15 September 1995

Potato cracking common

Root crop growers should welcome recent rains. But the drought has left a legacy of problems in the potato crop, and prospects for beet remain in the balance. Robert Harris and Andrew Blake report

POTATOES have suffered badly in some areas, with small tubers, cracking and chitting common. Unirrigated crops are worst affected but irrigated fields should be checked, too, say specialists.

Scottish ware crops have been badly hit. Only 20% of the area is irrigated. "It has been dry, dry, dry, followed by an awful lot of rain," says Perth-based PotatoCare regional manager David Webster.

"Irrigated crops look very good. Many will produce 24-25t/acre. But some unirrigated ones are an absolute disaster. There are a lot of very small tubers and 9-10t/acre yields will be common."

Cracking is serious in some crops, he notes. Piper are especially bad and Record "terrible". Squire and Wilja are also affected.

"Any crops with a bit of green haulm experienced a sudden upsurge of water. In some cases 75% of tubers are split." Top markets are out – growers could face cuts of £100/t or more to processing destinations, says Mr Webster.

Crops setting skins are at risk and need desiccating quickly, he warns. "We have four acid sprayers on hand – we could do with 24 to keep up with demand."

Beware of storing cracked crops lifted in cold, wet conditions, he warns. "This predisposes tubers to gangrene and other diseases. If growers can lift dry and they have cold stores it wont be so bad. But badly split crops should be moved pretty quickly."

In Yorks, Beverley-based ADAS agronomist Brendan OConnor echoes those views. Well-irrigated crops are in good condition, yielding up to 74t/ha (30t/acre) on best land. But senescing crops could crack. Some unwatered sand land is giving only 12.5t/ha (5t/acre). "Anyone who planted early into moisture is getting three times that," he says. "But growers should burn off quickly."

Shropshire-based ADAS agronomist Denis Buckley reckons yields will be 25% lower in unwatered crops compared with last year. "We are looking at 8-12 t/acre. People wont be making a fortune."

Again, cracking is a "serious risk". Wetter soils have reduced mechanical damage seen in earlier liftings but other problems remain.

"Dry matters are very high, so tubers will be prone to bruising, particularly in cooler weather. Growers should not leave crops, even irrigated ones, to bulk up for evermore. Go for the quality you have now, and not the yield you might have later on," he advises.

The PMBs Rob Burrow warns that even irrigated crops could crack. "Many irrigation systems only kept pace with evaporation and crops remained static. Where there is enough growth left some growers will be able to leave them to bulk. This will probably outweigh any secondary growth." But where skins are setting, growers should consider burning off.

Nick Turnbull, of Lincs firm Branston Potatoes, remains optimistic. "Most growers irrigate here and many main crops are still growing."

High dry matter potatoes will need careful handling to avoid bruising, especially as temperatures drop, advisers warn. And cracked tubers are common in droughty crops soaking up water from recent downpours.