Crop Watch: Pests picnicking on profit
Pest pressure remains high in crops this week, say our Crop Watch agronomists, particularly now pigeons have joined in numbers to further threaten vulnerable crops.
“Since my last report, there has been very little opportunity to carry out any fieldwork, except more slug control,” says Strutt and Parker agronomist Ryan Hudson. “The relentless battle continues and now pigeons have joined the picnic.”
Mr Hudson has had the harsh reality of failed crops, he explains, and where these failures have been realised the land is likely to be left fallow. “Where this is the case a cover crop will be considered to take up moisture, maintain structure and add biomass to the land,” he says.
Meanwhile, in the South, ProCam’s Nick Brown has also been having an endless nightmare with the slugs and has gone some way to explaining the differences in the level of damage in certain situations.
“Crops established after cultivations based on more aggressive, multiple passes carried out early on in relatively dry conditions have significantly less slug damage, even if the final drilling pass was delayed,” says Mr Brown.
“This is not because the seed-bed was any finer, but because many more slug eggs and slugs were killed in the process. However, direct drilled wheat crops look very sorry, leading me to the conclusion that diesel was probably the most effective slug killer this year,” he adds.
Another, less visible, pest has appeared in numbers amongst cereal volunteers in the West, where Countrywide Farmers’ agronomist Neil Donkin is thinking about his barley yellow dwarf virus (BYDV) control strategy.
“Those volunteers are harbouring large numbers of aphids, so the BYDV risk is now high. Deter (clothianidin) seed dressings will last between six and eight weeks, but after that a follow-up treatment is advisable,” says Mr Donkin.
“Apply an aphicide at two- to three-leaf stage of the crop, if field conditions allow.”
Also at the two- to three-leaf stage in wheat crops in Mr Donkin’s area is blackgrass, with many growers unable or unwilling to apply post-emergence herbicides. “The weed is now growing away unchecked,” he warns.
“At this stage it is probably best to apply Atlantis (iodosulfuron + mesosulfuron) or Unite (flupyrsulfuron + pyroxsulam) in combination with a residual partner. Little else is likely to have much of an effect on established blackgrass, but the downside is you have used your heaviest weapons early in the season,” say Mr Donkin.
In Perthshire, AICC agronomist Hamish Coutts says most of his wheat area will miss out on a herbicide this autumn, unless the weather gods change their mood. “If a suitable opportunity presents itself, then grassweeds are easier to control when they are small,” he says.
“Otherwise, the best approach will be to wait until spring to see if the crop survives and to assess the weed spectrum. Growers should check the cut-off dates of most residual and early post-emergence products, if applying before the spring.”
Mr Coutts is also struggling with other treatments. “Getting a spray onto oilseed rape for light leaf spot or an aphicide onto winter barley for BYDV may prove a bit tricky without a low ground pressure sprayer.”
Lack of care about metaldehyde stewardship guidelines is causing a concern for Mr Coutts and he points out that despite the best efforts of agronomists to work within guidelines, it would appear that some growers, while trying to prevent total crop failure, have not been too precise with their applications.
“The net result is high levels of metaldehyde being found in watercourses. We cannot afford to lose our concentration in this stewardship campaign or we shall lose yet another control mechanism,” he says.
Read the full Crop Watch reports here.
