Members of the genus Pythium belong to a group of organisms known as “oomycetes”, a group of filamentous protists belonging to the pseudofungi group, which survive year after year as oospores on our greens or soccer fields, and are also very mobile through the movement of irrigation water, our mowers or the players themselves.
These oomycetes produce sporangia, sac-like structures, which vary in shape from filamentous to spherical. Once these sporangia mature, they can germinate and produce zoospores, which swim freely in soil pore water or on the surface water of our lawns. This characteristic gives it its great capacity for infection.
One of the major problems of Pythium is its high mobility.
There are several diseases caused by Pythium, particularly on cool season sports surfaces. Pythium aphanidermatum is the main cause of “Pythium blight”, frequent on fairways, tees or soccer fields, and infrequent on greens.
Pythium blight can occur at temperatures between 13 – 18 ºC, although it tends to occur with greater frequency and intensity in a higher temperature range, daytime temperatures of 30-35 ºC and nighttime temperatures above 20ºC.
Favorable conditions for the disease are high relative humidity, excess nitrogen fertilization, saturated soils with intense periods of dew and poor ventilation.
On the other hand, the disease known as “Pythium root dysfunction”, which is very harmful in Agrostis greens and is caused by Pythium volutum, is more frequent in greens. The pathogen infects the roots during the fall and spring, reducing their ability to absorb water and nutrients, so the symptoms are even more important in the summer. They appear as irregular circles or patches with symptoms of wilting or nutritional deficiency. They present a serious affection of the root system (dark color), which can lead to irreparable damage in the summer season.
Its appearance is irregular yellowish or orange spots.
Pythium root rot is a persistent disease in poorly drained areas with excessive rainfall or irrigation and on greens with excessive matting. It can occur at any time of the year on heavily saturated areas. Symptoms are orange or yellow areas with irregular shapes.
Infections in sowings are also frequent, these infections are known as “Damping off”, caused by different species of Pythium, due to excessive doses of sowing under excessive moisture conditions, low aeration, etc..
Nowadays, there are less and less fungicides allowed for our agronomic management, so it is necessary to monitor the values in which parameters such as relative humidity, %VWC, Tª reach key values in the proliferation of these infections. We can use some products based on phosphonates with properties that, through their continued use, can help us to reduce the incidence of this disease.
Know exactly which Pythium species you have through correct identification with qPCR analysis or use your own Phytfieldlab kit for this purpose.