Environment

In the Spring 2026 issue of the UCNFA Newsletter, the first Featured Article highlights the irrigation education priorities for nursery employees that were identified by focus groups of California nursery managers. In our second Featured Article, a summary of California’s floriculture and foliage industry from the USDA 2022 Census of Agriculture is presented. In Science to the Grower, researchers from Cal Poly SLO describe how monitoring fungicide effectiveness can help control powdery mildew in Brassica seedling production.

As water scarcity and state regulations challenge California’s horticultural industry, many nurseries are turning to recycled runoff water as a primary or supplemental water source. While a “no-discharge” reality presents logistical hurdles, it also offers an opportunity to improve resource efficiency, however careful management must be taken not to spread chemical and biological contaminants throughout your property and into neighboring properties. 

Cottonseed bug (Oxycarenus hyalinipennis) is an invasive pest that was first detected in Los Angeles County in 2019 and has since spread across most of Southern California. It can now be found in San Diego, Orange, Riverside, Los Angeles, Santa Barbara, and San Bernadino Counties. Cottonseed bug (abbreviated CSB) primarily feeds and reproduces on malvaceous hosts like cotton, hibiscus, and mallows, but can also be found feeding on a wide variety of other plants from wheat to citrus. CSB feeding can cause seeds to abort and will occasionally damage fruit or young shoots.

In this Fall 2025 issue of the UCNFA Newsletter, our Featured Article discusses current ongoing research evaluating the pathogen risks of irrigation with untreated recycled irrigation water on ornamental crops in San Diego County, including preliminary findings and potential grower implications. In Science to the Grower, we introduce an improved metric for measuring greenhouse light levels, Photosynthetic Photon Flux Density, to more accurately adjust lighting for optimal crop production.

Water scarcity continues to challenge California’s floriculture industry, leading many nurseries to rely on recycled irrigation water as a supplemental or primary water source. Although this approach conserves water, it also increases the risk of recirculating plant pathogens, particularly oomycetes such as Phytophthora, Pythium, and Phytopythium. These organisms move easily in water and can initiate new disease cycles each time crops are irrigated.

In this Summer 2025 issue of the UCNFA Newsletter, our Featured Articles focus on diseases on nursery crops, presenting the most recent diagnostics data from ornamental nurseries in California out of the Greenhouse and Nursery Pathology Lab at UC Davis. We will also discuss the impact and biology of powdery mildew in California nurseries, including practical guidelines for identification and management.

Phytophthora diseases are a growing concern to restoration and nursery plant production that have led to huge economic and ecological losses. Here in California, most people may know of Phytophthora (lit. “plant destroyer”) from the devastating outbreak of Sudden Oak Death, caused by the aerial Phytophthora ramorum, in the 1990s – 2000s in Northern California and Southern Oregon.