Location: Emerging Pests and Pathogens Research
Project Number: 8062-22000-020-10-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Sep 1, 2018
End Date: Aug 31, 2020
New Technologies that Manage Profit-Limiting Diseases with a Focus on Botrytis. The production of top quality floral crops is the goal of this proposed research. Further, we propose to limit management costs by incorporating new technologies and strategies to protect valuable floricultural crops from disease. Greenhouse floral crops are at risk from foliar and root rot diseases causing poor plant quality, plant death, and increased production costs. Botrytis cinerea is identified as a major problem during production, shipping and postharvest, causing leaf spots, blighting, stem cankers and damping off. Controlling Botrytis is difficult because it can infect crops at almost any stage of growth and damage all plant parts. Botrytis has adapted to some fungicides rendering them ineffective, but the extent of this problem is not known. Downy mildews have re-emerged on some greenhouse crops causing defoliation and plant stunting on susceptible crops including impatiens. Root rot results from different soil-inhabiting pathogens and can move among producers and greenhouses via plants and recirculated irrigation water. Fungicide resistance affects recommendations and control success and available biocontrols may offer relief. Reduced risk fungicides and biopesticides with novel/unique modes of action are particularly needed for rotation schemes designed to manage and delay resistance and reduce the release of harsh pesticides into the consumer’s environment. The overall objective of this cooperative research project is to develop new technologies and strategies to manage costly diseases of greenhouse floriculture crops with a focus on Botrytis. Specific activities include: 1) Determine cultivar susceptibility to Botrytis, 2) Test biological and conventional products against Botrytis; 3) Collect Botrytis isolates from infected plants in greenhouses representing different crops and test for resistance to the fungicides commonly recommended for protection; 4) Determine which fungicides can protect susceptible plants during propagation, shipping, and postharvest; 5) Identify effective new fungicides and protection programs that include different modes of action for impatiens downy mildew for application in the greenhouse and determine longevity of protection in the landscape; 6) Test new plant-protection products, including reduced-risk fungicides, biopesticides, and biocontrols against root rot (e.g. Thielaviopsis basicola, Phytophthora spp., and Pythium spp.) and foliar spots and blights (e.g. downy mildew, powdery mildew); and 7) Provide results and recommendations directly to producers and allied industries via publication in trade magazines, website updates, and presentations. YouTube videos and other novel approaches to communicate the highlights of this work broadly will be used to complement the more traditional extension activities.
Our project objective will be accomplished through a research team including experienced research and technical specialists, a post-doc, a graduate student, and undergraduate students who will work together to pursue and complete activities within the framework of proven and robust plant pathology research and testing protocols through cooperation and collaboration with greenhouse growers and other floriculture researchers throughout the United States. Activities 1 through 4 will focus on Botrytis disease solutions. Each activity will be conducted under controlled environmental conditions in either a research greenhouse or growth chambers. Test plants will be inoculated with a Botrytis pathogen verified to be capable of causing disease at a dosage that results in an optimal level of disease based on our previous studies. Each treatment will include a minimum of four replicate plants along with the appropriate controls. Plant protection products will be applied according to the registrant’s instructions (drench or spray) and reapplied throughout each study at the specified intervals. We will screen cultivars of petunias, geraniums, and two additional floricultural crops (to be identified by our collaborating growers) for Botrytis susceptibility. Production scenarios where Botrytis is especially difficult to manage including propagation, post-harvest, and shipping will be the framework within which the plant-protection products will be tested and evaluated for efficacy. Disease assessments will be made according to published protocols with statistics applied to discern treatment difference. To test for fungicide resistance, a minimum of 100 Botrytis isolates will be collected and cultured from diverse greenhouse crops (at least five) on agar media, transferred for a pure culture, and placed into long-term storage until tested. Each isolate will be tested for fungicide resistance using ‘poison plates’ and verified with fungicide-treated plants that will be inoculated. Fungicides will include older standards (e.g. iprodione, fenhexamid, and chlorothalonil) and newly-registered fungicides. Activities 5 and 6 will focus on solutions to other significant disease threats to floricultural crops. Efficacy trials for downy mildew products applied to impatiens in the greenhouse will be evaluated in infested landscape sites for longevity of disease control. Treatments will include single active ingredients and programs including tank-mixes that combine and alternate modes of action. Phytophthora, Pythium, Rhizoctonia, Thielaviopsis and powdery mildew will be retrieved from our long-term storage and used to inoculate susceptible plants in individual trials. These replicated and controlled studies will include reduced risk fungicides and biopesticides. Data to be collected will include plant quality, health, and size. Application rates and intervals will be defined and tested to determine consistent and reliable control. Activity 7 will ensure that results and recommendations are disseminated to agricultural extension scientists, commercial growers, product manufacturers, and allied industries via presentations and publications.