15 May 1998

Spray peas early-on

DONT put peas too far down the spray list as you try to clear this springs spraying backlog.

Cleavers, the crops main weed threat, could get beyond the controllable stage, hitting yields, boosting the soil seed bank and hindering harvest progress, warns PGRO trials officer Cathy Knott.

Crops drilled in late March or early April which had residual herbicide applications rained off are at greatest risk. "Cleavers seem to be the main problem and the more advanced ones are pretty large – three or four whorls. Thats getting beyond the stage for Pulsar plus Fortrol and into the timing for Basagran," she notes.

United Oilseeds agronomist Richard Elsdon agrees that it would be unwise to give peas a low spray priority.

"Theres often a very narrow window for post-emergence herbicide treatment. Its wrong to assume the quickly growing crop can compete effectively with weeds. If they get too big the crop is unable to smother them and the result can be dire."

Forward crops will reach the flowering cut-off for herbicide use before the end of the month, warns Bob Mills of Banks Agriculture.

He suggests a Fortrol/Trifolex mix (cyanazine/MCPA + MCPB), both at 2.0 litre/ha, but if cleavers are a problem, use Pulsar (Bentazone + MCPB) at 4.0 litre/ha with 0.4 litre/ha of Fortrol he adds.

Roger Bryan, a member of O & N Management Consultants operating in southern England, advises: "If cleavers are at the cotyledon to one whorl stage the lowest Pulsar plus Fortrol rate of 2.0 and 0.2 litres/ha will do the job. The rate will need winding up to 3.0 and 0.3 or 4.0 and 0.4 litres/ha for bigger cleavers." &#42