BASF’s two new potato blight fungicides based on ametoctradin for the UK market

Potato growers in the UK have two new fungicide options to use in their blight control programmes this year, both with the advantage of containing a new active ingredient from a totally new class of chemistry. Initium, as well as demonstrating foliar and tuber blight activity also has top class rainfastness.

Rob Storer, Potato Product Manager for BASF, explains that Initium is the trade-mark of a new active ingredient with the common chemical name of ametoctradin. “Initium is a highly effective protectant fungicide, showing premium preventative action against potato late blight. It has been coformulated with two other blight fungicides: Resplend contains ametoctradin plus dimethomorph and Decabane contains ametoctradin plus mancozeb. Developing coformulations with complementary active ingredients with different modes of action will enhance the products’ anti-resistance position. In addition Initium is from a totally new class of chemistry, the pyrimidylamines, which has no cross-resistance to any existing fungicides. Both Resplend and Decabane will be important new tools in the fight against both foliar and tuber blight as well as in resistance management.”

BASF researcher Dr. Kristin Klappach from BASF describes the discovery process for Initium and how its detailed mode of action was established.  "Discovery of a novel crop protection compound such as Initium has benefited from new advanced techniques in which activity of the molecule in question can be predicted.  Once the molecule’s effects are known, we can move towards optimising its activity in a straight forward way. These optimisation techniques can help to understand structural features and synthetic approaches.”

Kristin also reviewed research into the mode of action of Initium. “Initium cuts the energy flow of the fungus by inhibiting mitochondrial respiration (Complex III) at an unknown binding site within the cell. It shows no cross resistance to QoI chemistry as it works at a different site.  We have also investigated its activity on zoospores, the causal agents of tuber blight in potatoes, and laboratory work clearly shows that it causes zoospores to burst within seconds of application and at very low concentrations. It also controls the infectious stages of the blight fungus and other oomycete pathogens.”

"We have found that Initium forms a stable layer on the leaf surface, providing a protective shield through adsorption on the wax layer and it can be redistributed on leaves under the influence of moisture”, reports Dr. Klappach.

She also reports on the favourable regulatory profile. “Based on extensive studies, we have found that Initium is safe to humans, animals and the environment and displays an excellent regulatory profile with favourable toxicological and eco-toxicological properties, resulting in a good consumer and operator safety situation.”

Phil Brown, Agronomy Manager for BASF, in the UK shows where Resplend and Decabane fit into a programme and how they perform against the other blight fungicides on the market.

"We know that Initium prevents disease by inhibiting the infectious stages of the pathogen, through preventing zoospore formation and release and through direct effects on the germination and mobility of sporangia.  When combined with dimethomorph in Resplend we have a product that offers protectant, locally systemic and translaminar activity with options for use at rapid canopy, stable canopy and senescence.  It is a mancozeb-free option which may appeal to some sectors of the industry. It has demonstrated in trials that it can stack up well against any of the key blight fungicides in terms of both foliar and importantly tuber blight. It also has fantastic rainfastness, looking to be one of, if not, the best in trials work.”

Decabane has also performed well as a protectant fungicide, as it contains two top protectant actives. It has an important place in the blight programme during stable canopy. Both products can be applied at 7 to 10 day intervals and ametoctradin can be applied up to 4 times in any one crop. Both products will be important when it comes to resistance management, says Phil.

Peter Clare, MD of distributor Environmental Crop Management Ltd., had the opportunity to use Resplend in his blight programmes last year. “We offer potato growers prescriptive agronomy based on local weather conditions and blight risk. Rainfall is high in the North West and can make tight spray intervals difficult. Consequently we have a history of high blight risk in the region. We have also had to contend with A1 and A2 blight for over 15 years and phenylamide resistance is common. We had the opportunity to try out Resplend last year and we decided to test it from the middle of the programme onwards, due to its strength on tuber blight, its curative activity on late infections and its impressive rainfastness.  As far as we were concerned Resplend worked well controlling several late infections and farmers have reported that their potatoes stored very well after two treatments at the end of the programme.”

Peter says that Resplend allows us to attack the tuber blight part of the blight life cycle, whilst maintaining the protection of the haulm, up until now an option not available from one product.

Product Profiles

Resplend contains 300 g/litre ametoctradin and 225 g/litre dimethomorph and is formulated as a suspension concentrate. It is recommended at a dose rate of 0.8 l/ha, delivering 240 gms ametoctradin per hectare and 180 gms of dimethomorph per hectare, in 200 to 500 litres of water. It is applied from early leaf extension to start of leaf senescence at 7 to 10 day intervals. Up to 4 applications per crop can be made. Resplend is rainfast within 1 hour and it is not subject to a LERAP. It is packed in the new 5 litre Eco Pack.

Decabane contains 80 g/kg ametoctradin and 480 g/kg mancozeb and is formulated as a Water Dispersible Granule. It is recommended at a dose rate of 2.5 kg/ha, delivering 200 gms ametoctradin per hectare and 1200 gms of mancozeb per hectare, in 200 to 500 litres of water. It is applied from early leaf extension to start of leaf senescence at 7 to 10 day intervals. Up to 4 applications per crop can be made. Decabane is rainfast within 1 hour and it is subject to a category B LERAP. It is packed in a 10 kg pack.