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United States Department of Agriculture

Agricultural Research Service


Location: Crops Pathology and Genetics Research

2012 Annual Report

1a. Objectives (from AD-416):
1. Develop, test, and demonstrate optimized integrated pest management (IPM) strategies for management of almond replant problem in Merced County without methyl bromide (MB). 2) Contribute to educational outreach to foster grower utilization of program findings in Merced County.

1b. Approach (from AD-416):
1. In collaboration with University of Calfornia Cooperative Extension, Merced, California, an almond replant trial (almond to be replanted after removal of old almond trees) will be conducted in Merced County at a commercial field site with sandy soil and a history of ring nematode infestation. 2. In collaboration with University of Calfornia Cooperative Extension, Merced, California, treatments designed to evaluate efficacy of fumigant alternatives to MB will be applied to replicate mainplots-- 8- to 11-ft-wide strips of the land centered over future tree rows (strip treatments) or to 5 ft x 6ft rectangles of land centered over future tree planting sites (a spot treatment). The strip treatments will include a non-fumigated control, a fumigated control (MB, 400 lb/treated acre), Telone II (340 lb/treated acre), Telone C35 (540 lb/treated acre). The spot treatment will include Telone C35 (540 lb/treated acre, equivalent to approximately 54 lb/orchard acre). All of the treatments will be applied in fall 2009, and selected fumigant treatments will be tested with and without preceding summer-long rotations with sudan grass (in the absence of sudan grass rotations, the ground will be cultivated or sprayed periodically to maintain it relatively free from weeds). 3. At least two treatments designed to evaluate efficacy of non-fumigant alternatives to MB will be applied to 5 x 6 ft subplots centered over future tree planting sites and within the main plots. The subplot treatments may include treatments with steam and Brassica seed meal, steam, Trichoderma formulations, and fungicide and oomycete treatments. 4. Tree trunk diameters, visual disease severity ratings, and nematode samples will be collected at least two times per year. 5. Educational outreach will be achieved via a UCCE/ARS-hosted field demonstrations day at the trial site in Madera County.

3. Progress Report:
Established in support of Objective #1 of the in-house project-which is to demonstrate alternatives to Methyl Bromide in key crop systems and regions dependent upon Methyl Bromide. The goal of this project is to develop, test, and demonstrate optimized IPM strategies for management of almond replant problems in Merced County without the use of Methyl Bromide. Follow up work was performed in October of 2010 for the fumigant trial established in January 2010. This included nematode sampling of plots, tree vigor evaluation, and trunk diameter measurements. All trees were evaluated for bacterial canker in late spring, a disease that commonly occurs in sandy soils with high nematode counts. Follow up work was performed throughout the year on the second fumigant trial within Merced County. This trial, established in 2011, included the evaluation of the pre-plant fumigant, steam, and tree site applied treatments. Observations of disease severity were taken throughout the year (2011). Nematode sampling was performed in October, 2011. End of year growth measurements were taken in January, 2012. A third site for studying the effects of fumigant alternatives was established in the fall of 2011 within Merced County at a commercial field site with sandy soil and confirmed presence of Ring Nematode. Fumigant treatments were applied in October, 2011 and include: steam (applied with tractor-mounted soil augers 90 cm diameter to a 60 cm depth, centered at tree planting sites [TPS]); soil mixing (achieved with backhoe in 1.5 x 1.5 x 1.5 m volumes centered at TPS); and soil fumigation (MB, or 1,3-dichloropropene [1,3-D], or 1,3-D plus chloropicrin [1,3-D:CP], applied with tractor-mounted shanks to row strips, spots, or broadcasted areas). The steam treatment heated the soil to over 200 degrees F and maintained a soil temperature of over 150 degrees F for at least 6 hours post treatment within the treated area. Plots contained one eight tree row of each variety (24 trees). The plot was established in a randomized block design with 5 blocks. Trees were planted in January, 2012 and were measured before they broke dormancy. The newly established trial included a main plot testing soil fumigants and steam spot treatments, and a second experimental plot testing fumigant alternatives, which included spot treatments of various products, soil disruption through the use of a backhoe, untreated control, and a C35 strip treatment. The C35 fumigant was applied using the row strip treatment described previously. Tree sites were excavated with a backhoe to an estimated volume of 64 cubic feet (4’x4’x4’ hole).Each treatment block consisted of eight replicate trees of five blocks. A field day showcasing the fumigant trial established in 2011 was held on June 1st, 2012. Over 150 growers, pest control advisors, and regulators attended and observed the effects on the various fumigant and steam treatments on tree growth. The meeting received great reviews and has raised awareness of fumigant alternatives to methyl bromide. This is planned to be repeated in 2013. Assistance was also provided for conducting measurements and sampling of previously established fumigant trials within Madera and Fresno counties.

4. Accomplishments

Last Modified: 07/21/2017
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