Growing apples organically
This apple tree probably looks like it has a horrible case of powdery mildew. I’m happy to report it doesn’t! What you’re seeing are leaves that have been sprayed with kaolin clay. My husband, Bill, and I have been growing apples organically for several years now, and this is one of the tools in our arsenal to keep the dreaded apple codling moth from laying eggs on the leaves and developing apples.
The kaolin spray is believed to confuse the moths into thinking they can’t possibly be sitting on an actual leaf or apple due to the texture the spray gives them, so they don’t lay eggs. It also makes it difficult the minute codling moth larvae to crawl around on the tree to get to an apple.
The moths begin to appear shortly after the apple blossoms drop and the fruit begins to form.
A few weeks ago, he placed some codling moth traps in our small orchard as a method to determine when the moths are active in the area. The traps are sticky and, while they aren’t used to control the moths, it does trap some of them, which lets Bill know when to start spraying the apples and leaves with kaolin clay. We have to reapply it after rainstorms.
Unfortunately, we’ve learned through experimentation that you can’t use just the kaolin spray alone. Once the apples are the size of marbles, we’ll cover them with individual nylon “footies” (marketed as apple maggot barriers) to help the kaolin clay stick to the apples and last longer. Yes, it’s very tedious, especially since we usually cover about 600 apples each spring (ugh) but we team up on it and can get it done in about 3 hours. We feel it’s worth it so we can avoid using harmful chemicals. (Refer to the bottom of this post for links to sources for the products I’ve mentioned.)
Bill also uses two other organic sprays, Bt (Bacillus thuringiensis) and Spinosad. Each are deadly to the larval (worm) stage of apple codling moths, but are safe for humans. These sprays are only effective before the larvae get into the apples. He alternates between the two sprays yearly, to avoid creating a population that is resistant to either of them.
I’ll keep you posted on how the fruits are doing throughout the season. Growing apples organically can be a challenge but it’s well worth the effort!
- Kaolin clay is commonly sold under the trade name of Surround. We have found it at Wilbur-Ellis in Spokane Valley and online at Gardens Alive!
- Codling moth traps: Available at large, well-stocked garden centers such as Northwest Seed & Pet in Spokane, and online at sources like Gardens Alive! and Peaceful Valley Farm Supply.
- Nylon apple maggot barriers (a.k.a., “footies”): Peaceful Valley Farm Supply, Seattle Tree Fruit Society, and Maggot Barriers.
- Bt (Bacillus thuringiensis) can be found at garden centers such as Northwest Seed & Pet in Spokane, home centers, or online at many places like Peaceful Valley Farm Supply and Gardens Alive!
- Sprays containing Spinosad include Captain Jack’s Dead Bug Brew, which can be found at Northwest Seed & Pet, in home centers, and online such as Gardens Alive!