10 May 1996

Spring frosts blamed for crop loss in Surrey

By Andrew Blake

BIG temperature changes at a critical growth stage are blamed for rare crop symptoms which a Surrey farmer reckons could cost him dearly.

Roger Colebrook of Court Farm, Chaldon first spotted the trouble earlier this spring when his winter cereals and some grasses took on a spiky appearance, with leading shoots apparently sealed inside the top leaf sheaths.

"They looked like spring onions," says Mr Colebrook who estimates about half his 505ha (1250 acres) of arable is affected to varying degrees. Yields on the worst hit areas of the farm could be cut by 25-33%, he estimates.

The land, mainly clay cap running to 200m (650ft) above sea level, has experienced unusual problems in the past including bibionid fly in 1982. "You name it we have had it," comments Mr Colebrook. But pest damage, including gout fly as suggested by the National Institute of Agricultural Botany, has been ruled out this time.

Damage seems contour linked and is worse in the valleys. "We think it is due to the weather." Night temperatures dipping to minus 10C (14F) followed by daytime figures of 10C (50F) on three consecutive days in early March are to blame, he believes.

With symptoms on all the autumn-sown wheat, oats, barley and even some ryegrass and no apparent varietal differences, husbandry is also exonerated, says David Darley, arable specialist with SCATS who has long visited the farm. No spring sprays were used on the crops before the damage was found, he notes.

"I have seen a very small amount of the same thing in Hussar wheat in two fields on a farm near Gatwick."

With the main stems stopped in their tracks, though with the ears still alive and on some plants escaping sideways, Mr Colebrook is trying to stimulate as much secondary growth as possible with a programme of small doses of growth regulator and nitrogen.

The idea is to build good reserves on which the stunted plants can draw, he explains. But he suspects the range of grain sizes that may result will detract from the quality of his crops, several of which are for seed.

Yield potential has already been lost.

An added expense will be a heavier fungicide programme to protect the shorter wheats which will be more septoria-prone, he says.

&#8226 Extremes of temperature blamed.

&#8226 "Spring onion"type symptoms.

&#8226 All cereals and some grasses hit.

&#8226 Up to 33% yield loss expected.

&#8226 Extra expense on fungicides.


Spiky tillers alerted Roger Colebrook (left) and David Darley to potential frost losses at Court Farm, Chaldon, Surrey. Restricted shoots on the more forward plants (inset) are forced out sideways.