Location: Crop Improvement and Protection Research
2022 Annual Report
Objectives
Objective 1: Conduct laboratory and field tests to provide residue data needed to establish a tolerance on a specific commodity or to support a crop group tolerance.
Approach
Research to support registrations of minor use pesticides. Apply pesticides according to IR-4 protocol guidelines. Obtain performance data, phytotoxicity, yield, and efficacy from treated and untreated field plots. Ship samples to laboratories for residue analyses. Protocols will be employed using appropriate Standard Operating Procedures and conducted under provisions outlined in 40CFR part 160 in accordance with EPA's Laboratory Practice Standards.
Progress Report
This report documents progress for project 0500-00007-121-00D, which started in October 2020, "Minor Use Pesticide Testing on Vegetables and Sugar Crops." Interregional Research Project #4 (IR-4) field trials were conducted on projects during FY22 according to approved protocols developed by IR-4 Project Headquarters. Following local recommended practices for agricultural production, field testing was done on vegetables and herbs. Commercially acceptable minor crops were grown and sprayed according to the protocols with test substances using small plot sprayers that simulate commercial application equipment. Various pesticides were evaluated in the field test plots on several minor crops. Plants were monitored frequently for phytotoxicity from application treatments and timing of sprays. Residue samples were collected at harvest time and stored frozen until shipment to a designated IR-4 analytical laboratory for residue analysis. Field data was submitted to IR-4 Headquarters.
Five projects were conducted on fresh market tomatoes, both small and large fruit, for disease and weed control. The fungicide pyraziflumid was applied in three field trials for control of southern blight (Sclerotium rolfsii) and the applications were made by drench or drip methods. Two field trials, using a herbicide combination of flumioxazin and pyroxasulfone, were conducted on tomatoes. The herbicide was applied in a band near the base of the plants and the plots were monitored for weed control, including common purslane, pigweed and sedges, which are commonly found in tomato production.
The fungicide combination of difenoconazole and azoxystrobin was sprayed on spinach to control the foliar disease Stemphyllium. Four foliar sprays were made to the spinach at seven day intervals with the samples harvested at one day after the last application. Azoxystrobin is currently registered for spinach but difenoconazole is not labeled for use on spinach.
Two carrot projects, in cooperation with Agriculture and Agri-Food Canada, were undertaken to establish a maximum residue limit tolerance from the fungicide combination of oxathiapiprolin and mandipropamid. This material was applied in four broadcast foliar applications at seven day intervals with a seven day pre-harvest interval (PHI). One of these trials was a decline study to determine how the fungicide breaks down over time. Carrot samples were collected at one, three, seven, ten and fourteen day intervals.
Another field trial was conducted on basil to control downy mildew using the fungicide fluoxapiprolin. Three foliar sprays were made to the basil at seven day intervals with a zero day pre-harvest interval (PHI). Fresh and dried samples were collected.
One assigned trial was established to evaluate methods for control of winter annual and biennial weeds in commercial stevia production. The trial was over wintered in the field and sprayed when the plants were dormant during the winter with the herbicide linuron. There was no observed phytotoxicity from the two applications. When the stevia plants are commercially mature, they will be harvested for fresh and dried samples.
Eleven field trials are in progress or partially completed on cool season vegetables and strawberries. The vegetable work is being done on carrots, turnips, radishes, lettuce and squash crops. Three projects on annual strawberries involve disease and weed control studies.
Accomplishments
1. Minor use pesticide residue tests. Ten field trials were conducted by ARS researchers in Salinas, California, on minor crops, vegetables and herbs, with various fungicides and herbicides. Fresh market tomatoes represented five projects using a fungicide to control southern blight and a herbicide for weed control. One trial was conducted on spinach for control of the foliar disease Stemphyllium. In cooperation with Agriculture and Agri-Food Canada, two carrot trials were completed to establish a maximum residue limit tolerance for the fungicide combination of oxathiapiprolin and mandipropamid. One field trial was conducted on basil with the fungicide fluoxapiprolin to control downy mildew and fresh and dried samples were collected. ARS researchers will continue to assist specialty crop growers by participating in IR-4 sponsored field research projects.
