12 April 2002

Cranes bill incidence is creeping up

By Andrew Swallow

GROWERS should check crops for the broad-leaved weed cranes bill prior to T1 sprays and consider tank-mixing a suitable sulfonylurea herbicide, says a home counties agronomist.

"It is left behind by the autumn residuals in cereals and oilseed rape and is an increasing problem," says Phillip Styles of Beds-based LW Vass.

He estimates 15% of the combinable crop land in the companys operating area is affected, mostly on lighter soils.

While it is not a highly competitive weed itself, it can cause harvesting difficulties and raise the moisture content of grain at harvest.

"Anything over 15 plants/sq m will cause a yield reduction and considerable inconvenience. Besides, controlling the cranes bill will take-out other weeds too," he says.

Ally (metsulfuron-methyl) or DP928 (metsulfuron-methyl + thifensulfuron-methyl) is his preferred control. "The mix of actives in DP928 is slightly better on larger weeds or if a broader spectrum of control is needed."

Typically about a two-thirds rate of either product, 20g/ha of Ally or 40g/ha of DP928, is adequate. However, if thistles are also present Ally has the advantage and a full 30g/ha is needed.

To avoid making extra spray passes through the crop he suggests tank-mixing with T1 fungicides. "By GS32 the canopy has usually opened up a bit, which gives you a better target and the weed will be actively growing."

Cranes bill is autumn germinating, so the trend to earlier drilling could be another factor behind the weeds increase, according to IACR-Rothamsteds Peter Lutman.

"It is not nearly as competitive as, say, cleavers, but in a wet summer it can keep on growing and climb up with the crop to some extent."

Where that is the case the current rating of the weed (see table) may be a little low, he adds. &#42

Could cranes bill be climbing the weed league table? Phillip Styles is certainly finding it more troublesome.