Location: Crops Pathology and Genetics Research
2012 Annual Report
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.