Bedfordshire agronomist Andy Scott. Cereal growers will have to rely on contact herbicides to control broad-leaved weeds in the spring following one of the worst autumn campaigns in living memory, exacerbated by twice the annual rainfall (36 inches) up to the end of November.
Poor weed control could have a significant impact on yield in open and uncompetitive crops says Bedfordshire-based agronomist Andy Scott. With wheat prices for November 2013 currently at about 180/t a robust herbicide programme that includes full rate contact and residual chemistry is a small price to pay for a good economic response.
Andy says he cannot recall a year as bad as 2012. Almost continual rain throughout the summer and autumn has meant that only about 50% of the cereal land in his area has been drilled. The result is mostly backward and open crops that will face competition from overwintered resistant blackgrass and broadleaved weeds.
Most crops that were drilled early and received a pre-emergence herbicide failed to have a post-emergence follow up and later drilled crops failed to benefit from either.
Growers intended to leave crops for as long as possible to encourage a green bridge but heavy rain following the brief dry period during September prevented any drilling. Crops that have been drilled are showing poor emergence and vigour. Slugs are a real problem too and the cold/wet soils have slowed emergence, says Andy.
The land isnt fit and it wont be until January at the earliest. Most winter cereal varieties can still be drilled up until the end of January, with a few until the end of February but after then, growers will have to opt for spring crops. It is likely we will see an increased acreage of spring barley, some spring beans and spring oilseed rape.
Herbicide options for growers are now limited, he says. A small window of opportunity resulted in some land being sprayed off with glyphosate and for a while these fields looked yellow. But on closer inspection newly emerged black-grass and broad-leaved weeds have since emerged. He says that contact herbicides offer the best opportunity for growers to keep ahead of the weeds.
Crops that have not been treated with a pre-emergence herbicide will almost certainly have emerged non-sensitive black-grass to deal with. Andy says that contact herbicides offer the only real option for maintaining satisfactory levels of control. Presite (metsulfuron-methyl + thifensulfuron-methyl), provides stronger activity on certain broad-leaved weeds, for example common poppy, than straight metsulfuron-methyl. Tank mixing with Starane for improved control of cleavers, CMPP for fumitory and HBN for field pansy.
Contact materials plus a residual partner such as Atlantis plus clodinafop plus DFF applied when conditions allow or at the earliest opportunity is advised, followed by tank mixing full rate Presite for remaining broadleaved weeds and Starane for cleavers, he says.