Saskatchewan Pulse Growers, in collaboration with Saskatchewan Ministry of Agriculture, Alberta Pulse Growers, Manitoba Pulse Growers Association, and the Crop Development Centre at the University of Saskatchewan have prepared this need-to-know handout for growers related to root rot in peas and lentils.
Combatting Root Rot in the 2015 Crop Year
"Prevention is the only solution for root rot" Read more from SPG Agrologist Sherrilyn Phelps
It was a devastating June and July for some pea and lentil growers in Saskatchewan as they watched their fields turn yellow while nearby fields did not. For some growers it was patches in the field related to water runs or low areas, and for others it was entire fields. Investigations of these fields revealed a root rot issue across the prairies. The wet, cool spring combined with the presence of the pathogens from shortened rotations or previous crop history of peas or lentils, was the common denominator in these fields. Heavier textured soils and low nutrient status also played a role in some fields.Unfortunately once root rot has set in, there is nothing that can be done. The organisms are soil borne and infect the root of the plant at any time during its growth. Seed treatments can help during the first three weeks of growth but once they wear off there is no longer protection. Foliar fungicides do not penetrate into the roots and therefore are not effective. Infection at the seedling stage can result in poor root growth, and a reduction in nodulation and nitrogen fixation. This leads to yellowing of the plant and stunted growth.
Root rot can be caused by various fungal and fungus-like organisms such as Fusarium, Rhizoctonia, Pythium, and Aphanomyces species. In fact, more than one organism may be present which makes the identification of the main pathogen difficult. Samples from Saskatchewan fields this year have identified Fusarium and Aphanomyces as the main culprits. Aphanomyces euteiches is the root rot pathogen that has been identified in Saskatchewan. Unfortunately it is also the most problematic, as it remains in the soil for many years and there are no fungicides effective against it. There is a need to start thinking about next year’s crop. It is all about prevention at this point and there are a few factors to consider. First and foremost is the environment. Under wet conditions peas and lentils become stressed which makes them more prone to infection. Wet conditions are also needed for the fungal organisms to infect the plants. Wet spring conditions increase the risk for crop stress and infection by root rot pathogens.