Grape growers might have a tougher time than average with powdery mildew control this year. Once the disease settles in a vineyard it can be exceptionally difficult to eradicate. Technical Services Manager for UPL North America, Cassie Rieser said control might be more challenging this year due to weather conditions.
“Wet springs that tend to saturate the ground and promote large canopy growth that definitely increases humidity levels in those microclimates in those vines. Fungal infections overwinter in both dormant buds as well as on the cordons and arms of grapevines,” Rieser explained. “So, on warm winter days or spring days with lots of moisture, those overwintering fungal sources will burst and release ascospores that will stick to newly emerged leaves.”
A heavy presence of powdery mildew can cause significant damage to plant growth. That can take a toll on crop yield as well as fruit quality. The disease can require season-long maintenance because of the early season inoculum and secondary infections that proliferate throughout the summer. Depending on the weather conditions, secondary infection cycles can happen every five to 30 days. Rieser noted that they have several options in their portfolio that can help growers protect vineyards from powdery mildew damage.
“Vacciplant is one of our preventative biofungicides that works best in tandem with your standard fungicide tank mixes. Its active ingredient is laminarin, which is an oligosaccharide or sugar molecule that actually is in its own FRAC group; so P4,” said Rieser. “The fact that it’s a unique FRAC group means it’s a great tool for resistance management. While simultaneously activating the plant’s natural defense systems, or the SAR and ISR pathways. The activation of these pathways has also led to interesting trends in improving fruit quality metrics along with powdery mildew control.”
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