An association between lime application and the incidence of take-all symptoms on wheat on an acid soil in north-eastern Victoria

The effects of lime, deep ripping and fertiliser treatments on the occurrence of take-all symptoms in wheat in north-eastern Victoria, was studied in a field experiment. Large wheat grain yield increases had previously been obtained at this site from both liming and deep ripping of the soil. Symptoms typical of take-all (Gaeumannomyces grarninis var. tritici) were observed on plants in all plots in the 1985 season. There were no differences in numbers of dead heads in wheat grown on unlimed soil and where the soil was treated with 0.5 and 1.0 t lime ha-l. However, 20 and 30% of the heads were dead heads where the soil was treated with 2.5 and 5.0 t lime ha-1 respectively. Plants with dead heads were severely lesioned. Where disease was most severe, 1000-grain weight was reduced. Although liming the soil increased the damage by Gaeumannomyces graminis var. tritici, and perhaps other pathogens, the overall grain yields were not reduced because of the countering effect of lime promoting yield. Lime also altered the composition of grasses in pasture plots, resulting in more brome grass and barley grass. The control of take-all by crop rotations and controlling grassy weeds in pasture could be a necessary adjunct to liming if maximum yield benefits are to be obtained.