After a particularly mild and wet winter, most pastures contain an abundance of poor-quality material in the base of the sward which will result in lower quality first cut silages unless steps are taken to address the problem. With above average temperatures through November, December and January, grass growth has been good but the mild and moist conditions have led to the build-up of dead leaves in the bottom of the sward. On heavier ground, soils have been waterlogged for considerable periods with the grass plants becoming chlorotic and yellow.
A wet autumn followed by a very wet spring means weeds are thriving and giving grassland farmers yet another problem to contend with.
Many pastures were left unsprayed in the autumn as the wet weather set in, allowing grassland weeds to become more established than ever. Weed-infested grasslands pose an additional economic burden for livestock farmers by reducing the quality and quantity of available forage.
Added to this, farmers have been contending with higher levels of poaching this season, another risk factor for vibrant weed growth. Although typically associated with cattle, even sheep are causing poaching issues on the unusually sodden land. Poaching creates thin areas of pasture and gaps, potentially leaving a more open sward as well as disturbing the soil structure and can allow problem weeds to encroach in these areas. We are currently seeing problems with chickweed, buttercup and docks.
If you are reseeding, don’t forget weed control in the newly sown ley. Once grasses have reached the three-leaf stage, check whether a herbicide spray is needed to remove any annual weeds, such as chickweed and redshank, or perennials such as docks and thistles. Left unchecked, they’ll take hold and smother the new grass.
Herbicides should be applied when weeds are small and actively growing. It is more economical and effective to treat weeds at this stage than wait for them to establish and treat when they are bigger.
Product choice very much depends on the weeds present and the intended cutting time. For many farmers weed control will now be planned after the first cut. No spray will give complete dock control with a single application. Long term control can only be achieved using a sequence of applications using translocated herbicide because of the potential of regrowth, both from roots, and from seed in the ground over the years. A follow-up application will deal with seed germinating in the bare spaces and shaded docks which were not controlled in the first treatment. For a sequence of applications, the best timings would be spring (mid-April to June) and then a follow-up spray on any regrowth in the autumn (late August-September) or following spring.
Docks
Treating dock-ridden leys with DOXSTAR PRO four weeks before cutting will significantly increase the amount of grass that ends up in the clamp and improve silage quality. Docks have much less feed value than grass and pull-down dry matter. FOREFRONT T is the most effective herbicide available to grassland farmers for the control of docks, ragwort, chickweed, thistles, dandelions, nettles and buttercups. It is the longest lasting weed control product in grassland to date with a single well-timed spray giving up to 18 months control so whilst it may appear expensive it really is good value for money. Once the established docks have been controlled it is best to keep the problem under control with follow-up treatments every year. This controls new growth of seedling docks that will reappear because all that is required for dormant seeds to germinate is a gap in the sward caused by poaching or tractor marks.
In fertile soils, the dock root system consists of a large tap root with a highly branched mass of smaller fibrous roots. This means what appears to be a small dock plant above ground may in fact be growing from a large rooting system below ground. In order to achieve effective herbicide application docks should be at the rosette stage, with foliage8-10 inches high or across. If grass has been cut or grazed a period of three weeks must occur to allow sufficient regrowth and a suitable target for spraying. If applying FOREFRONT T, DOXSTAR PRO or PAS.TOR, livestock should be kept out of treated areas for 7 days before grazing and until the foliage of any poisonous weeds has died and become unpalatable, where clover is important SQUIRE may be applied in established grass.
Chickweed
There are 2 types of chickweed, common chickweed which is the most commonly found type, with a smooth leaf and mouse-eared chickweed which has a larger leaf than common, with a very hairy surface on the leaf & stem. Chickweed levels have built up very quickly this season .and should be treated as soon as possible to avoid choking out the young grass. Similarly, established swards that have been poached by autumn grazing tend to be very open in the early spring and this allows chickweed a chance to become a problem. Chickweed can mature and produce seed in 5-6 weeks hence there can be several generations in a year. Mouse-eared chickweed is very common on many local farms and it is important to note the distinct differences and treatments. Both LEYSTAR and ENVY control both strains of chickweed and will be used widely on new sown leys this season where clover is not important.
Where clover is part of the mixture then a clover safe product must be used. TRIAD is an SU type herbicide that is safe to clover.
It is extremely difficult to achieve satisfactory control once weeds get beyond the seedling (young plant) stage. Clover content of the sward needs to be higher than is often appreciated. As a rule of thumb there should be 10 plants per square metre at the start of the season. Where plant populations are below this level it is more important to focus on other aspects and be prepared to treat the field as a grass only crop. High levels of nitrogen will significantly reduce clover growth, but by reducing nitrogen inputs overall forage yield will be reduced.
