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United States Department of Agriculture

Agricultural Research Service

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Location: Crops Pathology and Genetics Research

2013 Annual Report

1a.Objectives (from AD-416):
Objectives are as follows: 1)Evaluate the impact of microbial inoculants on the incidence and severity of soilborne disease and on the overall health and vigor of bedding plants; 2)Evaluate the effect of adding pheromones to sticky traps on ability to monitor/detect thrips populations and for the potential to reduce thrips populations and the resultant damage on a variety of ornamental crops; 3)Evaluate the addition of silicon to ornamental crops to reduce damage by insects and mites and to produce healthier and more vigorous plants; and 4)Transfer effective new technologies to appropriate customer/stakeholder groups.

1b.Approach (from AD-416):
1) Through a series of research/demonstrations, will evaluate the relative performance of a variety of microbial inoculants compared to normal grower practices; 2)in cooperation with growers in California, will evaluate the use of pheromone/sticky traps on control of thrips in a commercial greenhouse; 3)in cooperation with growers, will run side by side comparisons of plants grown with and without the addition of silicon to determine if adding silicon to ornamental plants will increase their ability to resist attack insects and diseases and produce healthier and more vigorous plants; and 4)will develop a Bedding Plant/Plant Propagators Alliance. Via meetings of this Alliance, will complete a Crop Profile for bedding plant producers and plant propagators.

3.Progress Report:

This agreement was established in FY08 as a Specific Cooperative Agreement associated with Food and Nutrition Research Institute (FNRI) research; the goal being to develop and implement Integrated Pest Management (IPM) for bedding plants. The goal of this project is to evaluate the impact of microbial inoculants on the incidence and severity of soilborne disease and on the overall health and vigor of bedding plants. This is the final report for this project.

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 -.
1)the addition of silicon and/or AG 1000 (a microbial inoculant),.
2)a scouting program to monitor key pests,.
3)the use of biological control agents (primarily predatory mites, entomopathogenic nematodes, and entomopathogenic fungi, and.
4)the use of reduced risk biopesticides whenever possible.

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: 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).

Last Modified: 8/22/2014
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