Kaolin, or “China clay,” is an essential ingredient in the manufacture of fine china and porcelain. It has also been widely used in the making of paper, rubber, paint, and heat-resistant products. Fine chinaware is, of course, associated with the nation that first refined the process, and the name kaolin arises from the Chinese for Kau-ling (“high ridge”) - the designation for a hill in China where the earliest pure clay samples were obtained by a Jesuit missionary about 1700.
Bought generically from suppliers of pottery clay or as an EPA-registered product called Surround WP, this material is mixed with liquid soap and water. When sprayed on plants, it forms a mineral film that grasshoppers don't like. The white mineral film left on the leaves and fruit repels hard-to-control insect pests such as grasshoppers and should help repel birds.
Here's my recipe: Mix 1 quart of kaolin clay and 1 tablespoon of liquid soap with 2 gallons of water, or follow label directions. Spray the plants thoroughly.
- Professional Strength
- 25 lb. Bag
- Proven Effective on over 100 types of Eating Insects
- It can be applied up to day of harvest
- Easily rubbed off when the fruit or produce is ready to eat
- Surround can help control pests
Surround WP acts as a protection against insects, disease & sunburn. Derived from Kaolin clay, a natural mineral, Surround forms a barrier film that acts as a broad spectrum crop protection. It works to control insect pests and disease while protecting against sunburn and heat stress. The kaolin clay coats the plants with a white powder film that acts in several ways to deter pests. It creates a hostile environment for insects and mites, the particles adhere to the insects acting as a strong irritant and the film creates a physical barrier to insects like psylla.
The material is porous, which allows the important processes of gas exchange to occur. In addition, Surround helps prevent sunburn damage and can enhance fruit coloring. Surround is applied as a water-based slurry and needs to be applied before pests arrive. Must be mixed well before application. Sprayer with continuous agitation is recommended. Fruit needs to be washed prior to sale. Use 50 lb/acre or 1/2 lb/gallon water. Reapplication is required every 7-21 days. Use on trees such as apples, pears, peaches, citrus, berries and some field crops. May be used for Japanese beetles, leaf rollers, mites, thrips, codling moth, psylla, flea beetles, leaf hoppers, etc.
Surround proves best effectiveness once 3 uniform applications have been made. One coat of clay is simply not enough coverage to actually deter the insect's normal inclinations. Make back-to-back applications to get to this launching point of successful orchards. Coverage then needs to be maintained weekly for approximately four weeks. Heavy rain may necessitate additional applications.
Label instructions recommend a rate of 25 lbs of Surround per acre per application. Whether you mix this in 50 gallons of water or a 100 gallons of water is determined by sprayer type and the size of the trees on your acre. Coverage needs to be applied to the point of runoff and allowed to dry. A sticker-spreader isn't necessary, and in fact, experiments with vegetable oils to improve kaolin's holding power have decreased efficacy. The coverage provided by a hand-held wand spray rig is often superior to an air-blast sprayer simply because you take more time per tree to achieve a full coat.
Question: I have a grapevine in my back yard. Every year, it is loaded with grapes, but they disappear before I can get any. I guess birds must be eating them. Is there a way to protect them? There appear to be many young grapes this year. G.O., Fort Worth
Answer: In this case, I would use kaolin clay. Mix 1 quart of kaolin clay and 1 tablespoon of liquid soap with 2 gallons of water and spray the plants thoroughly. The white mineral film left on the leaves and fruit repels hard-to-control insect pests such as grasshoppers and should help repel birds. A commercial equivalent to my mixture is a product called Surround WP. I hope you won't have to resort to covering the plants with bird netting.
Apple tree treated with Kaolin Clay.
Photo from ARS