29 September 2000

Nows the time to make supplier your best friend

Once you have chosen which

varieties to grow, where do

you source your seed and

how should you manage it?

Andrew Blake relays three

specialists advice

GET closer to your potato seed supplier to ensure best results, advises Denis Buckley ADAS national potato specialist.

For mainstream varieties, like Maris Piper and Cara, there should not be much to choose between sources of certified seed, he says.

"Fortunately for the Scottish seed industry they have made great strides in reducing blackleg in stocks of Estima.

"But if you are dealing with blackleg susceptible types, like the chipper Fambo which appears to have real blackleg problems, it might be worth considering the Dutch option."

Hollands generally drier warmer climate is less conducive to blackleg, he explains.

"Virus levels in crops there are sometimes higher, but the certification systems in place keep levels in seed negligible as far as the grower is concerned."

Seed tuber size must be geared to target markets, says Mr Buckley.

"For an early crop you need big seed – there is no way round that. But if you are aiming at a small market with high seed rates using large seed is normally uneconomic. Very small seed can also be useful in reducing levels of silver scurf."

He is keen to dispel the notion that seed grade is linked to amounts of fungal disease present.

"Certification is mainly about viruses and has very little to do with fungal diseases unless they are really bad. If you are using home-saved seed it is absolute madness not to have it virus-tested. But in my opinion you dont need extra tests on certified seed.

"Most people routinely treat for rhizoctonia so black scurf is not the issue it was 10 years ago. And more and more seed is treated with imazalil, or thiabendazole in Holland, against skin spot, dry rot and gangrene.

"Imazalil also gives you a useful reduction in silver scurf. The main thing is to ensure that the imazalil coverage is uniform, which comes back to a personal relationship with your supplier."

The use of fluorescent tracers to check applications is reassuring, he says.

"If you specify liquid Monceren treatment, its orange dye can be a dead give-away as to the uniformity of imazalil coverage through the same sprayer."

On-farm seed chitting in trays is becoming much harder to justify, Mr Buckley believes.

"It is labour intensive and growers are looking for simpler systems. But for late maturing varieties like Piper and Cara in a short growing season on strong land it is still well worthwhile."

On farm chitting is becoming harder to justify, says ADASs

Denis Buckley (inset left), while Bankss Paul Overton (inset right) says ware growers must pay attention to how seed is handled – both at the suppliers, and once on farm.

SEED SOURCING & HANDLING

&#8226 Foster relationship with supplier.

&#8226 Check seed-treatments are uniform.

&#8226 Avoid deterioration after delivery.

&#8226 Go Dutch for blackleg varieties?