Location: Horticultural Crops Research2011 Annual Report
1a. Objectives (from AD-416)
1. Develop use-patterns for quinclorac in blackberries that maximize control of bindweed and Canada thistle, and minimize risk of crop injury. 2. Evaluate establishment potential of the gall forming mite Aceria malherbae in W. Oregon berry fields on bindweed and determine efficacy of this mite, particularly when used in combination with the herbicide quinclorac.
1b. Approach (from AD-416)
Test sites will be chosen from western Oregon berry fields where bindweed and Canada thistle is present. The most probable site under consideration is currently in EY production in the Dayton area. Quinclorac will be applied in the spring of the production year after the weeds have reached an appropriate size or just before the PHI for this herbicide (40 days), whichever comes first. Fall treatments will be applied to bindweed after the primocanes have been trained onto the wires, but just before or near the first frost. Mites will be released in two blackberry fields infested with bindweed in cooperation with the Oregon Department of Ag. Bindweed plants infested with mites will be collected, taken to the test sites and entangled with resident bindweed shoots as they emerge from the soil and are actively growing in the spring, but before flowering. Mite survival and dissemination from the point of introduction will be monitored by examining bindweed plants monthly for two growing seasons for presence of the mites and plant damage.
3. Progress Report
This interim report highlights progress made with control of field bindweed (Convolvulus arvensis) in small fruit acreage throughout the Willamette Valley. The herbicide quinclorac was applied 30 days before harvest, after harvest, and near the first frost in the fall to both EY and AY blackberries, raspberries, and blackberry and raspberry transplants. Quinclorac provided 80 to 90% control of bindweed and did not harm caneberries. A biological control agent, Aceria malherbae, was successfully established at three field sites, and caused galling of leaf tissue at all locations. In an experiment with potted bindweed plants, we found that pots receiving the high level of irrigation were colonized more by A. malherbae. Pots inoculated with mites in Year 1 had greater root mass in Year 2 compared to un-inoculated pots, in contrast to our expectations that mites feeding on bindweed would reduce root growth. Quinclorac applications reduced bindweed growth by 60% nearly one year later. Methods of project monitoring included meetings, e-mail, and phone calls.