By Amy Brothers
Oklahoma County Extension Educator, Horticulture
A common pest noticed this time of year is the Oak-Leaf Skeletonizer. Damage is identified by a translucent, lacy appearance of Oak tree foliage. The larvae of the Oak-Leaf Skeletonizer feed on the underside of leaf surfaces, leaving the upper surface and veins intact. Heavy populations may cause leaf browning and premature defoliation.
The skeletonizer overwinters as a cocoon on the bark of trees, fallen leaves, and the sides of buildings. The first generation of the year emerge as adults to mate and lay eggs in May through Mid June. Eggs hatch within two weeks and the first generation of feeders begin to do damage at this time. By late June and July these larvae have become fully grown, and pupation begins.
The second generation of adults emerge in July and August, again, mating and laying eggs that will hatch in about two weeks. This second generation of feeding larvae are out now.
The adult is a moth, off-white with brown markings and a wing span of just over 1/4-inch. Larvae are greenish yellow and about 1/4-inch long when fully grown. Larvae spin webs on the underside of leaves where they molt when growing. In heavily infested trees, these silk threads may be a nuisance.
In most cases, damage to the tree is minimal, affecting only 25 or 30 leaves of a full grown oak. However; for good control in heavily populated trees, it is best to spray insecticide when the larvae are actively feeding. And remember they are on the underside of the leaves, so directing spray to the bottom of leaves is helpful.
It is important to monitor these pests to make sure damage is bad enough to justify a spray treatment. If treatment is needed, they are easier to control when they are feeding in the larval form.
Garden tips for August:
--Continue protecting the fruit orchard with insecticide applications. A good spray schedule is often abandoned too early. Follow directions on last application prior to harvest.
--Always follow directions on both synthetic and natural pesticide products.
--Soak vegetables' seed overnight prior to planting. Once planted, cover them with compost to avoid soil crusting. Mulch to keep planting beds moist and provide shade during initial establishment. Monitor closely, and control insect pests that prevent good establishment of your fall garden.
--Water compost during extremely dry periods so that it remains active. Turn the pile to generate heat throughout for proper sterilization.
--Discontinue deadheading roses by mid-August to help initiate winter hardiness.
--Irrigated lawns can be fertilized once again. If you have had a problem with spring dead spot in your Bermuda lawn, this should be your last application of fertilizer for the year.
--Watch for high populations of worms, aphids, spider mites, thrips, scales, and other insects on plant material in the garden and landscape and treat as needed.
--The rule of dividing a perennial flower is: Divide it in the fall if it flowers in the spring; divide it in the spring if it flowers in the fall.
--August is the best time to divide daylilies and Bearded iris. This is the common iris found blooming in the spring.