Crop Watch: Agronomists bemoan changeable weather

The changeable weather has forced this week’s Crop Watch agronomists to reassess their weed control plans and T0 timings.
“We’ve just had 10mm of rain,” says Brian Ross of Frontier. “Not a staggering amount, but with more promised during the week, there is a sigh of relief. Admittedly a lot more is needed to catch up, but it’s ideal for the nitrogen that has been applied and helpful for the spring crops that have been drilled so far.”
In contrast, Paul Sweeney of AICC says no thanks to any more rain. “While the rest of the country may be desperate for rain, we’re just grateful for a bit of dry.” Ground conditions have improved enough for nitrogen to be applied to most rape crops and the few late-sown wheats that we’ve got.”
In the west, AICC agronomist Stephen Harrison says it has been a busy week for spraying with a lot of contact graminicides applied to winter wheat in ideal conditions. “Cleavers look green and fresh, therefore, a low dose of amidosulfuron has been included where appropriate. The next spraying target will be mayweeds, cleavers and thistles in winter oilseed rape with Galera (clopyralid and picloram).
He adds that autumn Atlantis (iodosulfuron + mesosulfuron) has generally worked well, however places where controls seems poor need recording so seed samples can be collected and sent off for resistance testing pre-harvest. Spring applications have been going on in the last couple of weeks, where there has been fresh growth visible.
However, Mr Ross adds that blackgrass in many fields in his area are still blue/red and flat to the ground, so are not growing as actively as they could. “Waiting until good growing conditions with no tank mixes should ensure the best out of the product.”
In oilseed rape crops, buds are now appearing above the crop and Mr Ross believes it won’t be long before pollen beetles will be of concern. “Increasing pyrethroid resistance, particularly in the eastern region, means that choice and correct timing of treatments will be of paramount importance.”
Mr Sweeny adds: “We are just sizing up which ones [OSR crops] really need growth regulator (fungicide) treatment and which can be done more naturally by manipulating nitrogen applications. However, some will have to be done this way especially where the plant population is too high.”
Looking to T0, Mr Sweeny says some applications will start this week, along with aphid control in many crops. “We have had insufficient frost to see off aphids and they can be found easily together with emerging gout fly. Aphids and the threat of Barley Yellow Dwarf Virus is still as serious as ever and they need taking out.”
Mr Harrison adds that his clients haven’t been drawn into pre-T0 treatments in wheat. “We will focus our efforts on leaf four upwards. Some very forward winter barley crops will receive a T0 based largely on cyprodinil mixed with spiroxamine where rust is an issue.”
Tim Bullock of Agrovista says that mildew levels are staying fairly low at the moment and rust levels are variable. “Oakley, Solstice and Cordiale are carrying the most, but are not the only ones with some.
“Where sprayers are going through, either for grassweeds or manganese deficiency, if needed I’m adding in a low dose centaur (cyproconazole) to take out the rust in the hope that will prevent us from needing to bring T0 applications forward.”