TAKE-ALL IN AUTUMN-SOWN WHEAT, BARLEY, TRITICALE AND RYE GROWN WITH HIGH AND LOW INPUTS

Winter cultivars of wheat, barley, triticale and rye were grown under two contrasting husbandry systems (low and high inputs) at two locatio ns (Woburn and Rothamsted) known to be infested with the take-all fung us. The sandy loam at Woburn is less fertile than the silty clay loam at Rothamsted. Root infection in these crops was assessed in spring an d summer. Rye was least infected by the take-all fungus, wheat the mos t infected and barley and triticale had intermediate levels of infecti on. Barley yields were less affected by take-all than those of wheat o r triticale, because barley was at a later growth stage by the time se vere infection occurred. Yields of wheat and barley responded most to the high-input husbandry on the less fertile soil at Woburn. On the ba sis of quantity of grain, triticale would appear to be a good substitu te for wheat on the less fertile soil when inputs are low, but not whe re they are high. At Rothamsted, yields of wheat and triticale were si milar in both input systems. There was no strong support, at either si te, for the contention that triticale could be a useful substitute for barley where low or high inputs are used. A total of 177 isolates of Gaeumannomyces graminis var. tritici (the causal fungus of take-all) w ere obtained from infected roots in these experiments and tested for t heir pathogenicity on wheat and rye seedlings. These tests revealed a range of pathotypes with varying pathogenicities to wheat and rye, but pathogenicities were not correlated with the host plant from which th e fungi were isolated.