Post-em sprays top priority in damp autumn
Post-em sprays top priority in damp autumn
By Andrew Swallow
WITH over half the winter cereal crop drilled, applying post-emergence herbicides to early-sown crops should now be a priority, say advisers.
Better than expected weather last week saw the area sown in England and Wales leap to near 75%, says ADASs John Garstang.
Even in Scotland about half the planned winter cereal area is drilled, in central and southern regions at least, says SACs David Cranstoun.
However, in Aberdeenshire and the Moray coast some are still struggling with harvest and have straw to clear. "They wont have ground ready to drill so may have to major on spring crops next year," he notes.
In England grassweeds in early-drilled crops have thrived in the warm and wet conditions. Growers must now watch they do not get too big to control, warns Mr Garstang.
"Some will be reaching tillering already. If that is the case, get a herbicide on as soon as you can, but take care with the wind and follow the ipu stewardship guidelines."
BASFs Andrew Jones suggests a pendimethalin/flupyrsulfuron-methyl mix as an alternative to ipu and a better bet where resistance is an issue. "The pendimethalin is less mobile in the soil, therefore less prone to leaching. But maintain the doses – 3.3 litres/ha of Stomp and a full rate of Lexus in a blackgrass situation."
That advice is echoed by IACR-Rothamsteds Steven Moss, but only where resistant blackgrass is known or believed to be present. "Theres more scope for cutting doses or using a cheaper mix in a non-resistant situation, but you have to be really sure. Resistance is so widespread now in some areas it is almost endemic."
For crops going in now, pre-emergence treatments could be particularly useful in case growers cannot get back on with post-emergence products later. Which to use will depend on the target.
"For wild oats Avadex is still a better bet but for blackgrass and ryegrass Crystal is a useful alternative," says Dr Moss.
BASF suggests delaying application of Crystal (pendimethalin + flufenacet) to the "peri-emergence" or "green haze" stage of the crop on cobbly seed-beds. "If seed is exposed there could be some damage," says Mr Jones. *
MONITOR LEXUS
Where growers have a brome problem, think carefully before using Lexus in the autumn because legally it rules out Monitor (sulfosulfuron) in the spring, says ADASs John Garstang. "You have got to decide where your priorities lie – blackgrass or brome. Maybe the thing to do is use different products on different parts of the field."
POPULATION SNAG
Low blackgrass populations, say 5-10 plants/sq m, allow cheaper options such as trifluralin/ipu or trifluralin/Lexus mixes to be considered, but beware of under-estimating, says IACR-Rothamsteds Stephen Moss. "The problem is at this time of year 50 plants/sq m wont look like very much but the damage that can do is phenomenal," he warns.
PROGRESS &PRIORITIES
• Drilling well on in all but extreme north.
• Grassweed sprays now pressing.
• Early crops top priority.
• Pre/peri-emergence treatments still worthwhile.