22 December 2000

Let labs test seed for disease before saving

GROWERS planning to farm save spring barley seed should have it disease tested even though less than 1% of samples checked so far have produced a positive result, says NIAB.

No leaf stripe and a negligible number of loose smut infections have been found in farm samples, but growers would be taking an unreasonable risk by sowing undressed, untested seed, says plant pathologist Jane Thomas.

"We have seen a few samples with significant infections. They are not serious in themselves, but do merit a seed treatment."

Typically, yield loss is only comparable to the proportion of infected seed sown. However, growers sowing infected seed risk infecting neighbouring crops with the disease and an escalation of the problem year on year.

NIABs Labtest service on leaf stripe, loose smut, net blotch, germination and thousand grain weight costs £100/sample. At that it may be cheaper for growers to treat small seed lots without testing. But which treatment is chosen needs care as some products do not control loose smut, she warns.

"For milling and malting markets varietal purity is also important." A combined visual and electrophoresis varietal purity test to 98% is £45.

Spring wheats seed-borne disease risk relates to time of sowing. Early sowing into a cold seed-bed favours both michrodochium and bunt development, but risks are less with later sowings, she says.

However, bunt is not a disease to take risks with, since it can result in complete crop loss. "If the level of infection is bad it renders the crop completely unsaleable."

Germination tests show most spring cereal seed lots should grow well next spring, says colleague Steve Jones. But if growers have any doubt about the condition of seed, especially if storage has not been ideal, a test prior to drilling is advised. A germination test costs £27/sample, and a vigour test £45.

SAVINGSPRINGCEREALS

&#8226 Disease test seed?

&#8226 Use seed treatment if necessary.

&#8226 Germination test if unsure.

&#8226 Treat small lots anyway.