For the first time in three years, most oilseed rape crops will benefit from a plant growth regulator fungicide application, according to Dave Ellerton of ProCam.
Growers should be assessing need by measuring the crop’s green area index (GAI), he says.
“The cold winter has taken off a few leaves and pigeons have inflicted further damage, but many crops are still more advanced than they were last year and the year before,” he says.
This will lead to large canopies once the weather warms up. “They need reining back as over-large canopies can lodge and light penetration will be poor, resulting in pod abortion, fewer seeds per pod and less efficient seed filling.”
Growth regulating fungicides work by decreasing crop height and reducing the risk of lodging, explains Dr Ellerton. But he warns growers to use PGR fungicides only when necessary.
“Crops with a GAI of more than one in mid March or over two in April will give an economic response to PGR fungicides of up to 0.5t/ha. But if crops are less advanced, say with a GAI of less than one, they run the risk of yield penalty.”