With harvest wrapped up and data collected from the Fresno, CA, Grow More^TM Experience site, we can take a look at the 2019 season and see how we can better prepare for grapes and citrus disease pressure in 2020.

If there’s one critical takeaway from 2019’s trials, it’s to heavily scout orchards and vineyards. Looking at past trends, we may not see much rainfall this year, which will increase uses of lower-quality well water and add drought stress. This makes crops more susceptible to disease and pest pressure, as their natural defenses are compromised.

Citrus growers should prepare to defend orchards against Phytophthora, a common pathogen found in CA soils. This disease thrives in cool, wet conditions, and growers will want to look closely for damage, as the impacts of this pathogen are commonly mistaken for water stress and nutrient deficiency.

Because strong, healthy root systems are essential to overall citrus tree health and productivity, it’s important that growers establish an aggressive ongoing management plan for Phytophthora. Control is important, and treatment can drastically reduce inoculum levels when a good program is followed.

Rotating sites of action are essential to managing for resistance. Ridomil Gold® SL and Orondis® fungicides are high-efficacy rotation partners, and can help protect against root rot and improve root health.

Grape growers, meanwhile, will want to scout for powdery mildew in 2020. Typically spotted around early to mid-season, it’s identified by its powdery or dusty appearance on the surface of fruit and leaves. Powdery mildew can delay fruit maturity and reduce efficacy and overall yield. One infection can take out entire clusters and rows of grapes.

The best way to prevent a powdery mildew outbreak is to apply a fungicide like Inspire Super® before the disease is identifiable in vineyards.

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