31 May 2002

Perennials – hit them at flag-leaf

DONT forget weed control when applying late flag leaf sprays, says an Essex agronomist.

For some perennial weeds, such as creeping thistle and rosebay willowherb it is the best time and place in the rotation to tackle them, says Harlow Agricultural Merchants Richard Peake.

Both are an increasing problem in the companys south East Anglia trading area largely as a legacy of set-aside.

Controlling them in cereals is crucial, particularly if less competitive crops like peas, beans, sugar beet or potatoes come later in the rotation. "You cannot control creeping thistle in potatoes and it is very expensive to deal with in beet."

Full rate Ally (metsulfuron-methyl), costing about £15/ha (£6/acre), is his advice, applied either in tank mix with flag leaf fungicides subject to compatibility, or as a stand-alone application plus wetter.

Docks, mayweeds, chickweed, charlock and volunteer rape will also be taken out, but to hit cleavers include Starane (fluroxypyr).

Leaving thistle and rosebay-willowherb control for pre-harvest glyphosate is not advisable, he continues. "There is not enough time for it to translocate into the roots before the cereal crop is harvested." &#42