When to spray those apple, pear trees
March 14, 2014
A number of homeowners like to grow their own apples and pears for home consumption. To consistently harvest a good crop of quality fruit, it is advisable to follow the recommended spray schedule and prevent the disease and insect problems that often occur.
Some of the insect pests that infect apple and pear trees can be scouted for and successfully treated if found early, but in most cases, both insects and diseases are best managed with preventive measures.
The first several spray applications will be with the fungicide captan, to prevent the fungal disease, scab, which can infect both apples and pears. Plant stage and the approximate range of calendar dates for these applications will be: silver-tip bud stage – 4/10-20; green-tip bud stage – 4/20-30; tight cluster bud stage – 4/25-5/10; and pink to full bloom stage – 5/1-15. Scab can also be managed by planting resistant or immune varieties, raking and destroying the previous years' leaves and pruning the trees in late winter to maintain an open canopy to allow good air circulation, faster drying conditions and better penetration of spray applications.
The next application should be at the bloom stage, approximately 5/15-30, again with captan, or possibly alternating with thiophanate-methyl to reduce the chance of fungicide resistant scab fungi. The target diseases are scab, and powdery mildew. Insecticides should not be used during the bloom stage since they are highly toxic to bees.
An application of all-purpose mixture with captan (or thiophanate-methyl) should go on at petal-fall, approximately 5/15-30, again targeting scab and powdery mildew, along with insects; codling moth, curculio, tent caterpillars, mites and aphids. All-purpose sprays contain both insecticide and fungicide. Commercial blends are available or homeowners may mix their own in the spray tank, using espenvalerate, malathion, permethrin or carbaryl insecticides with captan (or thiophanate-methyl) fungicide.
The remaining spray applications are "cover sprays", which can begin 10-14 days after the petal-fall application, and repeated every 10-14 days up until the harvest limits of the product used. The same all-purpose mixture with continue to be used, with the target pests. In addition to the diseases and insects targeted earlier, the July cover spray is intended to prevent apple maggot infestations.
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This "spray schedule," along with a table providing guidelines on how much spray solution to apply to various size trees and a wealth of other disease control information can be found in the factsheet, FS934, "Managing Plant Diseases in the Home Garden". This factsheet can be obtained at SDSU Extension Centers, County Extension offices or online at: http://pubstorage.sdstate.edu/AgBio_Publications/articles/FS934.pdf. F