Rotation in relation to take-all of wheat

Abstract

Using an infertile, sandy, alluvial soil in drums, the effect of five rotations on take-all of wheat (Ophiobolus graminis) was tested. The soil was limed initially. The root-infection rating, total grain weight, and total weight of the wheat plants in each year were recorded. The condition of the roots at harvest time in the final year was significantly worse in the ranunculus and oats-fallow rotations, and possibly worse in the two years' fallow, than in the continuous wheat and two years' grass rotations. In contrast with the condition of the roots, the mean grain yield and mean total weight of the wheat plants in the ranunculus, oats-fallow, and two years' fallow were significantly higher than those obtained in the other two rotations. From the results of this experiment it is evident that the mechanism of control is not, as is commonly suggested, the elimination of the root-rotting organism.