19 July 2002

Three-quarters report take-all

THREE -QUARTERS of wheat growers participating in the first national take-all survey report problems with the disease, with one in five rating it as serious.

More than 700 growers took part in this summers National Farm Research Unit survey, sponsored by Monsanto. It showed the average gap between target first and second wheat yields was 0.5t/ha (0.5t/acre), doubling to 1t/ha among growers reporting serious take-all.

But the quarter of growers saying they had no real problems with the disease reported a 1.3t/ha second wheat yield penalty, suggesting infection could be more widespread than realised, says Monsanto seed treatment specialist Geoff Hall.

Failure to use blackened roots as the main way to identify take-all may be to blame. "Nearly 80% of growers continue to use whiteheads as their main way of diagnosing take-all. Yet we know that not all crops suffering from the disease actually show whiteheads, and whiteheads can be symptomatic of other things."

Just under 40% of growers used a take-all fungicide, rising to over 60% of those with serious disease problems. Of the crops treated 84% were second or subsequent wheats, 13% first wheats and 3% barley after wheat.

Although growers considered 26% of their wheat to be at risk from the disease, fungicides were only used on around 10%, says Mr Hall. "This is clearly being seen as an experimental year for treatment."

Fungicide use was almost exactly split between Latitude (silthiofam) and Jockey (fluquinconazole). &#42