Our problems here including the rusts, cankers, rots, wilts, anthracnose, scales, galls, etc., etc. either exacerbate disease cycles or create them.
All borers (White oak borer, Oak timberworm, Columbia Timber beetle, Pin-hole borer, Twig pruner, Carpenter worm) and leaf eaters (Gregarious Oak leafminer, Oak Skeletonizer, Leafroller, sawfly, Gypsy moth, Forest tent caterpillar, Orangestripe oakworm, Fall cankerworm, etc.) have a larva stage at which they are susceptable to exposure. Same with fruit eating worm borers.
Soap (with trace phosphates) is itself a surfactant - something that alters the surface tension of water (makes it more wet). The detergent is the reaction of a wetting agent to break apart large or oily bonded substances. When detergent dries, it leaves a film on the leaf surface, like applying Salsa to your taco. If the soap hits the larvae, it becomes susceptable to exposure and dies, if the larvae consumes residue (if it still wants to eat the leaves in spite of the taste), it injests the adjuvant, killing it.
WE've had complete eradication when disrupting these feeding/breeding cycles with soap spray only. Perhaps due to unsubstantiated suspicions that insect vectoring of our known fungal diseases are reduced as a threat when populations are reduced, but the overall view seems to be that virulence of our other diseases seem to subside when we control some of the insect population outbreaks. Otherwise, we tend to leave alone the infestations occuring in the rural stands, mostly because we've noticed thru the years that the trees always appear to adapt to what man considers obnoxious. The tent caterpillars can cycle twice a year (for example) and completely strip miles of canopies, yet the timing is such that re-leafing is still viable, it being both late enough, or early enough in the tree canopy cycle to compensate the loss of leaves. However, someone with a patio, b-b-q grill and picnic table wants the ???? squirmy worms out of there, so we spray.
Sunlight brand (cheap) with lemon scent (has trace of citric oil) works wonders, has less phosphates than most name-brand soaps.
