Take-all on the increase

Healthy plants (left) contrast with the stunted growth of plants affected by take-all (right).

Take-all is the most serious widespread root disease affecting wheat and barley in Western Australia. It is most common and likely to cause serious yield losses in high- and medium-rainfall zones of the agricultural area, said Agriculture Western Australia's Plant Pathologist Bill MacLeod.

Mr MacLeod said the fungus causing take-all survives over the summer in the roots and crowns of plants infected during the previous growing season.

Connection to limed paddocks

He said farmers should be aware that if they don't look after their farming systems, take-all has the potential to cause increased losses due to disease in limed paddocks.

"Also, if farmers forgo good crop rotation practices and plant cereal on cereal because their wheat crops were hit with frost last year, take-all may well flare up in the second cereal crop, reducing the yield."

As a rule of thumb, if pH levels are below 4.5 (calcium chloride), farmers can expect the disease to be present but not necessarily visible, whereas if the soil pH is better than 4.5, take-all is more likely to become a problem.

"When farmers are planning to lime their paddocks they also need to look at their overall farming system. This means keeping the grass level in their break-crop phase (i.e. legumes, canola, medic and sub-clover pasture) low.

"Eliminating grasses in break pastures in winter will have a significant effect on the reduction of take-all disease. One year of grass-free break pasture will decrease the disease from very visible damage in the crop to virtually nothing. It is very responsive and you can reduce it very quickly," said Mr MacLeod.

Contact: Ms Dominie Wright 08 9368 3721