What is in this article?:
- Scab, rust increasing with almond orchard humidity
- Spray timing
- Resistance management
- If leaves are falling prematurely in late summer or early fall, chances are it is due to two diseases, scab and rust.
- Foliar diseases are becoming more problematic in California almond orchards.
- If scab has evolved into a serious problem, a delayed dormant application of copper and oil is now recommended.
There is a wide array of fungicides available for disease control. However, there is the ever-present threat of resistance from overuse or misuse.
Doll believes this concern is being heightened by the marketing of pre-mixed products with different active ingredients in the mix.
“They are great fungicides mixed together, but my concern is how to manage resistance with these pre-mixes,” according to Doll. “It is not effective resistance management if you follow one of these pre-mixes with the same active ingredient as one of the two products in the tank mix.
“Following a strobilurin and DMI tank mix with a single mode of action strobilurin or DMI is not good resistance management.”
He recommends following a pre-mix with sulfur, copper, sulfur or chlorothalonil.
“I do not blame farmers for using these pre-mix products, but I would highly recommend they rotate with something completely different,” he added.