Agronomic Minute: Getting Ahead of Walnut Blight

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Walnut blight is one of the many problematic issues that growers face from year to year. In making plans for the coming season, growers will want to keep in mind the most effective approach for mitigating any potential damage. Technical Service Lead for Specialty Crops for UPL, Joe Vassios said that after lower levels of infection last year, growers may not be as diligent in their preparations. However, staying in front of any infection will be the most effective approach in keeping orchards clean.

Weed Pressures

“Last season, with the hot dry conditions that we had here in California, walnut blight pressure was lower than it can be in many years. So, I think that fewer applications probably went out last season or were needed for walnut blight,” said Vassios. “But with some of these early rains that we’ve had this fall, if this trend continues, you really want to make sure that you have a solid plan in place for managing that walnut blight to protect your trees and protect your yield going into this next season.”

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. Any rainstorms that come through will then disperse the bacterium to other sites in the orchard, spreading the potential for infection. Getting ahead with application programs will help to stay in front of any potential infections.

“More traditional application programs for managing walnut blight would include a mancozeb, or UPL’s Manzate Pro-Stick, in combination with a copper-based product such as UPL’s Cuprofix. That’s been effective for many, many years,” Vassios 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.