NEW TRIAZOLE Proline (prothioconazole) has a role at all three spray timings in wheat, but its key strength is in the T1 spray, agree disease control experts.

Alison Daniels of manufacturer Bayer CropScience says the combination of septoria and stem base disease control makes Proline an obvious choice for the all-important T1 spray.

 “It sets new standards in early septoria control and is better on eyespot than Unix,” says Dr Daniels. “It also has the edge on mildew compared to other triazoles, although for curative situations you may need to add some morpholine or spiroxamine.”

She believes it is also a good T2 fungicide if the programme is well timed. “If the T1 spray has gone wrong and there is a need for curative septoria control, it may struggle. In a difficult situation, epoxiconazole would be better.”

At T3, Proline offers broad-spectrum control of ear diseases, with exceptional suppression of fusarium and mycotoxins, she adds. “Robust rates are important at T3. You need 0.5-0.6 litres/ha at this timing, so spend as much as you can afford.”

The decision on whether to add an eyespot fungicide at T1 has been an annual conundrum for many growers, says Velcourt”s Keith Norman.

“Eyespot is a problem two years out of every five. The difficulty is knowing when the risk is high and whether you are likely to get a cost-effective response from a specific eyespot treatment.”

Proline simplifies the T1 decision process, Mr Norman believes. “As well as taking care of eyespot, it brings stem base fusarium control into the picture. And there is good evidence that it is a major step forwards for this disease.”

Where there is a preceding crop of peas, using the newcomer will bring clear benefits over alternative triazoles, he says. “Peas make fusarium worse. Our trials showed big differences when Proline replaced epoxiconazole in the T1 spray in this situation.”

 Having another triazole option is useful and will be important to growers, especially as strobilurin resistance is widespread, he notes. “The drift in triazole field performance continues and we have to learn how to manage triazoles. A new addition will help to slow down further insensitivity build up.”

 ProCam”s David Ellerton agrees that Proline has a very good disease spectrum. “Getting to know its strengths and weaknesses will help to get the best from it. Eyespot and septoria are problems in most of the popular wheat varieties, and prothioconazole has persistency against both diseases.”

 It also controls mildew, yellow rust, brown rust, stem base fusarium, ear fusarium and sooty mould control, he notes. “The slight chink in its armour is with the rusts, like most triazoles, but you can always solve that with fluoxastrobin.”

 Dr Ellerton sees a place for Proline at T1. “It”s the main timing for early protectant control of septoria, mildew and yellow rust. You can also get control or suppression of eyespot, fusarium and take-all at this stage.”

 On second wheats, he prefers co-formulated product Fandango (prothioconazole + fluoxastrobin). “The fluoxastrobin component brings take-all suppression and adds to the control of the other stem base diseases. So it is a better fit on second wheats and is the main contender for barley.”

He accepts that Proline will also be useful at T2, which is the main timing for yield enhancement and curative foliar disease control. “There are two exceptions to this – in severe curative septoria and brown rust situations there are better choices.”

 There is also a case for Proline at T3, he agrees. “It has activity on the ear diseases and offers the top-up foliar disease control. Again, the co-formulated product has a place, too, especially on milling varieties.”

Despite its other potential timings, he expects the product will have greatest impact at T1: “It”s the control of stem base diseases which will appeal to growers. And it”s where growers will get the most cost benefit from the fungicide.”

fwcropsfwi@rbi.co.uk