Tackling blight with the right product at the right time
Late blight in potatoes requires a full protective programme, starting at the rosette stage and running right through to harvest. UK growers have a wide choice of effective fungicides and need to put together the right programme using the right products at the right time, says Gowan Commercio.
Technical Manager Robert Plaice reports that the use of fungicides in a proactive and flexible way is the key to success now with more virulent blight in the UK. “Unlike other European countries, the UK blight population is dominated by two particularly aggressive strains - 6A1 and 13A2. These strains are characterised by their ability to thrive at lower temperatures,and by producing more spores through shorter lifecycles. At most stages in the blight life cycle, fungicides should be deployed in a protective manner in order to stop infection.”
“Studying the detailed activity of fungicides, we know that both active ingredients in Electis, zoxium and mancozeb have specific properties helping to control the blight population. Mancozeb will prevent spore germination on the leaf surface and zoxium acts on cell division of the fungus, preventing formation of the next nucleus, stopping the germ tube elongation of spores and preventing infection. It does so as the germ tube grows along the leaf surface or down through the waxy leaf cuticle into the leaf. This anti-sporulant activity is in addition to zoxium’s unique effect on zoospore production and motility, the agent for tuber blight,” explains Rob.
“It is important to drill down into the intricacies of how fungicides work in order to position them correctly within the ten to twelve fungicide sprays within the programme. Each fungicide has differences in the way it protects the plant and its activity on Early or Late Blight. Looking at Electis, it will be best positioned in the second half of the spray programme after full canopy growth and before the last two sprays generally consisting of either Shirlan (fluazinam) or Ranman (cyazofamid).”
“Not all blight fungicides have proven zoospore activity and those that do work differently. Zoxium in Electis stops zoospores being formed and released, resulting in non-viable spores, incapable of infecting tubers.”
“Its use reduces zoospore loading, so optimizing the activity of other fungicides that are active on motile zoospores Fluazinam and cyazofamid act on zoospores once they are released, preventing them from reaching tubers. So these products are more beneficial and compliment Electis at the end of the programme.”
Rob goes on to say that Electis is a robust and effective fungicide containing two complementary and very effective active ingredients. “It is extremely rainfast and has a strong anti-resistance position.There has been no reported resistance to mancozeb after more than 40 years of commercial use. Zoxium also works on a site within the nucleus of the fungal cell where very few other fungicides work, so adds another element of resistance management.”
