Fungal Infections After Sporadic Rain

I love rain. There is a special joy to see rain dripping from trees and plants during warm weather days.  Our fields and country side benefit from the rain producing growth. Insects also respond to the humidity by hatching and multiplying. Fungi, and its relatives, the molds also respond to the rain by multiplying. It was common to see the reproductive stages of fungi growing even over manicured lawns in our square, product of microbial activity and growth. Earlier in the week , cases of fungal infections came to the Hopkins County Extension Office from tree owners and even homeowners and their lawns.  Referring to rust in lawns Richard Duble from Texas A&M AgriLife Extension wrote: “Rust diseases are found throughout the U.S. on most species of grasses. Bluegrass, ryegrass and zoysiagrass are most commonly affected. Rust diseases are favored by warm and humid conditions and develop most frequently on grasses subject to stress-droughty conditions, low nitrogen fertility and shade. Low mowing heights, particularly on Kentucky bluegrass, also increase the susceptibility of grasses to rust. Symptoms: The disease first appears on grass leaves as small orange to reddish-brown flecks that enlarge to form raised pustules on leaves and stems. Individual pustules are usually oval or elongated and contain a powdery mass of orange to reddish-brown spores. As the pustules mature they turn brown to black. Heavily infested turf becomes thin with an overall yellow-orange to reddish-brown color. Infected leaves turn yellow, wither and die. In southern states, rye grasses are highly susceptible to rust in the spring, particularly where nitrogen fertility is low. Zoysia grasses are most often affected by rust in the fall as the growth rate of grass slows and environmental conditions favor disease development. Control:. Cultural practices which improve the vigor of the turf help prevent rust. To reduce the incidence of rust, keep nitrogen levels adequate for turf growth, avoid moisture stress or overwatering and adjust mowing heights according to the grass needs. In the case of Kentucky bluegrass and perennial ryegrass, use varieties that have good resistance to rust where the disease is a problem. Where these measures fail to provide adequate control of rust diseases, fungicides are available for its control. Check on product labels for lawn compatibility, doses and application recommendations. For more information contact the Hopkins County Extension Office at 903-885-3443 or email me at [email protected]


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