Crop Watch: Soils still too cold for sulfonylurea

Spring drilling is making good progress, but soils are still too cold for sulfonylureas to be applied, say our Crop Watch agronomists.

In the south, H L Hutchinson agronomist James Boswell from Kent said spring bean drilling was in full swing and seed-beds looked good. He was advising growers to apply a pre-emergence herbicide as post-emergence options were limited. “Linuron, clomazone, imazamox and pendimethalin is a popular tank mix.”

Disease levels in barley were low with rhynchosporium and net blotch difficult to find, he said. Wheat crops had managed to survive the harsh winter, but growth had been slow. “Rust and mildew levels are also low and septoria seems to be the biggest threat.”

Although soils were drier, they were still too cold to apply sulfonylurea herbicides, he said. “Performance will be impeded until soils warm up.”

Dry fields allowed early nitrogen and P&K fertilisers to be applied in the west, said Countrywide Farmers agronomist Neil Donkin from Gloucestershire. But there was little crop growth so nutrients had not been taken up. “However, as it’s so dry there is no danger of leaching and the fertiliser will sit there until needed.”

Slow growth meant T0 fungicide applications were likely to be pushed back to the end of March/early April, he said. “It’s still too cold for Atlantis (mesosulfuron + idosulfuron) applications and this may eventually coincide with T0 spraying – if this happens, take note of Bayer’s tank mix recommendations.”

Conditions were suitable for applying Othello (mesosulfuron + iodosulfuron + diflufenican), but where weed size permitted it was sensible to wait for spring weed germination and control all weeds with one spray, he said.

Spring barley drilling was well under way in East Lothian, said AICC agronomist Andrew Riddell. Seed-beds were cooler than normal for the time of year, but soil conditions were good. “Aim to get some N, P & K into the seed-bed before drilling to maximise the efficiency nutrient uptake.”

Oilseed rape showed significant variation between fields with frosts hammering some crops. “Those with small canopies have shrunk and are now difficult to spot from the field gate.”

Winter cereals looked “rather ragged”, but soils were in good condition giving a sound platform for spring growth, he said. “Thoughts of T0 sprays are some time away, but we need to keep a close eye on crops as growth eventually begins – don’t forget about brome grasses and be prepared to take action when conditions allow.”

In Cambridgeshire, UAP agronomist Will Foss was testing soil mineral nitrogen levels in oilseed rape. “We’ve been using variable rate spreading to help even up canopies with this initial nitrogen application.” Low soil mineral nitrogen levels meant all crops received a top dressing in early March, he said.

Some cereal crops were suffering from frost lift, particularly those on chalk and lighter soils where seed was shallow drilled, he said. “The worst areas will be targeted with the rolls.”

A split plant growth regulator programme was planned, starting in mix with a T0 fungicide to improve root mass and anchorage, he added. “It’s unlikely to be applied until the first week of April unless conditions warm up considerably and drive crop development forward.”

Click below for the full report from each region:

Crop Watch South – James Boswell

Crop Watch North – Andrew Riddell

Crop Watch East – Will Foss

Crop Watch West – Neil Donkin