22 August 1997

Mix lifts numbers

A MIX of iprodione (Rovral) and imazalil (Fungazil) fungicides has more effect on tuber numbers than either seed size or spacing.

That is the finding from research which aims to maximise tuber numbers to speed the multiplication of new varieties.

"The chemical treatment costs £5-£8/t and is far more efficient at maximising the multiplication of seed than increased seeding rate," said the SACs Eric Anderson.

A 0.5m test dig at the open day produced 51 tubers, with 43 passing over a 30mm riddle, where the fungicide mix was applied to small (33-45mm) seed at 14cm spacing. An identical plot except for fungicide yielded only 34 tubers.

At closer spacing of 10cm, the fungicide-treated plot yielded 53 tubers with 39 passing over a 30mm riddle. The untreated plot gave only 38 tubers in total. &#42