Best timing for Electis from start of tuber initiation onwards

Gowan Comércio, the new owners of the active ingredient zoxamide, are advising potato growers that the best time to start using their protectant fungicide Electis is from the beginning of tuber initiation onwards.

"The best timing for Electis is to do with its unique way of working and the fact that once tubers start to form they are at risk from tuber blight. Electis is protectant in nature, binding strongly to the leaf surface and epidermis, making it highly rainfast and resistant to run off due to either rain or irrigation. But its optimum timing is also to do with the unique way that it affects zoospores, the causal agents of tuber blight," explains John Edmonds, European Technical Manager for Gowan Comércio.

John explains that spores are produced in sporangia, developing on the leaves from foliar infections. "Each infected plant can release millions of zoospores when the conditions are right. Once released or washed down by rainsplash, zoospores fall to the ground and into the soil, causing infection by germinating near to the tuber and entering access points such as buds, lenticels and wounds. The fungus then spreads and starts to breaks down cellular tissue. You only need a few zoospores to reach potato tubers to suffer significant and damaging blight infections. Symptoms are usually seen one month after lifting, but the disease must be prevented in the field, well before it gets into store."

"There are only a few blight fungicides that have proven zoospore activity, but they need to be used in a specific way according to how they work. Zoxamide in Electis for example stops zoospore formation and release, resulting in the production of non-motile spores, incapable of infecting tubers. By reducing the zoospore loading as early as possible from when tubers are initiated onwards, Electis can optimize the activity of other fungicides that have more direct zoospore activity," says John.

John explains that other blight fungicides such as fluazinam, cyazofamid or fluopicolide + propamocarb act directly on zoospores once they are released, preventing them from reaching tubers. Such products would be beneficial once Electis has been applied, he says.

According to John, growers should not rely on just foliar blight control to prevent tuber blight, particularly when blight pressure is high. "Crop foliage must be thoroughly protected by robust blight fungicides that also have proven zoospore activity. This is particularly so as tubers are vulnerable from tuber initiation onwards. Tuber initiation can be defined as when the tuber is twice the diameter of the attached stolon and in most varieties starts around three weeks after emergence."

"With the high blight pressure we seem to experience every year these days, best practise is to keep spray intervals tight right up to and beyond desiccation. Electis can be used up to 10 times in the season, which is important when applications are being made at closer intervals. This also gives growers ultimate flexibility as to how they integrate this fungicide into their programmes for effective foliar and tuber blight control and as a resistance management strategy."

For further information, please contact John Edmonds, European Technical Manager for Gowan Comércio on 01223 506 606 or 07764 268 199 (mobile).

®Electis contains 8.3% w/w zoxium (zoxamide) and 66.7% w/w mancozeb, formulated as a WDG. It is recommended on all varieties of potatoes at spray intervals of 7 to 14 days. It has a dose rate of 1.8 kg/ha in 200-600 litres of water per hectare. It has a maximum number of treatments of 10 per crop and a harvest interval of 7 days. It is packed in a 3-ha pack (5.4 kg).

Gowan Ltd is a family-owned international company with its Headquarters in Arizona, USA. Founded in 1963 it has a turnover of $330 million and employs over 625 employees. Its business strategy is to target opportunities to acquire product lines from larger companies and revitalise them. Although the majority of Gowan’s current business is in the USA, the company is expanding internationally, particularly into Europe. It now has European interest in Spain, Italy, Portugal, France and the UK.