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is applied in the spring, and then etho- fumesate (postemergence herbicide) in ap- plied the subsequent fall. Herbicides provide excellent weed con- trol, but timing, rate, and application inter- vals are of utmost importance. Application may interfere with cultural practices, turf- grass germination and growth, so learn to adapt and proceed with caution. Learn the traits of each active ingredient (AI) in her- bicides as they are put in differing combi- nations more and more. Disease management Spring dead spot is a serious disease of bermudagrass, especially in the transition zone. Fall infections predispose turf to winter kill. In the following spring, circular patches appear to remain dormant, while roots, rhizomes and stolons are sparse and dark-colored. The cool and moist condi- tions in autumn and spring promote dis- ease development. Management practices that increase cold hardiness generally re- duce disease incidence. Maintaining bal- anced fertility and proper thatch management will reduce disease activity while promoting healthy turfgrass. Brown Patch and Pythium blight are often the most serious diseases on cool sea- son grasses. Brown patch is a foliar blight resulting in necrotic leaves and circular brown patches up to 4 to 6 feet in diameter. High humidity and temperatures, combined with excessive nitrogen levels increase dis- ease activity and severity. To minimize dis- ease severity avoid nitrogen application when the disease is active, allow the foliage to dry between irrigation events, and re- move excessive organic matter with cultiva- tion. There are many fungicides that will provide excellent control of brown patch. Check the labels for information. Pythium blight starts as small, irregular spots, which initially appear dark and water-soaked. Affected turfgrass collapses, appears oily and matted and dies rapidly. White, cottony mycelia may be evident early in the morning. Pythium blight is en- couraged by hot-wet weather, which cor- relates to increased stress on the turf. Cultural practices for control of brown patch will also help to minimize Pythium development. Note that correct diagnosis is important because Pythium control re- quires specific fungicides. www.landscapeirrigation.com Grub sampling using a flat edge shovel (left) and white grubs of Japanese beetle (right) collected in June. — Photos cour- tesy of Alec Kowalewski. Insect management White grubs are the larvae of several species of scarab beetles and are typically the injurious stage to turf. Grubs are white, C-shaped insects that have three pairs of legs and a distinct, brown head. Common grubs affecting turf include chafers, May beetles, June beetles and Japanese beetles. Grubs feed on the turf roots, substantially compromising the stress tolerance of the above-ground foliage. In heavy grub infestations, roots are pruned to the extent that the turfgrass withers and dies and can easily pulled up. Because grubs tend to be in clumped populations, it is important to look in sev- eral areas using a spade to check the root zone in the spring and fall. Typically, five grubs per foot in un-irrigated turf and 15 in irrigated turf indicate the need for treat- ment. Turf under heavy traffic will be less tolerant of grub injury. Effective curative products for late instar control include trichlorfon or carbaryl. Pre- ventive applications can be very effective using imidacloprid, thiamethoxam, or chlo- ranthaniliprole. Effective combination prod- ucts, designed to control soil insects and surface feeders include, imidacloprid and bifenthrin or clothianidin and bifenthrin. The neonicotinoid insecticides used for grub control have very low mammalian tox- icity while being very effective grubicides. During dry weather the turf should be irri- gated prior to treatment to help the insecti- cide penetrate grass blades and dry thatch. Armyworms, which are caterpillars of moths, are greenish when small, but be- come brown with several lengthwise stripes when fully grown at 1/2 inch. The adult is a mottled brownish-gray moth with a wingspan of nearly 1-1/2 inches. Annual bluegrass in hybrid bermudagrass emerging from winter dormancy in February, Tifton, Ga.. Photo courtesy of Alec Kowalewski. Landscape and Irrigation 23 Irritant sampling with dish soap is par- ticularly useful in detection and monitor- ing of armyworm, as well as mole crickets, cutworms, or sod webworm infestations. The soap irritates sensitive soil-inhabiting pests causing them to quickly come to the surface. When using this monitoring method mix one ounce liquid detergent per gallon of water and apply to one square yard. For best results apply insecti- cide in the early evening when caterpillars are actively feeding on turfgrass. Alec Kowalewski is an assistant professor at Abraham Baldwin Agricultural College, Tifton, GA. Aaron Hathaway is a research assistant, Crop and Soil Science, Michigan State Univer- sity. A. Martinez-Espinoza is an associate pro- fessor of Plant Pathology, University of Georgia-Griffin Campus. S. Kristine Braman is a professor of Entomology, University of Georgia-Griffin Campus. LI