5 July 2002

Potato placing boost

PLACING granular fertiliser beside and beneath potato seed at planting time could boost yield, improve marketable fractions, reduce fertiliser use and protect the environment.

Hydros granule placement kit developed with Kverneland is an extension of the liquid fertiliser system it has offered for over 15 years. It means growers reluctant to switch to liquid can now derive most of the benefits of placement using granular fertiliser.

A standard front hopper is linked to a pneumatic distribution head as used in air seeders, which feeds granular fertiliser into the two hollow placement tines per row mounted on a toolbar between the tractor and the planter.

With fertiliser only being placed where potatoes are planted and not in wheelings, headlands or uncropped corners, total usage can be cut by as much as 15% compared with broadcasting, says area sales manager James East.

Placement also improves crop uptake, boosting yield and improving tuber size fractions, he claims.

Total benefits can amount to over £550/ha, stemming from £9/ha in reduced fertiliser use, £8/ha because no separate broadcasting is required, £120/ha extra yield and up to £432/ha from improved size fractions.

Cost is about £1800 for a two-row toolbar and tines, plus about £2000 for the pneumatic distribution head. &#42

Spraing test hope

FEARS that some potato varieties may be spreading the damaging spraing potato virus without symptoms showing could be allayed with the introduction of a novel test for the damaging disease.

Some varieties, including Marfona, Saxon, Shepody, Rocket and Wilja, can carry the virus without exhibiting symptoms. That could move the virus on to previously clean land without growers knowing.

Now SAC has developed a quick test to spot the presence of the virus. Initially designed to check whether the soil-borne nematodes that can carry the virus are infected, it could also help ensure seed is virus-free, says SAC expert Andy Evans. &#42

Granular placement can boost potato margins by £550/ha, says Hydros James East.

Mustard protection

PLOUGHING down over-wintered mustard or kale residues ahead of potato planting could provide growers with a new way of suppressing increasingly troublesome soil-borne rhizoctonia.

Glucosinolate substances released by brassica plants, which also give culinary mustard its bite, have already been shown to significantly suppress rhizoctonia in lab tests. Now 20m field plots are being evaluated by SAC.

"We chopped the over-wintered cover crops then ploughed them down several weeks ahead of potato planting with relatively little problem," says Elaine Booth. Now assessments of rhizoctonia infection and black scurf in store are planned. &#42