The risk of take-all in first and second wheats can be cut significantly by controlling cereal volunteers and grass weeds in break crops, according to experts.
“Just a few volunteer cereal plants or grass weeds in rape stubble can maintain the take-all fungus in the oilseed rape crop,” said Bill Clark from ADAS Boxworth.
“The following wheat will become infected from direct contact between infected and new crop plant roots. First wheats may not show obvious symptoms of take-all but the disease may be present on the root system.”
The disease may be more of a problem in minimal cultivation systems, which have high soil organic matter close to the surface, he noted.
The main grass species that act as a host to the take-all fungus are Yorkshire fog, brome and bent, added Rothansted’s Richard Gutteridge. “…Ryegrass and blackgrass act as a host to a lesser degree.”
The risk of take-all fungus being carried over has been increased by the use of grass cover crops in set-aside, he said.
Mr Gutteridge urged growers to aim for complete control of grasses and volunteer cereals if the following wheat is to achieve its full potential. This can be done by using a combination of herbicides, including a long-lasting soil acting residual (e.g. Kerb (propyzamide)), he said.