Time to move onto Electis now

UK - June 08, 2007

As crops reach stable canopy stage and the blight pressure mounts across the country, Dow AgroSciences is advising potato growers that they should be incorporating strong protectant fungicides with known zoospore and hence tuber blight activity into their blight programmes.

"From mid-season onwards as soon as tubers are being formed, blight sprays need to provide proven protection against tuber blight and foliar blight.  Zoospores are the causal agents of tuber blight and these motile spores can be produced from now on, usually when the temperatures get below 15ºC.  But not all fungicides have proven activity on zoospores.  Zoxium in Electis stops their formation and release.  Other fungicides act on zoospores once they are released," comments Andy Leader, Principal Biologist for Dow AgroSciences.

"Considering the specific modes of action on zoospores, it is advisable to use the strong protectant Electis early on in the programme, the objective being to reduce the zoospore population.  By reducing the zoospore load as early as possible after tuber initiation Electis will optimize the activity of fungicides with direct zoospore activity.  Electis is recommended from stable canopy or tuber initiation onwards to stop zoospore formation and control foliar blight. Ten applications of Electis can be made to any one crop and there are no restrictions on applications in blocks or sequences.  This means foliar blight and tuber blight control programmes can be built around Electis that are both effective and simple," says Andy.

"The use of Electis with other zoospore-active fungicides in a programme provides an all-embracing approach against foliar, stem and tuber blight.  This approach is frequently validated in trials when Electis, applied from stable canopy onwards and then alternated with a fungicide with additional zoospore activity such as Ranman TP (cyazofamid) up until desiccation gives excellent control of both foliar and tuber blight compared to similar programmes without Electis," explains Mr. Leader.

"Electis is a strong and effective protectant fungicide, outperforming fluazinam and cymoxanil plus mancozeb in trials over many years and it is categorised as one of the top foliar blight fungicides by a panel of European industry experts.  It is a highly suitable product to integrate into any blight programme, appearing to enhance the programme," he comments.

According to Andy, the choice of blight fungicide at this point in the programme makes a crucial difference to the successful prevention of foliar and tuber blight and the production of a high yielding and quality crop.  "You cannot rely entirely on foliar blight control to prevent tuber blight.  Growers must protect the foliage from an early stage by using robust foliar blight fungicides with proven zoospore activity at appropriately tight intervals and maintaining this protection at and beyond desiccation.  You only need a few zoospores to be formed and released into the soil for potato tubers to suffer significant and damaging blight infections.  Last year there were few Smith periods and very little blight earlier on, but you still needed a robust programme to keep zoospore inoculum levels low and disease control levels high."

Mr. Leader points out that as there are a number of blight fungicides with the same mode of action another important consideration of a blight spray at this place in the programme is resistance management.
 "Electis contains zoxium which has a different mode of action, distinct from other potato blight products and mancozeb, which is a tried and tested highly effective protectant fungicide with multi-site activity.  Both the actives in Electis complement each other in terms of the way they work.  Because the Electis label allows up to ten sprays in any one crop and no restrictions on sequencing or blocks, it means that growers have ultimate flexibility as to where, when and how they integrate this fungicide in their programmes from stable canopy onwards.  This is not the case for many other fungicides, including the newer ones and growers need to make sure that they adhere to the label and FRAC guidelines for these other products, particularly when it comes to number of sprays and alternating products with different modes of action," concludes Andy.