A Battle for Healthy Pistachios: New Chemistry Helps Combat Late Blight

Taking on Late Blight
Luna Sensation and Luna Experience fight resistant disease in California pistachio orchards

Luna Sensation and Luna Experience fight resistant disease in California pistachio orchards
Pistachios have one of the highest acreages for nuts produced in the United States, and production is on the rise. In the past few decades, the pistachio sector in California has seen steady expansion, increasing dramatically from 1,700 bearing acres in 1977 to 178,000 in 2012, as recorded by surveys from the U.S. Department of Agriculture.

Along with the steady increase of pistachio production, consumer demand for pistachios is also growing. Pistachios have been promoted as a healthy and convenient snack, reinforcing consumption habits across the United States and worldwide.

A threat to California pistachios

California plays the principal role in the nation’s pistachio sector, producing roughly 98 percent of the country’s pistachios. However, the pistachio crop in California has a high level of genetic uniformity, making them vulnerable to disease threats and resistance issues.

One of the most severe threats is late blight in pistachios. Damage to orchards from Alternaria late blight stems from any of three different species of Alternaria, often causing early defoliation of trees and nutshell staining. In recent years, the disease has become more difficult to manage, as fungicide resistance issues have been reported.

One of the most severe threats is late blight in pistachios

Alternaria late blight and fungicide resistance

Themis Michailides, a researcher at the University of California, Davis, has been conducting research on pistachios for more than 25 years and was one of the first to identify the growing pistachio fungicide resistance issue for Alternaria late blight. Through his research, Michailides has reported a decrease in efficacy for strobilurin fungicides and mixtures of carboxamide with strobilurin fungicides.

“Alternaria blight has been so severe and difficult to control that fungicide resistance issues are a major concern,” said Michailides. “In checking Alternaria isolates for resistance, we found that most of the isolates that were resistant to boscalid chemistries were cross resistant to penthiopyrad chemistries.”

Alteria blight

Luna fungicide: an effective new chemistry

But as different chemistries are introduced into the market, there is hope for a resolution to current resistance problems, researchers said. For example, fluopyram, the active ingredient in Luna® fungicide from Crop Science (including Luna Experience and Luna Sensation), offers growers a new chemistry to combat Alternaria concerns. Although fluopyram shares the same mode of action as the carboxamide chemistries, it differs significantly in shape and molecular flexibility from these other fungicides.

Michailides conducted tests on fluopyram to determine the new solution’s efficacy in comparison to fungicides for pistachios containing other carboxmide chemistries. His studies on Alternaria isolates demonstrated no current cross-resistance for fluopyram.

“Fluopyram has a different structure than boscalid and penthiopyrad, offering a new chemistry for growers to use in managing Alternaria,” said Michailides. “In our experiments, Luna performed exceptionally well and in some cases a little better than the other fungicides in controlling Alternaria.”
In our experiments, Luna performed exceptionally well and in some cases a little better than the other fungicides in controlling Alternaria

Efficacy against multiple diseases

Along with its effective performance in Alternaria efficacy trials, Michailides said he is also hopeful for the product’s impact on the prevention of botryosphaeria and botrytis infections in pistachio. Through laboratory trials, Michailides found high sensitivity of botrytis to the product with zero infections and complete prevention of the disease.

“Our research points to Luna as an excellent material for all the major diseases of pistachio in California,” said Michailides. “Based on our resistance studies, I would definitely expect for its efficacy to last longer than other analogous fungicide mixtures.”

California’s pistachio production plays a critical role in the nation’s tree nut sector. With the resistance to certain pistachio fungicides containing carboxamide chemistries on the rise for damaging diseases, crop protection experts say it is critical for pistachio growers to utilize products suited for resistance management by alternating fungicide chemistries.

Works Cited

AgAlert, April 2013.

View all labels / MSDS

Find unique answers to major crop threats for greater success in the field. » more
Sign up to receive alerts about Crop Science products and promotions. » more
Copyright © Bayer CropScience