VIDEO: Crop Watch – T3 fungicide dilemma

Recent rainfall could have increased the need for a T3 fungicide, particularly in quality wheats, according to our Crop Watch agronomists.

Mycotoxin risk was now the top priority and each field had to be assessed on an individual basis, said Lincolnshire Farmacy agronomist Philip Vickers. “My thoughts are focused on HGCA guidelines to minimise risk of fusarium in cereals and each field will need to be assessed depending on the variety, weather, growth stage and timing of the last fungicide.”

If a treatment was required, he would be advising his growers to base applications on prothioconazole, metconazole or tebuconazole. “Depending on previous treatments and crop potential a strobilurin may be included. We also need to keep a close eye on mildew levels as levels of mildew on stressed crops have increased rapidly since the rain came.”

In Wiltshire, growers were debating whether T3 applications were necessary, said Dan Dines from Wessex Agronomy Services. “While it is appreciated that the yield response from a T3 may be limited this season, it is important to protect quality on milling and seed crops. So these quality crops will receive a T3, but there may be scope to reduce the dose slightly.”

Spring barley crops had suffered most from the dry spring being particularly short, with low ear numbers, he noted. “But given the value of the crop and the period of unsettled weather, a T2 fungicide will be necessary.”

Broad-leaved weed control had been particularly challenging this spring as dry conditions had toughed weeds, said Mr Dines. “Also, many crops are open so a wet spell could see further weed emergence. This could make a pre-harvest glyphosate particularly useful this year.”

Agrovista agronomist Swaran Bachoo said most oilseed rape crops in Buckinghamshire had finished flowering and many had up to 50 pods on the main raceme. “As long as we get some rain in June, the crops should yield well, but if not we are going to end up with small seed.”

T2 fungicides had been applied to winter wheat and barley, but many growers were unsure if a T3 wheat fungicide was needed, he said. “My advice is to apply the T3 fungicide to the better looking crops, particularly the milling wheats.”

Growers should also try to include a strobilurin element in the fungicide mix as long as two strobilurin applications had not already been made. “This will cover against yellow rust and keep the crop green for longer.”

In Yorkshire, both winter and spring barley crops were thin and open, said Arable Alliance agronomist David Martindale. “But awns are starting to emerge, so growers need to consider applying T2 fungicides to protect recent growth.”

Dry seed-beds meant potato pre-emergence herbicides had been used at lower rates and many crops would now need to be treated with post-emergence contact products such as rimsulfuron, he noted. “Check the latest crop growth stages for post-emergence herbicides as crops are growing rapidly at present.”

Where T3 fungicide applications were justified, Mr Martindale planned to base treatments on triazoles such as prothioconazole, tebuconazole or metconazole. “A strobilurin such as pyraclastrobin will be used to boost brown and yellow rust control, where required.”


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