Crop Watch: Pest and disease risk rises

Orange wheat blossom midge monitoring and outstanding flag leaf sprays are top of the agenda for our Crop Watch agronomists this week.

In Hampshire, winter wheat was at GS53 with ears staring to emerge, said Agrovista agronomist Swaran Bachoo. “Any flag leaf sprays that have not been carried out should be completed soon, as the risk of septoria has increased considerably.”

Top leaves were clean, but septoria was sitting in the bottom of the canopy. “It won’t take long for it travel up to the flag leaf,” he said. Yellow rust had been noticed in a crop of Oakley that was sprayed with a robust T1 fungicide three weeks ago.

Where there had been significant rain, orange blossom midge adults could start flying onto emerging wheat ears, he said. “Where there is a history of the pest, two pheromone traps should be laid per field and if 30 adults per trap are caught over two to three days, it would be advisable to carry out in-field monitoring.”

T0, T1 and T2 fungicides had been applied as planned in Yorkshire, said Arable Alliance agronomist David Martindale. “As a result, crops are very clean, but yellow rust has established itself in Oakley where there has been a spray miss such as next to telegraph poles, showing the effectiveness of fungicides,” he said. “Watch out for some mildew creeping in on late sown crops suffering from drought stress.”

Spring beans would soon begin flowering and due to low downy mildew levels, fungicide savings could be made, he said. “Winter beans are well into flowering and setting pods – a final fungicide will be required soon to keep chocolate spot under control and protect against rust.”

Excessive temperatures over the weekend, caused flag leaves to emerge at a rapid rate, said AICC agronomist Ruth East from Lincolnshire. “Hopefully, all flag leaf sprays will have been applied by now, even though the time interval between T1 and T2 has been short.

With soil temperatures rising, and rain forecast, orange wheat blossom midge could be the next problem, she said. “Where crops are approaching GS52 and are not resistant to orange blossom midge, pheromone traps have been placed in fields.”

Sugar beet was growing well, but weed control had been challenging, she said. “Because of the dry conditions, there has been no help from residuals – hopefully when we do get some moisture they will begin to kick in.”

Disease pressure was low in Wiltshire and fungicide programmes had been more robust than needed, said Dan Dines from Wessex Agronomy Services. “Septoria is confined to old leaves, mildew is conspicuous by its absence and yellow rust has just not happened,” he said. “Hindsight is a wonderful thing, and if fungicide programs are viewed as an insurance policy, the premiums paid this spring have been too high.”

T3 fungicides were next on his agenda. “The emphasis in recent years has shifted towards fusarium and mycotoxins,” he said. “I feel there is a need for further research, as the level and reliability of control of the ‘ear disease complex’ tends to be variable.”

Click below to read the full reports

Crop Watch North – David Martindale

Crop Watch East – Ruth East

Crop Watch South – Swaran Bachoo

Crop Watch West – Dan Dines