PARTICIPANTS: Project oversight via California Tree Fruit Agreement, Growth evaluations from Reedley Community college intern students and visitations by California Dept. of Pesticide Regulations and occasional visitors TARGET AUDIENCES: Students included two Haitians from Reedley College and two Germans from the Agricultural Government sector of Germany. Some growers have visited but that will increase in 2010. PROJECT MODIFICATIONS: No major changes have occurred in our research approach
Impacts
Proof of concept is being tested in large, complex field trials. There are four major components to the replant problem and each of the components needs field assessment if fumigants are to be replaced by non fumigant approaches. Population levels of known pathogens can be quantified ahead of planting to assist decision-making relative to choice of rootstock. Intensity of the rejection component is not known ahead of planting but we previously indicated that 85% of its intensity can be overcome by starving the prevailing soil ecosystem. Unfortunately, our tool box of tactics is meager and greater effort is needed to identify rootstocks with tolerance to the rejection component. Appearing to be on target with our starve and switch approach, these field trials will become the focus of field days as well as an indicator that additional field trials are needed. Our recent identification of a walnut species having very different Juglans parentage that also has resistance to root lesion and root knot nematodes is in need of field evaluation. Our first tests involving starve and switch for walnut rootstocks will be planted in 2010 using field treatments similar to those identified in the 2009 field trials except this replant setting also contains root lesion nematodes.
Publications
- Bent, E., A. Loffredo, J. Yang, M. McKenry, J. O. Becker & J. Borneman. 2009. Investigations into peach seedling stunting caused by a replant soil. FEMS Microbiol Ecol 68:192-200.
- Anwar, S. A. and M.V. McKenry. 2008. Induction of resistance and susceptibility in tomato by two Meloidogyne incognita populations. JON 40(4):276-280.
- McGranahan, G. H., W.P. Hackett, J. McKenna, C.A. Leslie, T. Buzo, S. Kaku and M. V. McKenry. US Plant Patent #20080820618,A new clonal rootstock for walnuts (VX211). Patent applied for Dec 25, 2008.
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: In 2008 we initiated three large orchard trials to quantify the value of our Starve and Switch approach as an alternative to soil fumigation prior to replanting perennials. One of the trials involves replanting plum after plum on Nemaguard, another is replanting almond after Nemaguard rootstock and a third is replanting walnut after walnut. To initiate such trials means we have new tools in our tool box for handling the replant problem associated with each of these crops. The grower cost associated with starve and switch includes: one full year of waiting after tree removal, the cost of killing old roots with a systemic herbicide and various costs associated with planting on rootstocks which may not be familiar or in abundance. For the grape industry we suggest the following model: Apply glyphosate herbicide to cut trunks only in February or March > remove vines and wait one year > plant on 10-17A rootstock which provides tolerance to the rejection component of the replant problem (RP) while providing broad nematode resistance. For plum replanting we are testing a model that involves use of dwarfing (50%) rootstocks: Apply glyphosate to trunks or leaves in July to November > remove trees and wait one year > replant on Krymsk1 rootstock for tolerance to nematode feeding as well as resistance to Pratylenchus vulnus and adequate resistance to Meloidogyne spp. in medium-textured soils as well as tolerance to the rejection component of RP. Krymsk 1 rootstock does not possess resistance to Criconemoides xenoplax nematode but several HBOK (20% dwarfing) selections do offer protection. For almond replanting our model is: Apply glyphosate to trunks or leaves between July and November > remove trees and wait one year > replant on medium to fine textured soils using Hansen 536 or in the presence of C. xenoplax utilize one of the vigorous HBOK rootstocks that offers resistance to C. xenoplax. For replanting walnut after walnut our model is: Apply triclopyr herbicide to cut trunks between harvest and mid November > remove trees and wait one year > replant on Juglans cathayensis which offers resistance to P. vulnus and Meloidogyne spp. and probably offers tolerance to the rejection component. This Juglans cathayensis selection number 21 is only a model at this time because its graft affinity with Chandler scion is only 50%. One year of starving the old soil ecosystem plus switching to a rootstock having very different parentage is our alternative to pre-plant soil fumigation. Our tool box is rather sparse at this time but field evaluation of these model systems could provide the impetus to screen rootstocks for tolerance to the rejection component of RP as well as known soil pests. PARTICIPANTS: Individuals involved with these studies are listed as authors or co-authors in the publications section of this report. Partner organizations have included various commodity groups in California including Walnut, Table Grape, Stone Fruit and Almond boards of California. Research funding for this project has never emanated from USDA ARS. In summer 2009 through 2010 there will be ample opportunities for demonstration of the value of starve and switch versus soil fumigation. TARGET AUDIENCES: Each year 24 presentations are made by the PI to other researchers or lay public and the subject of these studies is in half those reports. Perhaps the most persuasive reason for growers to change is the fact they cannot use fumigants in certain locations where they need to use them. This research pertains to a large issue and the audiences are attentive. PROJECT MODIFICATIONS: There have been no major changes in our research plan. There have been findings that added to our overall tool box of information.
Impacts
For replant sites involving grape, plum, peach, nectarine, almond and walnut we now have model systems that could become an alternative to soil fumigation. In large field settings three of these models will now receive evaluation in comparison to soil fumigation or no treatment at all. These tests are the product of years of small plot field screening for each of the different tools plus we already have data to indicate our methods for grape and almond can perform adequately in at least one California location. Currently, methyl bromide fumigant is quite expensive and being phased out while Telone fumigant is limited by 50% at least for 2009. Our findings will become more clear in next year's report but at this time growers now have a potential alternative in settings where no other treatments are currently available.
Publications
- McKenry, Michael, Tom Buzo and Stephanie Kaku. 2008. Cropping Systems for Sustainable Nematode Management of Tree and Vine Crops. Fifth International Nematology Conference July 13-18 Brisbane, Australia
- Bent, E., A. Loffredo, M. V. McKenry, J. O. Becker and J. Borneman. 2008. Detection and investigation of soil biological activity against Meloidogyne incognita. JON 40(2): 109-118.
- Cohen, S. and T. Martin. 2008. UCIPM Field Fumigation Study Guide. Technical Editor: M. L. Flint. Technical Writers: H. Ajwa, A. Gallo, D. Lawson, M. McKenry, P. Niday, R. Segawa, T. Stone and Mac Takeda. UCIPM/DPR 123pp / 8 chapters http://www.cdpr.ca.gov/docs/license/lcpubs.htm
- Wang, K.-H., B. S. Sipes, D. Schmitt, An MacGuidwin, M. McKenry, T. J. Bliss, B. Kerry and S. Costa . 2008. Plant Nematological Contributions to Phytopathology. APSnet Feature Story, November.
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Progress 01/01/07 to 12/31/07
Outputs
In 2007 we simplified the five-point program indicated in this title. Our current term for this alternative to soil fumigation is "Starve and Switch". "Starve the soil ecosystem, switch rootstock parentage" provides growth of replanted trees and vines that can be comparable to that of pre-plant fumigation. Our usual approach to starving the soil ecosystem has been to cut trunks of Prunus trees and paint the cut surface with glyphosate. In 2007 a 2% solution of Roundup herbicide was carefully sprayed at low pressure to one side of each tree row and then to the opposite side without permitting droplets to reach above the tree tops. This procedure provided excellent kill of plum and peach tree root systems without apparent damage to adjacent trees located 1.5m away. Leaves at the tree tops were the last to necrose and abscise. We do not intend to evaluate such sprays to walnuts because drift problems associated with Garlon are well known. Treatments such as these plus a
full year of fallow appear to provide adequate starvation of the prevailing soil ecosystem so that the rejection component of the replant problem can be largely overcome. In our effort to switch away from Nemaguard rootstock we have selected Krymsk1, and several selections of the HBOK rootstocks, plus we have had a long interest in Hansen 536. Krymsk1 provides 50% dwarfing, adequate resistance and tolerance to P. vulnus and when following Nemaguard carries adequate resistance to M. incognita. This rootstock does not appear to offer adequate resistance to C. xenoplax so its use will not be suggested within sandy soils. Use of this rootstock will likely be limited to plum and perhaps apricot scions. Based on a six-year replicated field trial, HBOK-1 carries resistance to M. incognita and C. xenoplax that is equivalent or better than that of Viking, Lovell or Guardian. HBOK-50 carries resistance to M. incognita and does not support P. vulnus populations as high as those on Nemaguard.
Hansen 536 provides 20% more vigor than Nemaguard, is highly susceptible to C. xenoplax, but a poorer host of P. vulnus when compared to Nemaguard. Use of this stock will be limited to almonds as the scion in sandy loam soils, but not sands. With Juglans rootstocks the Paradox hybrid clone, VX211 is now available to public and will out-perform all other Paradox sources currently available. Several more clones including UZ229 and RX032 which host fewer P. vulnus are still under examination. For our "starve and switch" approach the finding of Juglans cathayensis holds greater promise than all the Juglans selections listed above.
Impacts
For walnut growers VX211 is now available. It carries high vigor and some tolerance to nematode damage because of a resistance mechanism that restricts P. vulnus feeding to being ectoparasitic. We have also identified a very different walnut source from China that appears to carry resistance to P. vulnus and M. incognita. The HBOK series of rootstocks appears to provide several opportunities as an alternative to Nemaguard. Krymsk 1 will receive field evaluation as an alternative to Nemaguard specifically for plum growers.
Publications
- Sadfar A. Anwar and M. V. McKenry 2007. Variability in reproduction of four populations of Meloidogyne incognita on six cultivars of cotton. JON 39 (2):105-110
- McKenry, M. V. and S. A. Anwar. 2007. Virulence of Meloidogyne spp. and induced resistance in grape rootstocks. JON 39 (1):50-54. M. V. McKenry, and Safdar A. Anwar. 2006. Nematode and grape rootstock interactions including an improved understanding of tolerance. JON 38 (3):312-318.
- McKenry, M. V., T. Buzo and S. Kaku. 2007. Replanting vineyards without soil fumigation. Proceedings of International Conference on Methyl Bromide Alternatives and Emission Reductions. Oct 28-31. San Diego, CA Anwar, S. A., and M. V. McKenry. 2006. Induced Resistance: an innovative approach to nematode management. Pp 231-237. Proceedings of International Symposium on Sustainable Crop Improvement and Integrated Management. University of Agriculture, Faisalabad, Pakistan on September 14 to 16, 2006.
- Anwar, S. A., M. V. McKenry, and N. Javad. 2006. The root-knot nematodes: destructive pests of crops. Pp 216-222. Proceedings of International Symposium on Sustainable Crop Improvement and Integrated Management. University of Agriculture, Faisalabad, Pakistan on September 14 to 16, 2006.
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Progress 01/01/06 to 12/31/06
Outputs
We now have 14 Prunus rootstocks of interest as we search for an alternative to Nemaguard rootstock. These rootstocks have been screened for resistance to Meloidogyne incognita, Pratylenchus vulnus and Mesocriconema xenoplax and no single rootstock has shown resistance to all three nematode genera. Our work with M. xenoplax will not be completed until fall 2007. For stone fruits our interest is in rootstocks that will impart vigor similar to or less than that of Nemaguard. For almonds our search is for stocks having vigor similar to or greater than Nemaguard. From the nematode perspective potential new rootstocks for stone fruit include Empyrean 2, Torinel, Flordaguard, Viking, Krymsk 1 and Cadaman. New rootstocks for almond include Monegro, Cadaman, Viking, Bright's Hybrid-4, Empyrean 1, Hansen 536 and Flordaguard. In 2006 the above listed rootstocks were evaluated for their first-year tolerance to nematode feeding plus their tolerance to the rejection component of
the replant problem. Krymsk 1 is the only stock of 42 screened with resistance to P. vulnus. This dwarfing rootstock also exhibits tolerance to first-year feeding by M. incognita and P. vulnus, although its terminal roots are susceptible to M. incognita. Fumigation may not be needed when Krymsk 1 is replanted after Nemaguard. Myrobalan 29C, a well-known rootstock, also exhibited tolerance to nematode feeding but the others listed above did not. Presence of tolerance to the rejection component was confirmed for Hansen 536. In 2006 we provided the first report of two grape rootstocks, O39-16 and 10-17A that in one five-year field trial yielded the same whether fumigated or not when following Vitis vinifera. Yield of seven other rootstocks was half that of fumigated vines when soil was not fumigated. In 2006 we reported on a new paradox walnut rootstock clone, VX211, which exhibits high vigor, slight resistance to P. vulnus, and tolerance to Meloidogyne incognita. In a five year
commercial evaluation we reported that a pre-infection mechanism in NX seedlings of paradox walnut were providing improved growth when planted into soils that had received a relatively poor pre-plant fumigation. We are also evaluating the resistance of P. vulnus and M. incognita within own-rooted Serr clones. These English walnuts were shown to resist M. incognita in an earlier field evaluation and they perhaps support fewer P. vulnus. This is the first of about 15 English walnut cultivars that has shown any nematode resistance. Eight different Juglans spp were obtained in 2006 from the National Repository at Davis and are now being screened for resistance to P. vulnus and M. incognita. Eight products are now receiving commercial evaluation for their nematicidal benefit in three vineyards, one citrus orchard, and one nectarine orchard. Performance of these products ranges from 10% to 90% nematode relief in the first year of study. Products receiving evaluation include fosthiazate,
Cordon, NatureCur, Integrate, Quillaja, BY Expt. Admire, and Paecilomyces lilacinus. Two years of yield evaluation are necessary.
Impacts
For a variety of perennial crops we have identified non-fumigation procedures to avoid the rejection component of the replant problem. These procedures have greater limitations than use of fumigants but they show a new direction is possible and workable across a variety of crops. We have also identified some new sources of nematode resistance in walnut, grape, stone fruits and almond. We are ready for commercial evaluations in the crops listed except walnut. For walnut we have new fumigation strategies and chisel shanks that are in need of field evaluation.
Publications
- Becker, J. O., M. McKenry, M. Freeman, R. Duncan, E. Bent, and J. Borneman. 2006. Bioassays for detection and analysis of Prunus replant suppression, International Conference on Methyl Bromide Alternatives and Emission reductions. Nov. 6, 2006. Orlando Florida.
- Buzo, T., M. McKenry, and J. Hasey. 2006. Interaction of Juglans Species with Pratylenchus vulnus and Meloidogyne incognita. Proceedings of the Fifth International Walnut Symposium. Acta Horticulturae 705:417-423.
- Cao, T., McKenry, M. V., Duncan, R. A., DeJong, T. M., Kirkpatrick, B. C., and Schackel, K. A. 2006. Influence of ring nematode infestations and calcium, nitrogen, and indoleacetic acid applications on peach susceptibility to Pseudomonas syringae Phytopathology 96:608-615.
- McKenry, M. V. 2006. Nematicidal value of grape rootstocks in field settings. In San Joaquin Valley Table Grape Seminars Feb 22, 2006 Pp 18-23. McKenry, M. V. and S. A. Anwar. 2006. Nematode and grape rootstock interactions including an improved understanding of tolerance. Journal of Nematology 38(3):312-318.
- McKenry, M., T. Buzo, and S. Kaku. 2006. Replanting stone fruit orchards without soil fumigation. International Conference on Methyl Bromide Alternatives and Emission Reductions. Nov. 6, 2006. Orlando, Florida.
- McKenry, M., S. Kaku, and T. Buzo. 2006. Development of a nematode-rootstock profile for Prunus spp. Journal of Nematology 38(2):282.
- Anwar, S. A. and M. V. McKenry. 2006. Induction of systemic acquired resistance and susceptibility in tomato by two Meloidogyne incognita populations. Journal of Nematology 38(2):259.
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Progress 01/01/05 to 12/31/05
Outputs
In 2004 and 2005 this PI began development of a Nematode/Rootstock profile for Prunus spp. Although 2 more years will be required a large data set is already available. Forty Prunus rootstock selections were collected from Russian, Italian, Spanish, French, and US sources. Twenty rootings of each selection were planted into sandy loam soil along with Pratylenchus vulnus, Meloidogyne incognita nematodes. Eighteen of the selections were placed into large sand tanks containing Mesocriconema xenoplax. Three standard trees were used for comparison, including Nemaguard, Lovell and Pistacia atlantica. The pistachio selection is resistant to P. vulnus and Meloidogyne spp. Nemaguard is the rootstock of choice in 90% of California's peach, plum, prune, nectarine, apricot and almond orchards. Nemaguard peach is quite sensitive to the rejection component when it is the replant, so we are searching for an alternative rootstock with comparable or improved nematode resistance. Our
overarching goal is to replace soil fumigation using a strategy of five steps and one of those steps is to plant on a rootstock having parentage different from Nemaguard. Thirty of the 40 Prunus rootstocks exhibited resistance to M. incognita; or fewer than 0.2 nematodes/gram of root. Apparently scientists from around the world have recognized that resistance to Meloidogyne spp is essential. Unfortunately, a number of these 30 selections had Nemaguard in their parentage, but not all. The only rootstocks offering resistance to P. vulnus were Pistacia atlantica, Krymsk 1 and Krymsk 2. The latter two did exhibit susceptibility to M. incognita but Krymsk 1 may be a useful reduced vigor alternative following Nemaguard. Two rootstocks exhibited moderate resistance (0.21 to 0.6 nematodes/gram of root) to P. vulnus plus resistance to M. incognita and they included Garnem (Garfi almond x Nemared) and Bright's Hybrid-4 (Titan almond x Nemaguard). Rootstocks exhibiting a P. vulnus host status
similar to or less than Nemaguard but without Nemaguard parentage included Hansen's 536, Flordaguard, Empyrean 2, and Torinel. Viking also fit into this latter group but has a small level of Nemaguard parentage. These are the findings of a two-year evaluation. Of 18 selections placed into soil infested with M. xenoplax no rootstock thus far has out-performed Lovell but Guardian, Pumiselect, and Bright's Hybrid -1 have come closest. In 2006 several of the stocks listed above and others are being planted into long-term studies involving numerous trees with and without nematodes. This will be an effort to confirm original findings while evaluating fruit and tree size imparted by each rootstock. Five field trials were initiated for evaluation of several new post-plant nematicidal agents. What is learned from these 3-year trials will broaden our capabilities for solving replant situations that involve a nematode component but rootstock resistance is unavailable.
Impacts
The replant problem of perennials is complex and we have previously identified four components including: 1) rejection component, 2) soil pest and disease component, 3) soil physical and chemical component and 4) a nutritional component. Proper soil ripping and fumigation solves all these components but future costs and availability of these tools makes them unsure. Our proposed alternative to soil fumigation is: a) systemic herbicide to old trunks, b) wait one full year, c) soil ripping, d) replant with rootstock of different parentage and e) a fertilizer program. Although our interests include all perennials our main focus has involved replanting of Vitis, Prunus and Juglans. Our efforts to improve rootstock availability in Prunus should provide us with the compliment of strategies and tactics needed to solve the replant problem of Prunus. The industries based on Prunus will become our model system to test the five-step program indicated above. We do not envision
successes everywhere but through proper diagnosis of prevailing field settings we will determine where the 5-step program has the potential for success. Success with post-plant nematicides would further enlarge our capabilities by providing a useful sixth step.
Publications
- T. Cao, R.A. Duncan, M.V. McKenry, K.A. Shackel, T.M. DeJong and B.C. Kirkpatrick. 2005. Interaction between nitrogen-fertilized peach trees and expression of syrB, a gene involved in syringomycin production in Pseudomonas syringae pv. syringae. Phytopathology 95:581-586.
- Holtz, B. A., T. Caesar-TonThat, and M. V. McKenry. 2005. Wood chipping almond brush and its effect on soil and petiole nutrients, soil aggregation, water infiltration, and nematode and basidiomycete populations. Options Mediterraneennes, Series A, Numero 63: 247-254.
- McKenry, M. V. October 2004. Progress in the Search for Methyl Bromide Alternatives for Stone Fruits. California Tree Fruit Agreement Research Report. Vol VIII-4 Pp1-2.
- Ferris, H., M.V. McKenry, B.A. Jaffee, C.E. Anderson, and A. Jurma. 2004. Population characteristics and dosage trajectory analysis for Mesocriconema xenoplax in California Prunus orchards. Journal of Nematology 36(4): 505-516.
- McKenry, M.V., D. Luvisi, S.A.Anwar, P. Schrader, and S. Kaku. 2004. Eight-year Nematode Study from Uniformly Designed Rootstock Trials in 15 Table Grape Vineyards. Am. J. Enol. and Vitic. 55: 218-227.
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