SportsTurf provides current, practical and technical content on issues relevant to sports turf managers, including facilities managers. Most readers are athletic field managers from the professional level through parks and recreation, universities.
Issue link: https://read.dmtmag.com/i/60100
(Disarm), myclobutanil (Eagle), thio- phanate methyl (3336) among others). 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 4-6 ft in diameter (Image 5). High humidity and tempera- tures, combined with excessive nitrogen lev- els increase disease activity and severity. To minimize disease severity avoid nitrogen ap- plication when the disease is active, allow the foliage to dry between irrigation events, and remove excessive organic matter with cultivation. 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 (Image 6). Affected turfgrass collapses, appears oily and matted and dies rapidly. White, cottony mycelia may be evi- dent early in the morning. Pythium blight is encouraged by hot-wet weather, which correlates 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 requires specific fungicides, such as fosetyl-al (Aliette, Chipco signature) and/or mefenoxam (Subdue MAXX) among others. 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 compromis- ing the stress tolerance of the above ground foliage. In heavy grub infestations, roots are pruned to the extent that the turfgrass with- ers and dies and can easily be 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 (Image 7). Typi- cally, 5 grubs per foot in un-irrigated turf and 15 in irrigated turf indicate the need for treatment. Turf under heavy traffic will be less tolerant of grub injury. www.stma.org SportsTurf 13 >> IMAGE 6: Signs (top) and symptoms (bottom) of Pythium blight. Photos courtesy of Lee Burpee. Effective curative products for late instar control include trichlorfon (Dylox) or car- baryl (Sevin). Preventive applications can be very effective using imidacloprid (Merit), thiamethoxam (Meridian), or chloran- thaniliprole (Acelepryn). Effective combina- tion products, designed to control soil in- sects and surface feeders include, imidaclo- prid and bifenthrin (Allectus) or clothianidin and bifenthrin (Aloft). Sports >> IMAGE 7: Grub sampling using a flat edge shovel (top) and white grubs of Japanese bee- tle (bottom) collected in June. Photos courtesy of Alec Kowalewski. Continued on page 45