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Crop Crack 21.05.11
By Wendy Fearon
There can certainly be no complaints of crops under drought stress after recent days. The rain has certainly encouraged weeds in all crops and these should be treated as soon as possible. Leatherjackets continue to be a serious problem with damage evident in many fields and lawns.
Cereals
Many crops were suffering from nutrient deficiencies directly linked to the extremely dry conditions. Nutrient uptake from the soil requires soil moisture, as all nutrients move from the soil particles into the root as salts dissolved in the water component of the soil, the soil solution. Many crops with the potential for wild oats should be treated as a separate application to the weed control, AXIAL and ADIGOR may be used up to full flag leaf in both spring barley and wheat for wild oat control. A period of 21 days must elapse between broad leaved application and wild oat control.
Up until now most spring cereal crops were very clean but the recent unsettled weather will have encouraged the spread of foliar disease. Trial work continues to underline the responsiveness and improvement in margins of spring barley to a correctly timed 2-spray fungicide program. An early T1 application at early stem extension followed by a T2 application during ear emergence will consistently outperform a single application. OPUS TEAM, ALTO ELITE and COLSTAR may be applied as T1 in a two spray program. Where one fungicide only will be applied MOBIUS or MANTRA are other options. Winter wheat and winter barley should all have received the T2 fungicide application and winter oats should be treated shortly. Later drilled winter wheat crops are now at GS39 and consideration should be given to growth regulation along with the T2 treatment. Crops will only be utilizing earlier applied nitrogen now and the present good growing conditions will move crops on. Either CERONE or MODDUS may be applied along with ADJUST up to GS39.
Potatoes
Both potatoes and weeds have emerged with great vigour over the last fortnight. Best weed control results will be achieved just prior to the crop coming through. The residual products will work very well with the soil moisture, preventing germination of target weeds. Most herbicides have only one mode of activity; i.e. a contact will have no effect on weeds not yet emerged, while most residuals will not control weeds already emerged. RETRO, ROUNDUP ENERGY and TITUS are all contact herbicides whereas SENCOREX, DEFY and LINURON are residual.
Shogun has a full recommendation for scutch control on ware potatoes. It will also give excellent control of perennial ryegrass, wild oats and volunteer cereals.
Grass
With farms being short of grazing because of the drought it is important to minimize the effects of encroaching perennial weeds. When targeting nuisance perennial weeds such as docks, nettles and thistles it is important to apply herbicides when the plants are actively growing and at the correct growth stage.
Most herbicide applications to silage ground occur prior to or just after first-cut. Depending on cutting date, the quality and quantity of silage taken will vary, placing greater importance on achieving the best second-cut possible.
Perennial weeds such as docks can significantly affect both the quantity and quality of grass harvested, so well-timed herbicide applications after first cut can reap rewards for the rest of the season and even into the next spring. This is likely to be particularly so this year with recent rainfall in Northern Ireland helping to stimulate weed growth. To optimize results, wait for 2-3 weeks after cutting for docks to regrow to the rosette stage, and then apply DOXSTAR to actively growing plants. Doxstar has been developed to deliver the highest levels of dock control. The formulation and the presence of two actives; fluroxypyr and triclopyr, delivers a significantly higher level of control than straight fluroxypyr.
Good levels of weed control can also be achieved in grazing leys at this time of year.
Where mixed weed populations are present, including docks, nettles and thistles, PASTOR is the most appropriate product to use. With the dry spring limiting grass growth, stock will have to graze closer to thistles leaving sheep vulnerable to orf. Getting rid of thistles in sheep pasture with THISTLEX significantly reduces the spread of orf while increasing grassland productivity.
FOREFRONT may be applied onto grazing ground giving excellent weed control with no effect on the grass. FOREFRONT contains Fluroxypyr and aminopyralid. As well as controlling docks it will control chickweed, buttercup, dandelion, nettle and thistle.
Treat weeds at the rosette stage, when they are actively growing. If stem extension is already occurring, use a mechanical topper first, and then treat regrowth when it reaches the correct stage.
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