Control Root Rot For Good Crops

REGINA - May 13/02 - SNS -- Chickpea and other pulse producers need to take steps to control root rot diseases in their crops in order to achieve the yield potential of their fields, suggests the final report on the project 'Etiology and Integrated Cultural and Chemical Control of Seed Decay, Damping-off and Root Rot of Chickpea'.

"Root rot diseases reduce plant vigour and cause seedling blight in younger plants, so it is especially important to treat chickpea seeds with a registered fungicide," says Dr. Sheau-Fang Hwang, project leader and senior research scientist, Alberta Research Council, Vegreville, Alberta. "Chickpeas planted into warm soils are susceptible to the soil pathogen Rhizoctonia, and those planted into cool soils are susceptible to another soil pathogen, Pythium. No resistant cultivars have been found."

Hwang says surveys of chickpea fields found that the severe damage caused by seedling blight and root rot is also due to the soil fungus Fusarium. Field and greenhouse experiments subsequently found that the fungicide Crown and a few unregistered products improved emergence and yield of chickpea in soil infected by Fusarium or Rhizoctonia. Similar experiments found that the registered fungicide Apron improved emergence and yield of chickpea in Pythium-infested soil.

"Crown received a minor-use registration this spring, which is good news for the control of soil-borne ascochyta and the aforementioned soil-borne root pathogens," says Penny Pearse, plant disease specialist, Saskatchewan Agriculture, Food and Rural Revitalization.

"Producers should be aware of the seed treatments available for control of the specific pathogens: for example, Pythium can only be controlled by Apron, and seed-borne ascochyta can only be controlled by Crown," Pearse continues. "Producers should also be aware of the conditions they are seeding into, and look at previous problems to determine which fungicide to use. If producers are seeding into cool soils and the seed is suspected to be carrying the ascochyta pathogen, they should treat their seed with both Apron and Crown. The department's Crop Protection Guide is always a valuable reference as well."

In the research study, Rhizoctonia was the most virulent of the three soil fungi, so further studies were undertaken to determine its response under a wide range of conditions. Findings included: increased severity with increasing temperatures; high levels of infection reduced nodulation in chickpea; greater seeding depth reduced emergence and survival in infested soil; and delay of seeding into June increased the risk of severe seedling blight.