Using captan alone in early cover sprays will provide good control of black rot, but it will not adequately control cedar rust or mildew infections on the developing terminal leaves. Captan used alone is also rather weak against sooty blotch and flyspeck, although it will provide adequate control under light to moderate pressure if applied every 10-14 days. The best fungicide programs will be ineffective if other orchard management practices result in poor spray coverage or inappropriate fungicide application rates. Thus, black rot can be effec tively controlled only if trees are pruned annually to allow proper spray coverage, if sprayers are properly calibrated, if nozzles are correctly aligned to allow coverage on fruit on low drooping limbs, and if travel speed during spraying is adjusted to ensure an adequate air stream for moving the fungicide spray to the centers of the tree canopies. By midway through the growing season, the majority of leaves are hardened off and psylla development then may be limited primarily to the water sprouts.
Honeydew injury occurs when excess honeydew drips onto and congregates on lower leaves and fruit.
The honeydew is a good medium for sooty mold growth. When it occurs on the fruit, it russets the skin and makes the fruit unsaleable. However, to obtain commercially acceptable fruit in New York, pear psylla must be controlled with insecticides. For psylla control, we have historically recommended an application of an effective insecticide when nymphs start to build to the level of 1-2 per leaf after petal fall. Repeated applications of a given material are often necessary.