Surround WP is my favorite pesticide. Surround and the occasional small dose of Bt is all I need in a good year, and in a bad year I add in some Serenade for the cherry trees that are particularly prone to brown rot.
Surround is 95% kaolin clay, sold in powder form to be mixed with water and sprayed, as explained in the Fedco Organic Grower’s Supply catalog:
Surround™ WP Crop Protectant Forms a particle film which coats the surface of leaves and fruits, creating a barrier which acts as a broad-spectrum crop protectant, reducing damage from various insects, mites and disease-carrying pests. Recommended for controlling European apple sawfly, plum curculio, Japanese beetles, leafhoppers, CPB, thrips and other maleficial insects on fruit crops and field crops, effective against cucumber beetles on cucurbits. 95% kaolin clay, Surround’s layer of white particles creates an unfamiliar environment for the attacking insects, prevents them from recognizing their target, and, if they land, the particles rub off on them causing irritation and excessive grooming. The white surface also reflects sunlight, preventing sunburn and heat damage. Michael Phillips at Lost Nation Orchard estimates that one 25# bag is sufficient to treat 10 trees for one season. Begin application before petal-fall. Apply 2–3 times the first week to build up a good coating and then every 10–14 days or as the film weathers or new growth appears, more frequently in rainy weather. Maintain a good coat until plum curculio season ends, around June 30 in central Maine.
Agricultural Solutions also has an informative entry:
Surround W. P. is made from 95% kaolin clay, a naturally occurring mineral. When applied to fruit trees, crops, and other plants, it forms a white film. Surround suppresses a wide range of pests, especially those which damage fruit crops including pears, apples, grapes, berries, and some vegetables. The manufacturers use a super-magnetic centrifuge in Georgia to refine the impurities out of raw kaolin and then filter the clay particles to a critical 1.4 microns in size.
I really like the part about the centrifuge.
The best technique I’ve found for my 2 gallon hand pump sprayer is to mix the 2 gallon dose of powder into a quart mason jar of water and shake well for at least 30 seconds, then dump the mixture into the full (minus 1 qt) sprayer. Agitate the sprayer during use. Several sources comment that hand sprayers are a good way to apply this agent because you can really pay attention to coverage. The best thing about Surround is that I don’t have to closely monitor what it falls on under the trees: it is rated for vegetables, it won’t harm the grasses and wildflowers, and it washes off the occasional Adirondack chair (although that takes a few days – move furniture and cover paving stones if you don’t want them temporarily decorated with faint white patches).
I also find that a good coating of Surround reduces deer predation. Perhaps it limits the aroma of an attractive plant? Here I’ve sprayed some mallow growing outside the electric fence – normally a tempting target and they’ve left it alone all season.
The weekend is forecast to be sunny and not too breezy – time to apply another coat!