• Do not try to control crabgrass after mid-July with a post-emergence herbicide. It is often too large to control well. Live with it until it dies from frost.
• To prevent grub damage in the lawn, apply insecticides containing halofenozide or imidacloprid. Or, wait until August to determine if you have a problem and apply curative controls.
• Tan to brown streaks may appear in unirrigated lawns during dry weather due to mower damage. Consider delaying mowing (as growth allows) until sufficient rain is received.
• Early leaf-rust infections may occur in the lawn at this time. For severe infections, apply a half-rate of a slow-release high-nitrogen fertilizer.
• Animal urine can damage any lawn under the right conditions but damage is often more severe during extended hot, dry weather.
• Keep mower blades sharp. A dull mower blade can cause a whitish cast to the lawn and provide a good opportunity for some disease organisms to infect the plant.
• Buy high-quality grass seed and begin planting or reseeding lawns in mid-August. The optimum time to seed a lawn in central Indiana is mid-August to mid-September.
• Regular lawn watering in August and September (if needed) may allow the turf to outgrow damage from light populations of white grubs without using insecticides.
• Thorough site preparation is the most important factor determining the success of a sodded lawn. Site preparation for a sodded lawn should be similar to that of a seeded lawn.
• Check the lawn for damage caused by white grub feeding. If necessary, apply a quick-acting, curative insecticide such as trichlorfon.
• Distinctive circular leaf notches on roses, redbuds and other plants are caused by leaf cutter bees. Plant damage is not significant, so do not kill these beneficial pollinators.
• Kill unwanted crabgrass growing in flower beds and shrub borders with labeled, post-emergent, selective grass herbicides containing sethoxydim or fluazifop-butyl.
• If needed, dig and divide bearded iris one to two months after bloom (July-August) to establish plants before winter. Cut leaves to one-third their height. Do not cover the top of the rhizomes with soil or mulch.
• Check burning bush, honeylocust and other deciduous plants regularly in hot dry weather. Honeylocust mite and twospotted spider mite populations can multiply rapidly in the heat.
• White patches of powdery mildew may be seen on the leaves of garden phlox. To control, plant resistant cultivars, thin emerging shoots in the spring or use a fungicide.
• Refrain from pruning and fertilizing trees and shrubs in late summer to avoid stimulating succulent new growth that may suffer winter dieback.
• Plant autumn crocus (Colchicum autumnale) in late summer or early fall as soon as it arrives at garden centers. This highly toxic plant blooms without foliage in the fall and leaves appear in spring.
• It is too late to spray for bagworms when they have tied the top end of their bag to the twig. If practical, handpick the bags or mark your calendar to spray in June next year.
• The ideal time to plant daylilies is mid-August through September.
• Excessive leaf drop on crabapple trees is often caused by the disease apple scab. To avoid the problem each year, replace the tree with a resistant crabapple variety.
FRUITS AND VEGETABLES
• Spots on grape leaves may be due to the diseases anthracnose or black rot. Not much can be done at this time for control. Pick off and destroy diseased parts and plan a control program for next year.
• Hot dry weather can cause a bitter flavor in cucumbers. Keep plants watered and mulched for the rest of the summer.
• Pick off and destroy tomatoes affected with blossom end rot, a non-parasitic disorder. Control by providing an even moisture supply, using mulch, and avoiding excess nitrogen.
• Remove water sprouts (vertical sprouts from major branches and the trunk) and suckers (sprouts from the roots) that appear in fruit trees.
• Keep beans, tomatoes, peppers, okra, cucumbers and squash picked to encourage further production.
• Try to finishing seeding beets, kohlrabi, kale, Swiss chard, turnips and
bush beans in early August and seed leaf lettuce and spinach by late August. Complete planting broccoli, cabbage and cauliflower transplants in mid-August.
• Apple harvest begins for fresh eating apples like Redfree and continues through October with apples such as Winesap and Rome.
• Strawberries should receive 1 inch to 1.5 inches of water per week during dry periods in August and September. This will help fruit bud formation for the following year and increase yields.
• Dry bulb onions are ready to harvest when most of the tops have fallen over and the necks have shriveled. Pull and dry for two to four weeks in a location out of direct sun.
• To reduce potential insect and disease problems, prune and destroy the current fruiting canes of raspberries and blackberries after harvest.•
This calendar is from Steve Mayer, a horticulture educator with Purdue Extension-Marion County. For more information on gardening, contact the Purdue Extension-Marion County Master Gardener Answerline at (317) 275-9292, or e-mail: email@example.com.