In the heat of August, a juicy pear contains just the right sweetness to summon memories of cool springtime blossoms. If you garden in U.S. Department of Agriculture plant hardiness zones 5 through 8, there are pear trees (Pyrus commmunis) for your orchard. Specialized pears grow as far north as USDA zone 3 and as far south as zone 10. Some common pests can threaten the health of your trees but prevention and natural treatments minimize their dangers.
The first line of defense for your fruit trees is good sanitation. Many pests lay eggs in leaves and fruit that fall to the ground, where larvae hatch and climb back up trees to infect more fruit. Pick up and destroy dropped fruit and leaves that exhibit dark, sooty mold -- never add them to compost heaps. Beginning each spring, cultivate ground beneath trees to disrupt colonies and keep sheltering weeds at bay. Cultivation must be shallow, though, to avoid damaging shallow tree roots. Wrap tree trunks with corrugated cardboard to keep larvae off the tree bark, then remove and destroy the cardboard in early winter when the largest population has sheltered in it.
Common pear pests, pear psylla and codling moth reproduce three times per year, so use monitoring traps to cue the optimum time to use horticultural oils and insecticidal soaps. Pearslugs and California pear sawflies attack foliage, eating along veins. Use a sharp spray of water to dislodge them in home orchards. Search for pests in upper branches where dormant oil and other sprays may not reach or in pheromone traps or sticky cards designed to sample populations.
Place pheromone traps 6 to 8 feet high in the pear tree's canopy and check weekly. Follow manufacturer instructions and store unused traps inside the refrigerator or freezer.
Use a ready-to-use insecticidal soap or horticultural oil formula and spray all surfaces of the foliage, including the underside of leaves. Do not use if temperatures are above 90 degrees Fahrenheit or leaf damage can occur.
Leafrollers -- obliquebanded, omnivorous and fruit tree -- are sometimes found, especially where pesticides have been used on codling moths. Leafrollers fall to parasitic wasps or Bacillus thuringiensis sprays. Webspinning and European red mites thrive in hot, dusty conditions -- watering during dry spells and predatory mites help control them. Any of a dozen other pests may wander into your garden if there are orchards nearby. Abandoned orchards pose a hazard because of the weeds and rotting fruit that make a permanent breeding ground for pests. Winter dormant and growing season horticultural sprays suffocate migrating larvae.
Pest populations vary in different areas and peak at differing times. Some preparations, such as dormant oil sprays sold in premixed solutions, help prevent infestations. To find out which pests are active in your area, check with your local agricultural extension officer or Master Gardener organization. They can help with timing for sprays for your particular location. They also know which predators, such as lacewings, pirate bugs and predatory mites target specific pests -- and where to buy them.
Cover all plant surfaces with a ready-to-use dormant oil spray being sure to spray the underside of leaves. Do not use if temperatures are above 90 degrees Fahrenheit or foliage damage can occur.