The overall goal of this project is to develop best management practices (BMPs) to minimize the risk of pathogen infection and reduce pesticides use in vegetable transplant houses in California. Over the last 20 years, processing tomato production in California has shifted from planting fields with seed to planting with transplants; with the consistent yield gains, all growers now use transplants. Other vegetable industries such as market tomatoes, melons, peppers, among others are following suit, to gain similar yield benefit. This has led to the emergence of a new vegetable transplant nursery sector in California with significant pest management needs and challenges. As a recent type of production system, vegetable transplants do not have specific best management practices (BMPs) available for disease control, relying almost exclusively on chemicals to attempt disease control, often unsuccessfully. As pre-existing methods developed for woody food crops or ornamentals nursery crops do not necessary extrapolate with transplant production.In response to growers and farm advisors need to have a better understanding of diseases affecting vegetable transplant crops, recent surveys at three cooperating greenhouses in the Central Valley indicated that losses are being driven by several diseases including Botrytis leaf blight (B. cinerea), black root rot (Thielaviopsis basicola)and Pythium root rot (Pythium spp.). To develop better cultural strategies, that not solely rely on chemical treatments, it is important to understand how pathogens are moving within production houses, and which steps of production are facilitating infection. A Hazard Analysis of Critical Control Points (HACCP) can be used to identify which stages of production harbor pathogens and can promote disease development. In response to request from vegetable-seedling growers in California we propose to:1. Conduct site-specific Hazard Analysis of Critical Control Points (HACCP) with collaborating greenhouses2. Develop culture practices to reduce pathogen spread and infection at critical control points, and conduct validation studies (at commercial cooperating facilities) to determine efficacy in controlling diseases3. Screen new chemicals and biological fungicides for efficacy in managing pathogens4. Disseminate new management recommendations through grower meetings, workshops, newsletter articles.