24 March 2000

New granular nematicide suits siltland spuds

Potato growers on siltland in

particular look set to benefit

from new nematicide

Nemathorin. Edward Long

relays their experiences

NEW fosthiazate-based granular nematicide Nemathorin looks set to boost potato productivity on silt soils in particular, thanks to good persistence and activity across a wide range of soil pH.

Maker Zeneca believes it could help halt escalating control problems which have forced many growers into a costly belt-and-braces approach, including autumn Telone (1,3-dichloropropene).

Growers who have tried the product in recent seasons have been impressed. In south Lincs Proctor Brothers of Long Sutton have seen Nemathorin in trials for two years and used it commercially for another two. Last year it protected a quarter of the 160ha (400 acres) of potatoes grown on the farm.

"Nematodes are a constant threat to our crop, which is mainly Cara, Maris Peer and Maris Piper, and after natural selection we are faced with a 100% pallida-based population which is hard to control," says manager, Adrian Howell.

As the population balance shifted to the pallida type aldicarb (Temik) replaced oxamyl (Vydate) and was in turn replaced by ethoprofos (Mocap) five years ago. Now Nemathorin is used.

"We believe it is better than the others and particularly suitable for silt soils. We have seen a reduction in egg numbers where it has been applied. With other granules numbers increase when a potato crop is grown. So Nemathorin offers potential to achieve a good crop and reduce the population at the same time."

That is echoed by Robert Fines, who grows 16ha (40 acres) of Cara for pre-packing on silt soil at Cherry Tree Farm, Gedney Drove End.

"Over the past 10 to 15 years the balance has tipped in favour of pallida, which is harder to control. So despite our efforts our eelworm problem is getting worse," he says.

"Not every field on the farm is infested, but in some it is so bad we have been forced to use Telone for the past three seasons. Last autumn we treated 20 acres. It allows us to lift a good crop but does little to reduce eelworm numbers.

"ADAS suggested Nemathorin was worth trying as it was more effective than either Vydate or Temik, and safer to use. The older granules have performed well here in the past, but after trying Nemathorin on five acres two years ago and on half the crop in 1999 we are now using it on the whole lot this season."

Last year Cara grown in moderately-infested silt soil yielded about 60t/ha (24t/acre). "Nemathorin works well on our soil and guarantees an even crop. As this years Cara is on moderately or severely infested land it will all be treated."

Cambs potato grower Duncan Boughton first saw the new granular nematicide in a trial on his fen skirt soil at Ransom Moor Farm, Doddington near March two years ago. Last year it was used on all his treated land instead of Temik.

"I grow 90ha of potatoes for pre-packing and chipping and have to cope with a variable eelworm problem. For the past 10 years pallida has dominated and because of its long hatching period, the two well-established granular treatments run out of steam before pallida gets going. So we felt something with more persistence was needed."

Potatoes are grown on a one-in-six rotation. The double resistor Sante is used on the worst-infested land and nematicide applied where soil sampling reveals live eggs and cysts.

Nemathorin was tried on a small area of Remarka in 1998. The result encouraged Mr Boughton to use it commercially last season. Despite the high infestation a surprisingly good crop of Sante was harvested, yielding over 50t/ha (20t/acre), with the bonus of reduced nematode numbers at the end of the season. Sampling before planting showed there were 50 eggs/g of soil – after lifting there were 9 eggs/g.

"I now believe Nemathorin used with a resistant variety has the potential to reduce the population and ease the threat to following crops. Depending on the price I will consider using it again this season," Mr Boughton says. &#42

NEMATHORIN

&#8226 First new granular nematicide for over 20 years.

&#8226 Causes rapid paralysis of juveniles preventing root invasion.

&#8226 Boosts yields and limits population build-up.

&#8226 Active through long pallida hatching period.

&#8226 Effective at pH 5.0-8.5.

&#8226 Harmless to non-target organisms.

Robert Fines and son Alan have been impressed with Nemathorins activity on their silt soil at Gedney Drove End, Lincs.

Combined with a resistant variety, Nemathorin offers the scope to cut nematode numbers on skirt fen.