Location: Horticultural Crops Research2012 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:
The objectives of this project were to determine: 1) whether the herbicide quinclorac can be used to control or suppress bindweed in blackberries without impacting crop performance; and 2) whether a biological control of bindweed, the gall-forming mite Aceria malherbae, can be established in berry fields and used in concert with herbicides to enhance bindweed control. 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. The bindweed mite Aceria malherbae was collected from sites in central OR and near Prosser, WA and applied to growing bindweed in 2009 through 2011. The mites established and overwintered at several field sites but did not have a significant impact on bindweed growth, even when used in concert with quinclorac. In two studies where bindweed was confined to pots, quinclorac greatly reduced shoot and root biomass. The effect of the bindweed mites in confined pots was dependent on irrigation level. This research was conducted in support of objective 3A: Sequence viruses associated with bluberry necrotic ringblotch and blueberry mosaic diseases for use in the development of diagnostic tools of the parent project.