Assessing take-all risk in second wheat using the Predicta B test

Abstract

Soil samples were taken after the first wheat harvest in 2007 from three experiment sites at two locations. Joint replicated soil seedling bioassays and take-all DNA quantification measurement were done on a total of 40 soil samples. A strong positive correlation was found between the take-all DNA in the soil and in two of the three sites. These two sites had very different soil types. At the third site there was also a positive correlation between the two variables but this was weaker.

Two of the three sites were sown to a second winter wheat in October 2007 and the severity of take-all was assessed in July 2008 on those plots where the take-all DNA and the take-all infectivity of the soil had been measured. On both occasions, there was a strong positive correlation between the infectivity of the soil, measured prior to sowing the crop, and the percentage of plants in the subsequent crop showing moderate or severe disease symptoms. Take-all DNA in the soil, measured prior to sowing the crop, also showed a strong positive correlation with the percentage of plants showing moderate or severe symptoms of the disease in one experiment but the positive correlation was weaker in the second experiment.