Sound advice to beat ear blight
FUSARIUM ear blight is a serious disease, yet the risk of trouble can be reduced by choice of variety, chemicals and ploughing.
The disease has been particularly severe for four seasons. After a worrying build up in 1997, the worst year for over a decade, it reached epidemic proportions in 1998 with 60% of fields infected.
"That was the worst year ever for ear blight, but it did not go away because in both 1999 and last year around 40% of the crop was infected," says Pete Jenkinson of Harper Adams University College.
"As well as knocking yields, the fungus is responsible for mycotoxins which can contaminate grain."
A wheat crop with a yield potential of 8t/ha with 10% of its spikelets infected will lose 0.5t/ha. But potentially more serious is mycotoxin contamination that even at low levels can jeopardise export opportunities.
Four organisms can cause ear blight. The most common, Microdochium nivale, does not produce mycotoxins.
The second most important, Fusarium culmorum, can produce toxins. The risk can be reduced by avoiding maize in the rotation and ploughing to bury trash, an important source of infection. Tall strawed varieties are more resistant to blight than shorter types, but using pgrs does not change the picture.
"Prevention is better than cure," Dr Jenkinson advises. "A mixture of Amistar and either Folicur or Caramba at between a third and half rate should be applied as close to flowering as possible." *