Agronomic Minute: Keeping Walnut Blight Top of Mind

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Growers that have been dealing with walnut blight will want to make sure and be proactive with their preventative measures. Technical Services Manager for UPL North America, Katie Driver said that growers will be best served by keeping the issue in mind as they make plans for the season ahead. While blight pressure has not been overly severe in the past few years, growers will want to be prepared in the event of increased rainfall in the coming season.

Walnut Blight

“Growers that may be dealing with a history of walnut blight in their orchards are likely well-versed in making preparations to combat any damage. The pathogen that causes walnut blight can overwinter in between scales,” Driver explained. “Any rainstorms that come through will disperse the bacterium to other sites in the orchard, spreading the potential for infection. So, getting ahead with application programs will help to stay in front of any potential infection.”

University of California Integrated Pest Management guidelines note that protective sprays are an essential aspect of management. Infection can depend on environmental conditions, the amount of inoculum in an orchard, and the number of cankers that are present. Driver said that growers will want to order the materials they need early to ensure availability when the time comes to make applications. There are a variety of materials available to growers to help protect orchards from walnut blight damage.

“More traditional application programs for managing walnut blight would include a mancozeb, or UPL’s Manzate Pro-Stick, in combination with any copper-based product such as UPL’s Cuprofix. That’s been effective for many, many years,” Driver noted. “More recently, there have been some areas where copper resistance has been identified. While it’s not widespread yet UPL does offer our Kasumin product, which is a kasugamycin-based product that can provide great control where that copper resistance is appearing.”

Listen to the full episode below.