Language
Country/Area
No result found
Plant struggles: Which legumes are most resistant to Aphanomyces euteiches?
Aphanomyces euteiches is a water mold or inferior fungus that is a plant pathogen and causes Aphanomyces root rot. The pathogen can infect a variety of legume crops, and its symptoms vary between different hosts, but in general, they cause a reduction in root volume and function, leading to plant stunting and leaf yellowing. Aphanomyces root rot is an important agricultural disease in the United States, Europe, Australia, New Zealand and Japan, posing considerable challenges to agricultural production.
Although resistance to Aphanomyces euteiches varies among various pulse varieties, selecting crop varieties with greater resistance is one of the effective ways to manage this disease.
Hosts and symptoms
The host of Aphanomyces euteiches can be annual or perennial crops in the legume family, such as peas, alfalfa, cowpeas and red kidney beans, as well as broad beans and red clover, white clover, etc. Among them, Aphanomyces euteiches f.sp. pisi has a particularly serious impact on pea root rot and is also the type that causes the greatest economic losses. Notably, in North America, different genotypes of A. euteiches displayed host specificity, but this feature was not observed in Europe.
Because A. euteiches is a root infecting pathogen, the main symptoms appear in the root and stem tissues below the soil. Infected roots are often gray, water-soaked, and eventually become soft and appear honey-brown or dark brown. As the infection progresses, root volume and function decrease, leading to a loss of nodules, which ultimately affects water and nutrient uptake.
Infected plants often show symptoms such as yellowing, necrosis of stem segments, stunting and wilting.
Disease cycle
Aphanomyces root rot is a single-cycle disease, with only one infection cycle occurring each growing season. The main source of infection for this pathogen is oospores present in the soil or in the remains of previously infected plants. Oospores germinate in response to chemical signals from the roots of the new host plant.
The infection process usually begins when seedlings emerge from the soil. When the oospores germinate and produce hyphae, they can infect the host directly or indirectly through the root cells. This process poses a potential threat to crop growth, nutrient absorption, and overall yield.
Environmental factorsAphanomyces is a soilborne disease that completes its life cycle within the host roots and surrounding soil. A. euteiches is most active in warm, moist soil conditions. The risk of infection is highest when the host plant is in the seedling stage and the soil temperature is between 22 and 28 degrees Celsius. Poor waterlogging in the soil increases the risk of infection because it promotes the movement of swimming spores.
Management methods
One of the most effective management techniques for farmers is to select disease-resistant varieties. Resistant varieties have been found in alfalfa, beans, peas, and red clover. Although some progress has been made in breeding disease-resistant legumes, it is challenging to meet consumer demands at the same time. Additionally, good soil drainage and soil testing are effective measures to avoid areas of high disease incidence.
Studies have shown that the presence of significant mycorrhizal development in plants infected with A. euteiches can reduce the impact of root rot.
History and Importance
Aphanomyces euteiches was first described by Drehessler in 1925 as the causative agent of pea root rot. At the time, the disease was causing widespread concern in Wisconsin and the Midwestern United States. As the disease spread, the affected area gradually expanded to Europe, Australia and New Zealand.
Especially in pea-growing areas, A. euteiches can cause economic losses of up to 10%. The disease poses a threat to agricultural production and the local economy that cannot be underestimated, especially as local processing factories have chosen to relocate due to the disease. Research shows that modern pea and alfalfa varieties that have been bred for disease resistance have significantly improved resistance to diseases, making sustainable agriculture possible.
So, in the face of a changing climate and disease environment, how should farmers choose the most suitable bean varieties to deal with the infestation of Aphanomyces euteiches?
