Pythium volutum

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Pythium volutum
Systematics
Department : Egg mushrooms (Oomycota)
Class : Oomycetes
Order : Peronosporales
Family : Pythiaceae
Genre : Pythium
Type : Pythium volutum
Scientific name
Pythium volutum
Vanterp. & Truscott

Pythium volutum is a phyto-pathogen belonging to the Pythiaceae familywithin the group of egg fungi . It infects wheat , barley and turf- forming grasses. It appears to be sensitive to some constituents typically found in selection media for Pythium species, so alternative methods should be sought for its isolation.

Hosts and Symptoms

Pythium volutum causes a disease in turf -forming grass species that is accompanied by a widespread bleaching of the plants, which particularly affects white ostrich grass . White ostrich grass is used on many golf course greens . The majority of the infectious events have occurred in the southeastern United States. This regional concentration is due to the ideal environmental conditions for the pathogen there. When white ostrich grass is infected, extensive chlorosis , wilting and symptoms of drought stress appear. In the case of white ostrich grass, large patches of dead grass can be observed. These symptoms are most commonly seen during the summer months, when the soil and soil surface temperatures are high. Because Pythium volutum is a root rot pathogen, the grasses' ability to absorb water is inhibited. At high soil and soil surface temperatures, the plants show symptoms of wilting and chlorosis, which eventually lead to death. Poor nutrient intake, low oxygen levels in the soil, and drought stress can exacerbate symptoms. While these symptoms are most pronounced at high temperatures and low humidity, infection occurs at lower temperatures and higher soil humidity.

Combat

In order to combat Pythium volutum Wirkdam, a few steps are required. Some steps in growing are monitoring irrigation and promoting aeration through drainage. Because Pythium species are moisture-dependent (hence the English term "water molds"), clever irrigation management can reduce the risk of infection. Aeration of the soil will also do this, as the water can escape better. Discharging the escaping water prevents the spores from moving from root to root. Finally, mulching reduces stress on the plants and makes them less susceptible to infection with the pathogen. Chemical agents are another option for treatment and control. Fungicides can be applied during the infectious period to reduce the risk of infection. In fact, both cultivation and chemical control should be used together for the best results. Fungicides kill the egg fungi and their spores and effectively fight the pathogens.

Life cycle

Starting from an infected, dead plant, Pythium volutum enters its sexual phase. In this phase, an oogonium is fertilized by an antheridium . Pythium voultum is normally fertilized by a single antheridium, but four simultaneous fertilizations have been observed, which distinguishes the species from other Pythium species. After fertilization, an oospore is created, a permanent stage that also enables wintering in the soil. As soon as the oospore is formed, it can produce or germinate zoospores and directly infect new plants itself. For this reason, either the oospore or the zoospores can be considered as the initial inoculum . A release of the zoospores is water-dependent, as they swim to the hosts. As soon as they have reached the host tissue, they infect it. This infection is systemic and ends with the symptoms described and the death of the plant. Before the plant dies, the pathogen forms so-called sporangia . These can be spread by wind, rain or mechanically and infect new hosts. As soon as the sporangia encounter a new host, zoospores are released that use existing water to swim to openings or wounds in the ostrich grass. Here the infection differs from that of the initial inoculum because the spores also penetrate the host through other parts of the plant than the root tissue. After that, the plant will eventually die and the pathogen will hibernate again as an oospore. An infection of the plants occurs in spring or autumn, at a time with optimal temperatures and humidity conditions.

Individual evidence

  1. ^ Pythium Root Dysfunction in Turf . In: NC State Turf Files . North Carolina State. Retrieved August 6, 2019.
  2. ^ A b Steven Vann, Aaron Patton: Pythium Diseases of Turfgrass . In: Agriculture and Natural Resources . September, pp. 1-4.
  3. ↑ A. Downer, MA Harivandi, F. Wong, J. Hartin, ME Grebus: How to Manage Pests- Turfgrass Pythium Root Rot . In: UC IPM Online . University of California, Agriculture & Natural Resources. Retrieved August 6, 2019.
  4. ↑ James P. Kerns, MD Soika, LP Tredway: Preventive Control of Pythium Root Dysfunction in Creeping Bentgrass Putting Greens and Sensitivity of Pythium volutum to Fungicides . In: Plant Disease . 93, No. 12, 2009, pp. 1275-1280. doi : 10.1094 / PDIS-93-12-1275 .
  5. ^ TW Allen, A. Martinez, LL Burpee: Pythium blight of turfgrass . In: The Plant Health Instructor . 2004. doi : 10.1094 / PHI-I-2004-0929-01 .

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