Author
Gao, Suduan | |
DOLL, D - University Of California - Cooperative Extension Service | |
QIN, R - University Of California | |
DANGI, S - University Of California | |
Gerik, James | |
HANSON, B - University Of California | |
Wang, Dong |
Submitted to: Meeting Proceedings
Publication Type: Proceedings Publication Acceptance Date: 10/9/2015 Publication Date: 11/8/2015 Citation: Gao, S., Doll, D., Qin, R., Dangi, S., Gerik, J.S., Hanson, B.D., Wang, D. 2015. Emission, pest control, and crop response in almond orchard soil fumigation. Proceeding of Annual International Research Conference on MeBr Alternatives and Emission Reductions, San Diego, CA, Nov. 8–10, 2015. p.3(1-3). Interpretive Summary: There are a number of challenges in using alternative fumigants to methyl bromide in soil fumigation for replanting of perennial crops. Reducing emissions and improving pest control especially on nematodes are both needed to reduce environmental impact and increase fumigation efficiency. This research evaluated the effects of surface sealing including a totally impermeable film (TIF) with different application rates of Telone C-35 in comparison with standard polyethylene film on fumigant emissions, distribution in soil, pest control, and almond tree response after replanting. The TIF is confirmed to significantly reduce emissions. All application rates at or above 66% of full rate provided 100% nematode control in soil above 3 ft soil depth although survival below 3 ft was observed in all treatments. Significantly better tree growth and higher yield were also obtained from all 100% and 66% rates. This research has demonstrated the high potential to reduce fumigant rate from the current maximum to 66% in orchard fumigation without compromising efficacy or yield and using similar tarps as TIF to effectively control emissions. Technical Abstract: Many growers use soil fumigation to control plant-parasitic nematodes or diseases for successful orchard replanting. However, both high emission and poor efficacy with alternative fumigants to methyl bromide need to be addressed simultaneously. The objective of this research was to test if a commercially named totally impermeable film (TIF) can help achieve good fumigation efficacy, low emissions, and a reduction in rate of application. A trial was conducted in Merced County, CA, USA from Nov. 29, 2012 through Jan. 12, 2013. Treatments included three surface sealing methods [bare, standard polyethylene (PE) film, and TIF] and four application rates [100% (maximum rate), 66%, 33%, and 0 (non-fumigated controls) rates] of Telone C-35, which was applied through shank injection at 18-inch depth. Measurements included fumigant emissions, changes in fumigant concentration under tarp, distribution in soil, efficacy on nematodes and pathogens, and tree growth and yield after replanting. The TIF was confirmed to yield the lowest emissions and also much lower off-tarp emissions compared to shallow injections for annual crops. Telone C-35 at 100% and 66% rates under both PE and TIF provided 100% nematode control at all soil depths above 3 ft, but significant nematode survival was detected in depths below 3 feet from all treatments regardless of tarp. At 33% rate, more nematodes survived in soil profile. With no significant differences among all fumigated treatments, 100% and 66% rates improved tree growth significantly from non-fumigated controls based on two years' monitoring. The first yield data collected in 2015 showed significantly higher yield from all 100% and 66% rates compared to all non-fumigated controls with some improvement at 33% rates. Ongoing research will determine whether survival of nematodes in deeper soil will affect tree performance in the long-term. The results indicate the potential to reduce fumigant rate to 66% from the current maximum without compromising nematode efficacy or yield and tarps similar to TIF to significantly reduce emissions. |