All weed control should now be almost complete on spring cereal crops. There was certainly plenty of opportunity to catch up on spray programmes over the last couple of weeks. Crops are moving through the growth stages very quickly this week with the damper conditions. Some spring barley in parts of North Down are already at flag leaf and East Down have crops with awns appearing. Wild oats may be controlled now as long as a period of three weeks has occurred from the weed spray application. Axial and Adigor may be used on both spring barley and spring wheat up to flag leaf. It is certainly a season where growth regulator will be required in abundance. As most crops are now past 2nd node growth regulation products are limited to Cerone for barley up to first awns visible and Adjust and Cerone on to spring wheat up until flag leaf sheath opening. Fungicide application is priority now as rynchosporium is spread by rain splash. This disease has been present in low levels up until now with netblotch being the most dominant disease in spring barley. Whatever the fungicide choice for spring wheat it is critical to include something to cover mildew as most varieties have mildew present on them.
Protecting the top three leaves at T2 is critical to yield and profit – up to 80% of the yield is generated from these leaves. Foliar disease not controlled effectively at this time will hasten the senescence of these leaves during grain filling, and therefore affecting yield and grain quality. Yet there is little point in applying any input if it does not give a financial return. To get the best return on fungicides, applying them at the correct timing is critical. Trial work in UK & ROI has consistently shown even in a low disease pressure year, a well-timed application will give returns of 2-4 times their cost and in high pressure situations 5-6 times their cost. In winter barley this should be applied from the end of booting through to awns fully emerged, GS45-59, and be robust enough to protect the upper leaves and ear through to the end of the season. Awns also contribute to yield and it is important to keep them free of disease also.
For winter wheat the T2 should ideally be applied between mid flag leaf to mid-booting, GS38-45 along with the growth regulator. The T3 treatment is then applied post ear emergence to mid flowering, GS59-65, targeting ear diseases and prolonging control of foliar disease on the top two leaves, especially important in wetter seasons and on susceptible varieties.Sumi-alpha should be applied along with the fungicide.
Much of the potato crop this season has gone into cold soils and therefore drills are only warming up now. Both weeds and potatoes have been slow to emerge to date. Most weed control programmes are based on residual products ie products that are taken up through the soil, and are therefore very dependent on sufficient soil moisture to work effectively. Soil conditions are ideal therefore at the moment, moist enough on the tops of the drills to allow the herbicide be taken into the soil and taken up by the germinating weeds.
A huge amount of SAC work suggests that growers should spray before crop emergence to moist clod-free ridges. Holding off until crop emergence will set the potatoes back significantly reducing final canopy cover, and compromise weed control especially if weather delays the application further. The weeds are best treated pre or very early post emergent, especially important on the difficult weeds; fumitory, knotgrass, bindweed, annual meadow grass.
The key message is to apply the herbicide combination before crop emergence, therefore avoiding any check to the crop once emerged and maximising range of weeds controlled.
It is Tuesday today as I write this article and the steam is rising up from the road as I look outside. This certainly has been the first day since potato planting I could say there is a risk of blight. During the early canopy development phase, emergence to rosette products that have zoospore activity are the most effective 1st spray. RANMAN, SHIRLAN or TIZCA will control any zoospores that may be in the soil (either from ground-keepers or infected seed) and provide good protection of the new plant.
With farms being short of grazing because of the cold conditions 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 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.