12/8/2023 0 Comments Pythium blight control![]() ![]() High soil salinity can actually facilitate Pythium infection in conditions of drought. ![]() When this is the case, Pythium blight is able to survive and favors lower temperatures and humidity levels than usual. Other conditions that help this disease thrive are soil types with high salinity. It is fairly common to develop first in low areas of the lawn and on cool-season turfgrass varieties. When conditions are optimal, this pathogen has the ability to destroy an entire turfgrass stand in less than a week. Overall, weather conditions that include hot temperatures, cloudy skies and either rain or humidity (greater than 90 percent) is ideal. For this disease, a preferred day temperature is above 82 degrees Fahrenheit and a preferred night temperature is above 68 degrees. Pythium blight favors weather that is warm and humid and tends to be most prominent when the turfgrass tissue has been moist for a minimum of 12 hours as this promotes infection. Pythium blight may also show up as fluffy cotton-like growth on foliage, especially when leaves remain wet for a substantial amount of time. This pathogen can also cause root and crown rot. If the pathogen infects a water source and is spread to a new area, the patches may appear as streaks through the lawn this can also happen when the mowing equipment is infected. As the pathogen kills the plant tissue, the grass will shrivel and eventually fade to brown or gray. The infection can enlarge and form one massive patch on a lawn, which can cause severe damage, especially for field turf and golf courses. Infected plant tissue will not form any spots or lesions they mainly just feel slimy when touched. These patches can be anywhere from under 1 inch to over 8 inches in diameter. ![]() The infected spot will appear to be soaked and will form patches on the turf grass, either irregular or circular in shape. When plant tissue first becomes infected, tissue is darker green and sometimes purple in color. Pythium Blight Identification and Habitat Spread can also occur when infected equipment, soil, or mower clippings are moved to uninfected areas. During wet conditions the spread of this disease occurs quite easily. Oospores can be found in the roots and leaves of turfgrass. These oospores can survive in dry environments and can live for as long as 12 years. The egg cell walls will thicken to create an oospore with the zygote inside. Egg fertilization occurs and a zygote is formed. This pathogen will reproduce sexually when common strands come into contact with one another. Under unfavorable conditions, zoospores will not live long. When they find a suitable host, they remain there and germinate, forming a germ tube that will infect the host plant. Zoospores form inside and when the wall of the sack ruptures, these spores can move freely using flagella in water on plant tissue or in the soil. During asexual reproduction, they create structures similar to sacks where they can germinate when mature. These pathogens can reproduce both asexually and sexually. More severe cases are often associated with P. However, there are still numerous other species that are capable of causing Pythium blight, they are just not as common. This disease is mainly caused by 2 different Pythium species: Pythium aphanidermatum and Pythium ultimum. Pythium blight is caused by organisms that are similar to fungi and are sometimes referred to as water molds. ![]()
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