26 May 1995

Nematode hot spots warning

APPLYING nematicides on the clod and stone separator could be storing up trouble for the future. That is the uncompromising message from Mary Hancock of Cambridge ADAS.

Although such applications prevent yield loss, they could let nematodes reproduce unchecked. Granules can be left too close to the soil surface, or diluted in too much soil if the machine is worked too deep. Whatever setting is adopted areas between ridges are left untreated. "These can become real hotspots," she warns.

"The result can be much, much higher nematode levels in future, which could be a real problem for growers facing palida. Be warned – applying nematicides on the separator may not give sustainable control even if the granules are applied to the flat in front of the separator," she says.

Where nematode levels are high growers should consider abandoning the separator. "Using a rotavator or vertical band applicator gives the best results."

Check granule spread

If a separator is still used growers should avoid working too deep and check granules are spread evenly through the ridge to the required depth, she advises.

"Separating is a compromise," acknowledges David James of Rhone-Poulenc. Moving the applicator fish-tails as far forward as possible can help, he suggests. Another alternative is to replace the bed-former with a bed-tiller and apply granules through that. "Some people are trying this and it seems to be a good compromise."