Crop Crack

Spring Crops Make Good Start

Spring Cereals

The much more pleasant milder night-time temperatures have seen a welcome burst of new growth in all crops. All spring crops have now brairded and without the more usual effects of waterlogging seen in other years, are looking very well. Although weeds are also emerging fast as a result of last weeks rain, be sure all are well through before spraying. Watch too the size of the annual meadow grass if this weed is also to be controlled – efficacy falls off rapidly once it begins to tiller.

A well timed application of SELON will encourage tiller numbers and tiller survival. This treatment must be well timed to maximise its effect, optimum timing for barley is from the 2 expanded leaf stage to beginning of tillering, GS12–21; in wheat the optimum timing is slightly later, 5 leaf to mid tillering, GS15-24. Many crops will have now passed through these growth stages. It is important to note that this season aphid numbers are the highest I have seen for a very long time and it would be advisable to apply an aphicide to control the spread of BYDV.

To minimise the effects of competition on the crop and optimise the level of weed control, herbicide application should be carried out once all weeds have emerged but are still small, and before they begin to compete with the crop for nutrients and light. Carrying out the weed control when they are at the 2-4 leaf stage is much more effective especially on difficult weeds such as fumitory and knotgrass, rather than delaying to coincide with the 1st fungicide application.

Broad leaved weeds resistant to particular groups of herbicides in NI is not a new problem – chickweed resistant to herbicides such as ALLY has been widespread throughout the province for some years. Sulfonyl urea (SU) herbicides such as metsulfuron have a single mode of activity, blocking the production in many BLW of a key enzyme, acetolactate synthase. Products that use this mode of activity are known as ALS inhibiting herbicides and include the SU chemistry. As well as chickweed, mayweed and poppy have also developed widespread ALS resistance. This particular resistance problem has been managed by including herbicides into the tank-mix with different modes of activity to maintain good weed control.

 

In NI spring cereals ZYPAR will give excellent control of a wide range of weeds that includes chickweed, fumitory, fat-hen, groundsel, brassica weeds, and cleavers. Its one relative weakness is redshank. Whilst it will control it to 6-leaf, it should be tank-mixed with another herbicide to ensure redshank right up to flowering is satisfactorily controlled. ALLY MAX and FOUNDATION are excellent tank-mix partners for this purpose.

 

Temporary nutrient issues

Manganese (Mn) deficiency is widespread in much of our local soil types, and particularly damaging to leaf vigour and yield if not treated. Continuous cereal cropping, ground recently limed and dry soils all increase the likelihood of deficiency. Symptoms begin with small pale green speckles appearing throughout the leaf and these will progress to turn brown unless treated. Barley is particularly susceptible to Mn deficiency. MAXMAN is a highly concentrated Mn(40%) in a completely soluble chelated nitrate formulation and also supplies 10.8% Nitrogen and 11.4% Sulphur

A young plant that is growing extremely rapidly is producing a huge amount of new plant tissue each day. This rapid growth is limited only by the availability of nutrients to synthesise biomass, dependant on soil fertility and the plant’s own root development to take up the nutrients. It is at this time therefore when nutrient deficiencies are most likely to appear and in doing so, suppress growth rates.

The application of a broad-spectrum trace-element mix along with key macronutrients during this time is a very useful and beneficial way to supplement the plant’s nutrient requirements during periods when availability does not meet demand, most likely to coincide with phases of rapid growth ie. during tillering and as stem extension begins. Application of a balanced and readily available source of macro & micronutrients that is topping up what is being made available from the soil at this key time will minimise the adverse effects of restricting nutrient availability. CEREAL HIGH N-supplies 250gm N, 125gm S, 38gm Mg, 93gm Mn, 45gm Cu and 15gm Zn per ha

FASTMIX MAGNESIUM PLUS is an alternative product specifically formulated to meet the increased micronutrient demand of cereals and other combinable crops with good yield potential. It is a quick acting foliar fertiliser containing high levels of magnesium and sulphur as well as manganese, zinc and boron, all in a water soluble form and readily available to the plant. It is very compatible in tank-mix with most pesticides and can be applied along with the T1 and T2 fungicide applications. Being a dry formulation, it should be fully dissolved in the tank first and other products added afterwards.

 

Winter Cereals

Winter cereals have greened up well and are now racing through the growth stages. Awns are now out on all winter barley crops with both T2 application and growth regulator applications complete. Winter wheat crops which have not yet received T2 should be treated as soon as possible along with the growth regulator if required.

 

Crops Going Through Growth Stages Rapidly

Winter Cereals

Winter cereal crops are moving rapidly through their growth stages. As a result of the predominantly dry April and better timed spray treatments than many other years, the wet weather diseases, Septoria and Rhyncho remain lower down the plants, well controlled by the T1 application. Dry weather diseases have been more problematic this year, with Net Blotch, mildew and Ramularia appearing in barley and Yellow Rust and Mildew in wheat.

As awns appear in barley and the flag leaf emerges in wheat, the T2 fungicide timing is fast approaching.

Properly protecting the top three leaves and ear at T2 is critical to yield and profit – foliar disease not controlled effectively at this time will hasten the senescence of these leaves during grain filling, and therefore impact adversely on yield and grain quality. This treatment will extend canopy duration therefore increasing the amount of starch produced for grain filling, and increase grain storage capacity leading to higher thousand grain weight (TGW).

Winter Barley

Correct timing of fungicide applications is critical to optimizing activity and product performance. The T2 treatment should be applied from flag leaf sheath extending, through booting to first awns visible, GS41-49. As well as protecting against Rhyncho, this treatment also needs to protect the plant against Ramularia, Brown Rust and Net Blotch through to the end of the season. Awns contribute equally to yield and it is important to keep them free of disease also.

For crops with good yield potential, the inclusion of SHDI along with triazole and multi-site is very much the norm now, ensuring persistency of the treatment right through to ripening. Best options include AYLORA or CONCORDE mixed with MOBIUS/MANTRA/RUBRIC and the multisite chlorothalonil. Good practice would be to use a different SHDI/triazole combination now to that already used at T1. Where a crop with lower yield potential discourages their use, non SDHI chemistry using triazole/strobilurin/morpholine mixes are also robust options eg OPUS-TEAM, MANTRA or MOBIUS. As a result of its resistance to triazoles and the SDHIs increasing, chlorothalonil should now be considered an essential component of all T2 treatments helping the control of Ramularia.

Winter Wheat

In wheat the T2 should be applied during the emergence of the flag leaf, GS37-39. Of all treatments, this flag leaf timing is the most responsive to yield and therefore products used should reflect this. Against a background of Septoria being present in all crops and significantly reduced kickback activity from core chemistry, the T2 timing is critical to ensure effective protectant performance.

Managing resistance and maintaining reliable disease control now means using a range of different actives over the course of the growing season

It is good practise to use different actives from within the same chemical group at the different spray timings. Where possible, use a different SDHI at T2 to that used at T1, and likewise use different triazoles over the course of the season to give the widest possible activity across the different strains of fungi of all diseases.

Because it provides multiple modes of activity acting preventatively on Septoria and has no known resistant strains to the disease, chlorothalonil should also be included in all well timed T2 programmes to provide some control of those strains now showing resistance to triazoles and even SDHIs. In crops susceptible to lodging a plant growth regulator should be applied at this time.

 

Docks & Chickweed Are Major Problem In Silage Swards

Docks

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.

 

Chickweed

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.

 

 
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