2013 Annual Report
This past year we have focused on working with cooperating growers in several locations in California in addition to conducting lab/greenhouse trials on the University of California (UC), Davis, campus to reinforce the field work. The overall idea was to implement an IPM program for bedding plant growers and plant propagators that would incorporate the following -.
As expected, we had mixed results across the state working with cooperating growers. This was not unexpected, since no two operations in the state are identical in how they grow plants: production practices vary enormously in terms of plants and plant cultivars grown, soil-less mixes used, the water quality and watering frequency, overall intensity of fungicide and insecticide application and the degree of greenhouse environmental management. The larger and more 'corporate' operations see the value in monitoring and they have the resources to devote to this activity. Smaller growers do not see the value. Furthermore, monitoring is really only used to tell if a pest is moving into the greenhouse or if pests are increasing/decreasing. No thresholds are utilized when making a pesticide application decision. Data are still being analyzed for both the silica and microbial inoculants, but we did find regular applications of the microbial inoculants proved beneficial in most cases. We were unable to control powdery mildew but we were able to reduce the number of applications of fungicides for control of water molds. Plant quality and root growth appeared to be superior where microbial inoculants were used and this work is ongoing. With respect to biological control, the results were somewhat disappointing, since we expected both entomopatogenic nematodes and predatory mites to work effectively against fungus gnats in most situations. These natural enemies are expensive (especially if regular applications are made) and results were mixed. We are currently conducting trials with these natural enemies on the UC Davis campus to address the possibility that intraguild predation may be occurring, and if so, does this reduce their overall effectiveness in controlling fungus gnat populations. An analysis of the economic viability of this rather simple IPM program across the different cooperating growers was far more difficult than originally anticipated. While the overall records on pesticide use are available from the California Department of Pesticide Regulation (CDPR), getting that information from specific growers was difficult. Although complete records are not available, we are doing our best to construct an economic analysis of these programs.
In my laboratory and greenhouses on the UC Davis campus, we determined the compatibility of selected microbial inoculants with both fungicides and insecticides. This was done with the idea that if growers tank mix pesticides with the microbial inoculants, there may be some mortality of the beneficial microbes. We have completed this work and there are some very interesting differences across the fungicides and insecticides. This information has already been presented at a grower meeting. We have done similar work (over time) with these microbial inoculants mixed with fertilizers.
The floriculture and nursery industy are being dramatically impacted by invasive species. To try and address this in the current project, we participated in the development of a Best Management Practices Online Tool to better enable the nursery industry to deal with invasive species. This is still in a 'beta' version and can be found at: http://ucanr.edu/sites/UCNFA/CANGC_Unified_BMPs_Project/Pests/. We are working with the glassy-winged sharpshooter (GWSS), Homalodisca vitripennis, to see if it can be impacted by the application of silica to one of its host plants, roses. We are working with a cooperating grower in Ventura county and we have a colony of GWSS in the Contained Research Facility on the UC Davis campus.
We continue to evalaute reduced risk pesticides against the major greenhouse pests including western flower thrips (Frankliniella occidentalis), two-spotted spider mites (Tetranychus urticae), the citrus mealybug (Plannococcus citri) and the serpentine leafminer (Liriomyza trifolii).