A novel fungicide with a unique site of action for control of key cereal disease including septoria and rusts is set to hit the UK market in 2020.
Corteva Agriscience’s Inatreq Active (fenpicoxamid) is part of an entirely new chemistry group for cereals fungicides called picolinamides, which have no cross-resistance to other chemistries currently used in cereal crops.
Fenpicoxamid, or UK2A, is secreted by Streptomyces bacteria in the soil and was first discovered in the 1990s. The UK2A enzyme is a natural product with fungicidal properties that is already present in plants, but is it not photostable, meaning it breaks down with light.
Stuart Jackson, field technical manager for Corteva, says the photostable form, Inatreq Active, will deliver 10% better control of septoria than existing SDHIs on the market.
He says: “Inatreq Active gives a new target site which is completely different to anything on the fungicide market.”
With the same mode of action as SDHIs and strobilurins, the quinone inside inhibitor has a unique site of action, meaning where and how it performs is at a different point of the energy process.
Mr Jackson says: “The process of it entering plant tissue happens very quickly, within half an hour. It spreads quickly across the leaf surface on the leaf wax, which acts as a reservoir for the chemical. It will stay there for many weeks in the Inatreq form.”
When the pathogen germinates the active draws it up and enzymes convert it back to UK2A.
“That gives you that protectant activity, and the reservoir in the leaf wax is what gives us the added length of protection we see with Inatreq,” he adds.
Over time, the reservoir in the leaf wax will start to move into the plant tissue, which then converts it back to UK2A. If the fungus has already penetrated leaf tissue, it will draw the UK2A that the plant has converted and effectively kill itself, which is where the curative activity comes in.
The way in which Inatreq has been developed, using the patented formulation technology, IQ4, helps spray to adhere to droplets and stick to the leaf, says Mr Jackson. This improves spread, coverage, penetration and distribution on the leaf and means growers can apply it using lower water volumes at higher forward speeds.
“This allows a lot of flexibility in how the farmer applies it because he will be able to go down to 100l/ha,” says Mr Jackson.
“He can use his low drift nozzles, increase forward speed and reduce volume and he won’t see a drop off in efficacy whereas other products can be compromised when you fiddle with the parameters of application.”
Corteva says this new technology adds to the active’s robust length of protection, showing consistent performance against septoria six weeks after T2 application.
The consistently even leaf coverage seen with Inatreq contributes to its 10% better control of septoria compared to the current range of SDHIs on the market, says Mr Jackson.
He says: “The 97% leaf coverage that Inatreq gives means the chance of a spore landing on untreated leaf is very small. If a product is only covering 75%, there is a greater chance for infection can occur.”
This improved control can be translated to yield return for the grower, adds Mr Jackson.
“In trials, Inatreq has given about a 0.6t/ha yield benefit over the competition. We see a yield benefit going because we keep disease off the flag leaf for longer and increase photosynthetic material.”
In the interest of preserving the mode of action for as long as possible, Corteva will be recommending one application per crop, most likely at T2.
The UK formulation with prothioconazole will be effective against key cereal diseases including septoria, yellow and brown rust, fusarium and rhynchosporium.
The chemistry is showing no cross-resistance to triazoles, strobilurins or SDHIs, according to Mr Jackson, who says: “We can say with confidence there is no cross-resistance with other chemistry groups being used today. It has the same risk as other fungicides to resistance, but it will have a strong resistance management strategy.”
Corteva anticipate the first Inatreq product will be approved in 2020 for all varieties of winter and spring wheat, rye, triticale, durum wheat and spelt, with a following product for barley reaching the market in around two years’ time.
Application timings are from GS30-69 with a flexible water volume of 100-300litres/ha, and a maximum individual dose of 2l/ha, which will deliver 100g/ha of fenpicoxamid.
“Use rate depends on T1 or T2 timings, varietal susceptibility and other factors like weather, but they will typically be 1.25-1.5l/ha,” says Mr Jackson.