Crop Crack

Docks & Chickweed Are Major Problem In Silage Swards


As thoughts turn to silage, 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. FOREFRONT T may only be applied to grazing ground.  However PASTUREPACK launched last season by Nufarm will cover a similar range of weeds and may be applied on silage ground. 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 appear as 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 establishes grass.



There are 2 types of chickweed, common chickweed which has a smooth leaf and is the most commonly found, 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 spring as this weed grows at lower temperatures than grass, 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 ENVY andLEYSTAR will be used widely on new sown leys this season where clover is not important. As well as controlling both strains of chickweed it will give very good control of dock and thistle.

DOXSTAR applied at 1lt/ha, will control both types of chickweed in established swards. Neither will check the growth of immature grass plants and are not clover safe. 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 when used correctly. As well as controlling a wide range of BLW’s TRIAD gives excellent control on chickweed. It will also control seedling docks (not those regrowing from roots), but has no effect on thistles or buttercup. Add SPRUCE to bring in control of these weeds.

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.



Time To Focus On Crop Nutrition

The extremely wet and windy weather over the last couple of weeks has delayed fertiliser and spray applications. Crops have begun looking for nitrogen and as daylight hours are longer it is essential to apply fertiliser onto crops as soon as ground conditions allow. The amounts of P&K at the target index 2 must be maintained and it is important to take into consideration the offtake in yield of grain when planning fertiliser applications. As most of our straw is removed an NPK fertiliser should be applied in accordance with the RB209 taking into consideration the use of organic manures. Cereals are becoming more responsive to sulphur as atmospheric deposition of sulphur declines. Where deficiency has been recognised or is expected 25-50kgSO3/ha as a sulphate should be applied in early spring before the start of stem extension.

Fastmix Magnesium Plus contains the following available nutrients- magnesium, sulphur, zinc and manganese. This product is rapidly absorbed by the plant quickly correcting deficiencies. Fastmix has been specially developed to meet the micronutrient demand of cereals and other leafy crops with a high manganese demand in an ideal combination with magnesium and sulphur.  It is a cost efficient nutrient application technique for Mg, S, Mn and Zn without additional costs, if combined with the regular crop protection program.  It also helps activate nitrogen into the plant to enhance seed development and transference of sugars throughout the plant, sulphur is one of 17 elements essential for crop growth. Although sulphur is considered a secondary nutrient it is often referred to as the fourth major nutrient ranking just below NPK. Sulphur deficiency can often be mistaken as nitrogen deficiency. The pale yellow symptoms of sulphur deficiency often appear on the younger or uppermost leaves whilst nitrogen deficiency initially appears on the older leaves.

Crops lacking sulphur appear stunted, spindly and thin stemmed and maturity in cereal grains is delayed. When deficient, Mg is transferred in the plant from older to new tissue. As a result, deficiency symptoms occur first in older leaves. Tissue between the veins becomes light green to whitish in colour. In cereals this leads to striping between veins that may be intermittent rather than continuous. With severe deficiencies, purple colouration may follow. I have observed quite a lot of mildew especially on winter barley crops across the province over the last couple of weeks. I am advising a T0 fungicide treatment as rhynchosporium levels have also become quite high. It is also important to observe the winter wheat varieties when considering a T0 bearing in mind the low resistance some varieties have to mildew.


Weed Control Starts in Wheat & Grass Reseeds

Autumn 2018 was again kind to us, allowing much of the winter barley and some winter wheat to receive a herbicide treatment during October and November. Mixtures of CRYSTAL and SEMPRA were widely used and by and large, performance has been excellent.

Control of Annual Meadow Grass (AMG) is the first priority in all crops if not already done with an autumn treatment. OTHELLO or HAMLET is an excellent contact solution for AMG in wheat in the spring, however there is no similar contact option for barley. None of the autumn products will control AMG beyond the mid tillering stage, yet they are the only AMG options for barley. Note that the actives in both HAMLET and OTHELLO that control AMG (iodosulfuron and mesosulfuron) will only control AMG that has already emerged; unlike the autumn actives these are not residual and have no pre-emergent activity. HAMLET provides a useful alternative to OTHELLO and is very effective on a wide spectrum of grass weeds. HAMLET has greater flexibility as the label allows a higher rate giving better activity in larger weeds. HAMLET works extremely well in cooler temperatures.

Both OTHELLO and HAMLET will also control a wide range of pre or early post emerged broad leaved weeds, but where these weeds have size then a contact product needs to be added to ensure larger overwintered BLW are controlled effectively. Where the AMG has been controlled in the autumn but for example over-wintered chickweed, cleavers or groundsel are problems weeds now, ZYPAR is a more effective option controlling these and most other emerged BLW.

Brome grass and wild oats

Brome grass infestations continue to be prevalent right across the province. Last season saw a decline in the numbers of infested fields, Effective control can only be achieved using a combination of cultural and chemical control methods. Cultural control methods (break crops, stale seedbeds).Chemical control then is a sequenced approach of an autumn treatment followed up with a spring treatment. CRYSTAL at 4lt/ha in the autumn was the first part, and should have been applied to wheat and barley. The follow-up then in the spring is BROADWAY STAR but note this product can only be used on wheat. There is no follow-up brome product available for barley and therefore in a severe infestation situation, only wheat allows effective control.

To avoid crop damage, do not spray any crop under stress. Note that performance of some wild oat/brome herbicides can be adversely affected by other herbicides used on the crop. To avoid these antagonisms, a minimum time interval must elapse between applications of the various herbicides.

Need a T0 Treatment?

Rhynchosporium and Septoria are the two most damaging cereal diseases in NI. Both have always been more effectively controlled protectantly, but in previous times where the curative properties of the azoles were able to rescue a bad situation later, particularly in wheat this is no longer the case. Growers must now change their approach, looking to keep ahead of both diseases by starting earlier than before and maximising the protectant activity of the chemistry available then right through to crop senescence.

In barley the lower leaves contribute more to grain fill than the upper leaves and therefore particularly in a year like this where crop was drilled early last autumn, plants are forward and disease is already present, so a relatively cheap T0 applied within the next few weeks will reduce the level of inoculum present keeping the newly emerging leaves clean and allow the T1 be better timed and protectant focused. Most of the azoles still have good curative activity on Rhyncho and the addition of morpholine will help control the high level of mildew present.

Treating Chickweed In Reseeds

There was a large amount of reseeding of poor performing grass fields last autumn. Now is a good time to check whether a herbicide spray is required to clean these fields up. Getting rid of annual weeds such as chickweed or seedling perennial weeds such as docks and thistles, is vital to ensure the investment in reseeding realises its full potential.”

Even though only an annual, chickweed is the most competitive and potentially damaging weed to new grass leys. This year’s mild winter has allowed chickweed to become very strong and competitive in the sward. If not controlled, chickweed levels will build up and will very effectively choke out the young grass; populations of 10plants/m2 can reduce the ryegrass population by as much as half. Therefore chickweed should be treated as soon as possible if ground conditions allow.

Whilst in the past many hormone herbicides had approvals for use on new sown leys, in recent years almost all of these approvals have been revoked, and the range of products today is limited to a handful. Product choice will be dictated first depending on whether clover is an important part of the reseed mixture or not. Where clover is important, broad spectrum product choice is limited specifically to TRIAD in mix with SPRUCE. Where clover is not important, the choice is essentially between ENVY and LEYSTAR depending on which weeds are to be controlled. Leystar from Corteva Agriscience has three effective active ingredients, fluroxypyr, clopyralid and florasulam, which combine to control a wide spectrum of annual weeds, such as fat hen, red shank and mayweeds, as well as seedling docks and thistles.

Leystar can be applied from 1 February to 31 August in new sown leys in 200 litres of water, so can be used on autumn-drilled and spring-sown grass reseeds. It has good grass safety, but will kill clover or any broad-leaved weeds that have not germinated when the herbicide is sprayed..

For best results apply to weeds that are small and actively growing, and when the grass has reached the three-leaf stage.

ENVY is an excellent herbicide choice for autumn reseeds as it works very well in cooler temperatures. ENVY can be applied between 1st February and 30th November. Trials done with ENVY have shown excellent results on chickweed much better than straight fluroxypyr.

Allow an interval of four weeks after application before cutting grass to optimise the effect of the herbicide. Do not roll the grass for ten days before or seven days after application. If the fields are to be grazed, animals can return just seven days after application. Farmers must be certified to use professional use herbicides on their fields.

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