Take-all is a disease that is becoming a major challenge on Irish cereal farms. Black patches in stubble can be an indicator of the problem’s existence.
However, Seedtech’s Tim O’Donovan outlined a much more definitive test for the disease at the company’s recent trials event in Co. Waterford.
All that is required is sample of fresh soil, taken from a field that has just been combined, a single cereal seed and a plastic tea or coffee cup.
Testing for take-all
Instructions follow – fill the cup with soil, place the seed in the soil, bring the cup indoors and leave on a warm window ledge.
Inspect the cup 10 days later, by which time the seed will have germinated. It is then a case of gently peeling the plastic away from the soil mass. This will expose the full root mat that has developed within the cup.
If the roots are white, then take-all is not an issue. However, if the root mat is coloured black, one is then left to mull over the implications of the well-hackneyed phrase, ‘Houston, we have a problem’.
Take-all is an important disease of winter wheat, especially as control with fungicides or varietal resistance is extremely limited. The disease is also moderately important in winter barley. Spring sown cereals are not as badly affected.
The fungus is now widespread throughout the UK and Ireland. It acts to reduce yield and grain quality.
Estimates suggest the disease affects half of UK wheat crops, with average yield losses of 5–20% resulting. However, more than half of the crop can be lost when disease is severe.
Take-all causes most damage on light soils where the fungus spreads more easily and the loss of active roots has a large effect on water and nutrient uptake.
Poor drainage and nutrient status also encourage the disease. The weather also has a large influence on the impact of take-all. Dry conditions during grain filling exacerbate the damaging effects of the disease on root function.
Northern Ireland
Experience in Northern Ireland would indicate that take-all is acting in an almost sub-clinical manner on many cereal farms.
Leigh McClean is a crops development advisor with the College of Agriculture, Food and Rural Enterprise
He commented: “Some winter barley yields were disappointing last year, despite crops looking well in the fields.
“Growers were attributing this fall-off in final yields to Barley Yellow Dwarf Virus. Weather conditions for aphids, the vector of the virus, had been very suitable the previous autumn.
“Sub clinical take-all may also be an issue in winter barley. These are crops that are mainly grown as a second cereal within an arable rotation. Carry over issues relating to take-all can be an issue in this context,” McClean added.