Communication key to meeting market specs

28 September 2001

Communication key to meeting market specs

By Andrew Swallow

POTATO growers are having to produce crops to tighter market specifications than ever before and that means seed management must be first rate.

Gone are the days of growing a general crop and grading to meet a target market, says Cambridge University Farms Eric Allen. Today, to be competitive, growers must start managing the crop for the target market from when the mother tuber is initiated.

For those growing their own seed that is their own responsibility but for the majority that means talking to seed suppliers about target market and seed management from a very early stage.

"The key message is a very old one. You have got to communicate with your seed supplier," he says.

Early planted seed crops initiate tubers earlier, producing seed which breaks dormancy relatively early for the variety, he explains. The conditions under which the seed breaks dormancy are crucial to controlling sprout number and apical dominance.

"If it is warm enough for sprouts to grow rapidly when the seed breaks dormancy, say 8-10C, then you will get apical dominance. But every variety is unique – some take just a few weeks to break dormancy, others months. It can be September or February-March."

Once that apical dominance is established cooling the seed to retard sprout growth will not suppress the apical dominance.

"You cannot break apical dominance without breaking the sprouts and that will introduce more variation in the field and the risk of disease."

Crops grown from apically dominant seed set tubers earlier, but fewer of them. Hence ware growers aiming for early markets, especially early baker markets, should manage seed, or request that it is managed, so that it is apically dominant.

However, apical dominance is the last thing you want for punnet and seed crops or shy varieties, he stresses.

"For punnets you want a large number of stems to produce lots of tubers. Similarly for varieties like Hermes that set few tubers you absolutely do not want apical dominance."

Keeping seed cold, 4C maximum, during dormancy break avoids apical dominance and helps produce many sprouts/tuber. Once dormancy has been broken storage temperatures may be raised to 10-12C to advance sprout growth a few weeks prior to planting.

Crops from sprouted seed emerge faster and tend to senesce earlier. The BPCs Rob Clayton stresses light must be used to keep sprouts short and strong so they are not lost prior to planting.

"If you dont, sprouts will break off and you get lots of variability in the field. If you cant manage it then really you should forget about these early markets."

Controlling dormancy break and sprout growth means refrigerated storage of seed is a must, maintains Mr Allen.

"Look for a seed supplier with a fridge store. If ambient air stores are the only ones available there is a danger seed will sprout inadvertently."

Sprout development

Mr Clayton agrees refrigeration is preferable, but warns seed must never be put in a store where CIPC sprout suppressant has ever been used. If a fungicidal seed treatment is to be used it should be applied prior to any sprout development.

"The label recommendations are there for a good reason. Also, consider targeting fungicide use. If there is no seed borne disease risk why put it on? Why expose the crop to that phytoxic risk?"

Professional seed inspection services, costing £35-£40 for a wash and visual inspection plus £20-£25 for an eye-plug test for rhizoctonia, skin spot or silver scurf, are cheap relative to the cost of the seed, he says.

"Knowing the health status of the seed is essential. There are many tests available and results may be provided as an additional service by the supplier."

When to take delivery of the seed depends on who is best equipped to handle the management of it. "Even just in time delivery is an option. It all comes down to your confidence in your seed supplier."

But that does not mean just in time ordering, he adds. "Late orders can lead to rushed grading and handling. The key message is get seed ordered early." &#42


&#8226 Assess own facilities against suppliers.

&#8226 Light vital if chitting.

&#8226 Refrigeration essential.

&#8226 Know variety dormancy differences.

&#8226 Manage seed for target ware market.

&#8226 Order early with detailed spec.

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