3 August 2001

N fert to boost blight control?

A NEW slow release foliar N fertiliser that may help control potato blight could lift yields by up to 1.6t/ha, according to supplier Agrovista.

The yet to be named product has shown promise in plot trials (see table) and is being field-tested at JSRs Southburn arable farm at Driffield, East Yorks.

Known as EXP 28, it was tank-mixed with Tattoo (propamocarb hydrochloride + mancozeb) blight fungicide and applied three times early this season at 5 litres/ha to 10ha (25 acres).

"Results from EXP 28 in the plot trials showed a reduction in blight and the product is claimed to have adjuvant properties. But its effect on blight could simply be a result of its producing a healthier plant with better disease resistance," says JSR arable technical director Philip Huxtable.

"I am hoping the nitrogen input enhances marketable yield by increasing the proportion of 45-65mm tubers. But I still believe the bulk of nitrogen has to be added in the conventional way."

Mr Huxtable already uses foliar nitrogen when required during early crop growth. However, Agrovista recommends applying EXP 28 earlier than a normal foliar feed because of its slow release properties.

"It will be interesting to see what the final result in terms of yield is to a crop which is given a nitrogen boost when the canopy is being rapidly established." &#42

Agrovista EXP28 plot trial

% blight Marketable infection yield (45-65mm)

Aug 4 Sept 11

Untreated 0 100% 13.0 t/ha

Standard treatment 0 77% 37.9 t/ha

Standard + EXP 28 0 55% 39.5 t/ha

Trial plots were irrigated and the soil inoculated with blight spores.