Pythium aristosporum
| Pythium aristosporum | ||||||||||||
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| Pythium aristosporum | ||||||||||||
| Vanterp. |
Pythium aristosporum is a phyto-pathogen from the group of oomycete that at White bentgrass a dysfunction caused by the roots.
Hosts and Symptoms
Pythium aristosporum causes root dysfunction in white ostrich grass ( Agrostis stolonifera ). White ostrich grass is a grass used on the greens , fairways, and tees of golf courses in the northern United States because it can be cut very short (0.125 in (3.2 mm)) and survives the winters relatively unscathed. It's ideal for golf courses because it creates side shoots so it can spread quickly and form dense stands on the ground.
As indicated, Pythium aristosporum attacks the roots of the white ostrich grass. While there are no macroscopic signs, some above and below ground symptoms indicate the infection of the plants. Above ground, the tip of the leaf wilts and the grass changes color from rich green to yellow-brown, which typically takes place in circular spots. The underground symptoms are secondary and result from root necrosis ; this dies, becomes pale yellow-brown and loses its root hairs . These symptoms are systemic in that they affect the entire plant, and most of the dead root tissue is a primary symptom as the death is a direct result of Pythium infection.
Hyphae are visible microscopically . In Pythium species, the primary structures needed to survive are oospores and sporangia . Oospores and sporangia have a circular outline. Antheridia and oogonia can also be present on the cells of the hyphae. An oogonium is circular in outline and connected to a hypha, and an antheridium looks like a branch of a hypha that is connected to the oogonium to create oospores.
Disease cycle
Pythium aristosporum infects plants in a variety of ways, such as via the air, via water, through wintering in the soil, agricultural engineering and already infected plants. In terms of the cycle, the wintering oospore should be taken as a starting point. The oospores on a plant can use a germ tube to penetrate the plant. If it is not already on a plant cell, the oospore releases a zoosporangium, which in turn releases zoospores into the environment. These zoospores have two flagella and are therefore mobile; they need water to move and to spread. Once on a plant, they encyst and develop haustoria to draw nutrients from the cell. Once established in the cell, the mycelium spreads through the plant. Sporangia then rise out of the mycelium and infect the cells directly or release further zoospores for infection. From there the mycelium can spread and the cycle starts all over again. Since this can be done more than once per cultivation cycle, it is called a polycyclic disease. When conditions are no longer suitable for growth and survival (very dry or cold), or when the host plant has died, haploid antheridia and oogonia fertilize to form diploid oospores.
Environmental conditions
Environmental conditions play a key role in the development of the pathogen in the plant. Even if the host and pathogen are present, environmental conditions will determine whether a disease breaks out. The root dysfunction caused by P. aristosporum ( English pythium root dysfunction , "PRD") develops in the roots of the white ostrich grass in autumn, winter and spring when the average soil temperatures between 50 ° F (10 ° C) and 70 ° F (21 ° C). The pathogen reduces the roots' ability to absorb water and nutrients from the soil, making the disease much more serious during times of stress , e.g. B. with low soil fertility, low soil aeration and especially drought. Therefore, symptoms tend to appear during warmer periods in summer when soil temperatures have reached the target range.
Because the disease affects the roots so severely, white ostrich grass does badly on sandy soils because these soils have high infiltration and flow rates. Grass sods in soils with a high organic content are better equipped (once infected) because these soils retain water and nutrients better and thus give the roots the opportunity to absorb them at lower rates than is the case in well-drained soils. While soils that better retain moisture available to higher plants allow these once infected plants to survive better, the best prevention is possible on soils that guarantee rapid drainage of the water. A water-saturated soil allows the zoospores to spread and infect the root cells, so the best prevention is to prevent long-term water saturation.
Insects like weevils can also act as vectors by transferring the spores or gnawing roots, creating openings that make it easier for egg fungi to enter.
Web links
- Pythium aristosporum in the Fungorum index
- USDA ARS Fungal Database
- Pythium aristosporum in the Taxonomy Backbone of the Global Biodiversity Information Facility
- Pythium aristosporum by Mycobank.org (English description)
Individual evidence
- ↑ a b James Kerns, Lane P. Tredway: Pythium Root Dysfunction Of Creeping Bentgrass . January 25, 2010. Retrieved July 15, 2019.
- ↑ William Stein: bentgrass . Retrieved July 15, 2019.
- ^ A b Miller, Burns, Brandenburg, Milla-Lewis: Pythium Root Dysfunction In Turf . Retrieved July 15, 2019.
- ↑ Plant Disease . Retrieved July 15, 2019.
- ↑ a b c Diseases Of Bentgrass Caused By Pithium . Accessed on July 15, 2019 ( page no longer available )
- ^ Pegg, Manners: Pythium Species - A Constant Threat To Nursery Production . 2014. Retrieved July 15, 2019.
- ↑ Plant Disease Management Strategies . 2018. Retrieved on July 15, 2019. ( Page no longer available )
- ↑ George Agrios: Transmission Of Plant Diseases By Insects . Retrieved July 15, 2019.