Location: Water Management ResearchTitle: Emission and crop response in almond orchards fumigated with reduced rates of Telone® C-35 and low permeability film for nematode control Author
|Doll, David - University Of California - Cooperative Extension Service|
|Qin, Ruijin - University Of California|
|Rana Dangi, Sadikshya|
|Hanson, B - University Of California|
Submitted to: Crop Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/17/2017
Publication Date: 12/5/2017
Citation: Gao, S., Doll, D.A., Qin, R., Rana Dangi, S., Gerik, J.S., Wang, D., Hanson, B.D. 2017. Emission and crop response in almond orchards fumigated with reduced rates of Telone® C-35 and low permeability film for nematode control. Crop Protection. 105:80-89. https://doi.org/10.1016/j.cropro.2017.11.010.
DOI: https://doi.org/10.1016/j.cropro.2017.11.010 Interpretive Summary: Many specialty orchard crops rely on pre-plant soil fumigation to control soil-borne pests, and adequate pest control is required for successful fumigation with alternative fumigants to methyl bromide. This research investigated the application of a totally impermeable film for reducing fumigant emissions, reducing fumigant rates, and improving tree performance after fumigation and replanting. Results confirmed that the impermeable film was effective in reducing emissions, and the 66% rate provided similar pest control as the full rate. The 66% rate also resulted in similar yield as the full rate, indicating that the reduced fumigant rate can be used without compromising yield. This research also identified the challenge for delivering fumigants to deeper soil depths for improved fumigation efficiency.
Technical Abstract: Many high value tree crops are dependent on soil fumigation for control of plant-parasitic nematodes and diseases for successful orchard replanting. Due to detrimental impacts on the environment, fumigants are under stringent regulations. The objective of this study was to test if a commercially available totally impermeable film (TIF, VaporSafe™) can help growers use reduced fumigant rates to achieve emission reduction and effective control of soil-borne pests. A field trial was conducted in a commercial almond orchard in the San Joaquin Valley of California, USA. Treatments included an unfumigated control, full (100%) and reduced (33% or 66%) rates of Telone® C-35 (a mixture of 1,3-dichloropropene and chloropicrin) applied through shank injection to 46 cm soil depth in tree rows, and three surface sealing methods (bare, standard polyethylene film, and TIF]. Treatment effects on fumigant movement, nematode and pathogen survival, and tree performance after replanting were determined. The TIF was proven to reduce emissions most effectively and also resulted in much lower off the edge emissions compared to when fumigants were applied to a shallow depth (30 cm). Both 100% and 66% rates, regardless of surface sealing methods, promoted tree growth with no significant difference in almond yield during three years of monitoring. The 66% rate under films regardless of film type also provided similar nematode control as the full rate. However, none of the treatments provided adequate control of nematodes at soil depth 120–150 cm. All data suggest a challenge in delivering the fumigants to deep soil and a need for further improvement of fumigation efficiency in orchard replant settings.