A spray schedule will enable you to harvest good fruit from pear trees. According to Colorado State University, you'll have to modify your schedule during the growing season because various weather conditions will dictate the frequency of spraying. Perhaps the most important spray needed for pear trees is that of a quality insecticide. Not all insecticide sprays will eliminate all problem insects, so check labeling on containers to ensure your spray targets the insects you need to eradicate. Pears can be damaged by apple maggots, psylla aphids, moths and many other pests. Without an insecticide spray, the resultant fruit will be damaged by worms and other fruit pests.
Apply a dormant oil spray to the pear tree to suffocate any mites, scales or other insect eggs that are residing on the tree. Spray the tree in late March. Follow all label directions pertaining to the specific chemical being applied, as all manufacturers will use different strengths of concentrates. Add either a permethrin or malathion insecticide as an extra measure. Follow the container's labeling and mixing instructions. Apply the spray until it drips from the tree's limbs. Not all insecticides will treat all insect problems. Consult the containers labeling for the insects the product will control. If you are in a rainy climate, wait for a break in the rain to spray because the rain will wash off most fruit tree sprays.
Eliminate powdery mildew and other fungus by spraying the tree with a fungicide just before the blooms begin to break open. Follow the label mixing directions on the fungicide container. Add 2 to 4 tbsp. summer fruit tree oil per gallon of water. The summer fruit tree oil allows the fungicide to cling to the tree branches.
Reduce fire blight infection by mixing 1 tsp. streptomycin per gallon of spray water. Apply the spray every three days to five days during the bloom period.
Spray again with the fungicide and fruit tree oil mix after petal drop has occurred. This will prevent any fungus from forming on the developing fruit. Continue fungicidal treatment throughout the growing season if warm humid conditions exist. Moist conditions will promote the growth of fungus on the tree and the fruit. In most cases, fungicides are applied every 10 days to 14 days during the growing season, unless specified differently on the containers label. Follow all label instructions because some fungicides can only be applied a certain number times during the growing season.
Protect the pears by applying insecticide on the fruit trees every seven days to 10 days. This frequency depends on the amount of insect activity in your area. In some cases, with the coddling moth, the insecticide spray must be utilized throughout the growing season to the month of September. Follow all label directions on the insecticide container. You may be able to mix in the fungicide with the insecticide, and spray the pears trees with both chemicals. Consult the label directions of the chemical. Discontinue use according to the label directions prior to pear harvest.