Septoria and yellow rust levels are being closely monitored in winter wheat crops with T0 fungicide choices coming under the spotlight, say our Crop Watch agronomists this week.
AICC agronomist David Martindale notes that septoria levels are building up in wheats, although he hasn’t seen any yellow rust yet.
“It will soon be time to consider T0 fungicides on the earliest wheats before long on Septoria tritici or yellow rust susceptible varieties, such as Oakley and Solstice,” says Mr Martindale, of Arable Alliance, Yorkshire.
“This fungicide can often be coincided with any plant growth regulator that is required and will consist of a triazole with chlorothalonil.”
In Lincolnshire, septoria levels are high and mildew has been found on forward wheats, so a specific mildewicide may be added to the T0 tank-mix, according to Farmacy agronomist Philip Vickers.
“If the disease is checked by the weather, a mildew-suppressing triazole may suffice,” he says.
Wheat bulb fly is still causing concern and crops that received chlorpyrifos three weeks ago are showing some deadheart symptoms and some need dimethoate, he notes.
In Wiltshire, Dan Dines of Wessex Agronomy Services, says careful management of fertiliser applications will be necessary to manage lodging risk in wheat crops.
“The first nitrogen application is being delayed on thick/forward crops until mid-March,” he says. “But given the two previous dry springs, we are reluctant to delay nitrogen applications too long.”
Mr Dines says the prolonged cold weather has delayed applications of Atlantis (iodosulfuron + mesosulfuron) on winter wheat for post-emergence control of blackgrass and other problem weeds.
“We need to balance the conditions at application while not letting blackgrass grow to big,” he suggests.
In Hampshire, Agrovista agronomist Swaran Bachoo says autumn residual herbicides have performed well, but cleavers and blackgrass have come through these treatments.
“Once temperatures reach 6-8C and active growth has started, it’s time to consider applications of Atlantis in wheat and Axial (pinoxaden) in barley,” he notes.
He reminds growers that it is imperative to apply grassweed herbicides as early as possible to achieve good control.
“If large cleavers are present then spray with Eagle (amidosulfuron) or Chekker (iodosulfuron + amidosulfuron),” he says.
“In many cases, only seedlings are present, so we will wait until most cleavers emerge before spraying them with Starane Vantage (florasulam + fluroxypyr).”
Oilseed rape crops are at 6-8 leaf stage and they should now grow rapidly as the day length is extending and the first split of nitrogen fertiliser has been applied, he notes.
“There is some light leaf spot starting to appear in some crops,” says Mr Bachoo.
“Where broad-leaved weeds are present, treatments should be carried out soon before flower buds become visible to avoid crop damage.”
Meanwhile, John Sarup, senior potato consultant for SAC, says clients in Cheshire started potato plantings a week ago into good conditions, particularly behind grass where the organic matter from the root mass keeps oil open and friable.
“Soil temperatures are generally below 8C. However, covering with fleece within a day of planting tends to make use of any warmth from the weak sun,” he notes.