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Issue link: https://read.dmtmag.com/i/86263
Landscape and Turf Maintenance It's time to rejuvenate lawns and get them ready for winter By Rob Golembiewski, Ph.D. lthough fall has just begun, it is not too early to start think- ing about rejuvenating lawns and getting them ready for winter. Unfortunately, turf pests may cause a decline in lawn quality (both aesthetically and functionally). The degree of turf deterioration is a function of the grass species, type of pest, and the environmental conditions before, during and following the pest in- volvement. Pests are part of any ecosystem, and managing turfgrasses to optimize their competitiveness is the essence of any pest manage- ment program. Rather than rely on a particular pesticide for con- trol, successful pest management must include the integration of proper cultural practices. Without optimum cultural practices, any pesticide solution to a pest problem will not be as effective as it could be, and is unlikely to be permanently successful. Disease control Disease can be defined as a continual disturbance of normal plant function by a pathogenic agent or environmental factor. Non-infectious diseases cannot spread between plants, and are caused by non-living agents such as drought, soil compaction, chemical burn or nutrient deficiency. Infectious diseases are caused by pathogenic agents (fungi, bacteria, viruses, nematodes) and are passed from plant to plant. Most turfgrass diseases are caused by fungi. The development of an infectious disease requires three things: susceptible host grass plant, presence of the pathogen, and a favor- able environment. The relationship between these components is called the disease triangle, and control tactics are aimed at elimi- nating one of the components. Methods of disease control include resistant varieties, cultural practices, biological control, and chemi- cal control. Numerous diseases can occur on lawns with some of the more common diseases outlined as follows: Fall Disease Prevention and Control A wetting agents, fertilize to mask rings Gray Snow Mold • Grasses affected: Annual bluegrass, perennial ryegrass, Ken- tucky bluegrass • Season: October-April • Symptoms and signs: Irregular, dead, bleached areas with gray mold • Conditions favoring disease: Air temperatures 32 to 36 de- grees Fahrenheit with deep snow falling on unfrozen ground, snow cover 40 to 60 days (mild disease), 60 to 90 days (moderate), greater than 90 days (severe) • Cultural control: Avoid late fall fertilization that leads to lush growth, control excessive thatch, remove tree leaves from turf, control drifting snow, promote rapid drying in early spring by re- moving snow or improving drainage Helminthosporium Leaf Spot and Melting Out • Grasses affected: All turfgrasses, especially Kentucky bluegrass and fine fescues • Season: All year, particularly spring • Symptoms and signs: Tan to purple spots on leaves with even- tual yellowing and thinning of turf • Conditions favoring disease: Spring and fall, temperatures 55 to 70 degrees Fahrenheit, with extended periods of rainfall and/or overcast weather • Cultural control: Raise mowing height, mow frequently to avoid stressing turf, avoid excessive nitrogen and thatch, irrigate sparingly during the day only when needed Microdochium Patch/Pink Snow Mold • Grasses affected: Annual bluegrass, perennial ryegrass, Ken- tucky bluegrass • Season: Late fall and early spring (Microdochium patch), under snow cover (pink snow mold) • Symptoms and signs: Browning and thinning of turf in large indefinite spots • Conditions favoring disease: Heavily thatched turf that is Fairy Ring • Grasses affected: All turfgrasses, especially Kentucky bluegrass • Season: April-November 8 Landscape and Irrigation October 2012 growing slowly, prolonged rainfall and air temperatures 35 to 60 degrees Fahrenheit, poor drainage, optimal is high humidity and air temperatures 32 to 45 degrees Fahrenheit, snow cover ideal for development • Cultural control: Maintain low soil pH (below 6.5) and bal- www.landscapeirrigation.com • Symptoms and signs: Rings of dark green; sometimes rings with dead zones, with or without tan mushrooms • Conditions favoring disease: Fungus thrives in warm and wet weather, but injurious effects not noticeable until hot and dry weather • Cultural control: Aerify, maintain adequate soil moisture, use All photos courtesy of Bayer CropScience LP