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- Rancho Cucamonga, CA
Am I supposed to spray something on my apple tree so it doesn’t get that dust mold and ruin every apple the tree grows?
- Oakland, OR
It sounds like your apples have a case of powdery mildew, a fungi that flourishes in warm dry climates. Some apple varieties are more susceptible than others, but you can up their odds against getting the mildew by providing good air circulation via pruning and avoid over-fertilizing with nitrogen. The disease can attach from the pre-bloom stage through fruit set.
The good news is there are many environmentally-safe ways to thwart the disease. You can spray with a lime-sulfur as a dormant spray (in winter when trees are dormant), or with a lime-sulfur or sulfur spray when you first see symptoms. Another study-based option is to spray the trees with milk; combine one part room temperature skim milk with nine parts water and spray. If you have a sprayer that attaches to the end of your hose, then fill the container half to full with skim milk and it will dilute as water goes through. Last line of attack is to spray with liquid seaweed, then spray with solution of one teaspoon baking soda to 1 quart of water--the baking soda spray creates an inhospitable environment for the mildew. It’s best to spray at 7 to 10 day intervals until the mildew is gone. Good luck!