2012 Annual Report
The large-plot fumigant demonstration plots established near Wasco, CA, and Yuba City, CA, in FY2010 were terminated in early FY2011. These commercial scale demonstration plots (0.6 ha each) were primarily used for extension and demonstrated that alternatives to MB can lead to good performance of nursery crops if soil conditions allow. For the emissions work, another trial was conducted in cooperation with UC and ARS researchers near Parlier, CA, to evaluate pest control and fumigant emissions from reduced rate applications of MB alternatives applied with high barrier film. This experiment brought together various scientific disciplines to evaluate emissions as well as weed, pathogen, and nematode control with 1,3-dichloropropene and chloropicrin rates as low as 25% of normal use rates under standard polyethylene film compared to totally impermeable film (TIF).
Six herbicide screening trials were conducted in FY2011 in commercial almond nurseries near Oakdale (1), Yuba City (2), and Newcastle (2) to evaluate the performance and nursery stock safety of various herbicides including isoxaben, rimsulfuron, dithiopyr, penoxsulam, indaziflam, sulfosulfuron, and foramsulfuron. The extension component of his work has increased grower confidence with some registered herbicides and identified other, currently unregistered materials that should be considered by the manufacture for future registration. To date, crop safety has usually been adequate with oryzalin, pendimethalin, and isoxaben, all of which are labeled for use in tree nurseries. Dithiopyr, rimsulfuron, oxyfluorfen, foramsulfuron, and lower rates of indaziflam and penoxsulam applied preemergence and post-directed can provide good to excellent weed control in some fruit and nut tree rootstock. However, because slight crop injury was occasionally observed additional work on application rates, timing, and method of application especially on non-labeled herbicides is needed before these materials can be safely applied to newly planted rootstock on a broader scale.
During the review period, information from this project and related research was disseminated through scientific and extension channels. Scientific reports included a nursery fumigation paper published in Pest Management Science (Jhala et al. 2011), a nursery herbicide paper submitted to Hort Science (Abit and Hanson), and a five-year overview of nursery fumigation research submitted to California Agriculture (Hanson et al.). Additionally, five extension presentations and a field day tour on fumigant issues or nursery herbicides were made to stakeholders during the performance period. Finally, the information generated in this nursery project was used during the development of a template for a multi-state, multi-investigator outreach website tying back to the goals of the Pacific Area-Wide Program for Integrated Methyl Bromide Alternatives.