16 August 2002

Whiteheads are not just due to take-all

FUSARIUM and eyespot may be as much to blame for whiteheads in winter wheat as take-all, suggests seed treatment supplier Monsanto.

Detailed root analyses of 24 crops with marked whitehead problems show average eyespot and fusarium indices of 62 and 78 respectively, on a scale of 1-100, compared with an average of 39 for take-all.

"Our work with growers reporting whitehead problems clearly shows stem and root infections from eyespot and fusarium in particular are responsible for a significant proportion of the seasons symptoms," says the companys Geoff Hall.

Take-all incidence is high, he says, large-scale national split-field studies showing an average take-all index of around 40 in crops receiving basic seed treatment only. But three-quarters of crops with severe take-all also had an eyespot index of over 50 and two thirds had equally serious fusarium root infections, both of which also cause whiteheads, Mr Hall notes.

He urges growers to check for root symptoms to confirm take-all levels, adding that in some instances take-all can be high even when whitehead incidence is low.

In the companys large-scale trials, Latitude has kept take-all indices down to an average of just over 22, compared to 36 with basic seed treatments, he adds.

"But restricting take-all infection will only produce the goods if other damaging diseases like eyespot and fusarium are also controlled, through appropriate T1 spray selection in particular." &#42