Crop Crack

Dry Weather Challenging For Young Crops

Most crops continue to benefit from the recent hot weather with many racing through the early stem elongation stages in a matter of days. However the late planting in May and dry weeks since make a challenging combination. With temperatures well above average and daylight hours considerably longer than for a crop drilled in early April, such conditions increase the likelihood of crop stress through too much or too little moisture, or not enough nutrient availability to support the potential rate of growth. As a result many fields are beginning to show variation of colour and growth, and such variation is very difficult to address in a satisfactory way. Manganese (Mn) deficiency is widespread in much of our local soil types, and particularly damaging 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.

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.

Spring Barley

Dry conditions have held back disease and at present all crops are clean, but in our typically moist climate the likelihood of Rhyncho and Net blotch infections breaking out are inevitable unless controlled in good time.

Even where crops are considered to be clean, controlling Rhyncho early is much more effective than leaving it until it is seen. Once this disease comes into the crop, any eradicant treatment has limited efficacy, will stress the crop and increase the risk of Ramularia infection. The T1 application should be applied at the end of tillering to the start of stem extension, GS24-31. The T2 is then applied 3-4weeks later during late flag leaf emergence to booting, GS38-49.

Product options continue to be based around core triazoles such as prothio, epoxi and cyproconazole. Prothioconazole remains the strongest performing triazole but epoxiconazole mixes are equally effective options, ensuring the various strains of disease are exposed to as many different actives throughout the programme as possible. Strobilurins continue to improve the performance of the triazole partner, improving Rhyncho, Net Blotch and Rust activity. MOBIUS is a mix of prothioconazole and strobilurin, and is one of the strongest barley products available. SDHIs will also give very good disease control at T1 but if they are only going to be used once then the T2 timing is the better fit for them as it is the most responsive timing in spring barley. Chlorothalonil is also an important component, enhancing the control of Ramularia when applied onto the flag leaf and ear.

 

All trial work continues to underline the responsiveness and therefore improvement in yield and margins of spring barley to a correctly timed 2-spray fungicide programme, consistently outperforming a single application programme. The ‘single hit’ approach attempts to provide protection for the 8-10 weeks required, an unlikely task in almost any scenario.

Where however a low input approach is been adopted, the one application will give best response when applied during mid stem extension GS32-33, maximising Rhyncho control on the upper leaves. This is normally some weeks after the optimum timing for the herbicide application. Mid stem extension is too soon however to get reliable Ramularia control and unlikely to prevent a late infection of Rhyncho.

Spring Wheat

The young spring wheat plant isn’t subjected to the same disease burden as the overwintered winter wheat plant, therefore a two-spray programme usually suffices, with the T1 applied at 1st-2nd node, GS31-32, and the T2 applied at some point during booting, GS41-49. Whilst a large proportion of these crops are harvested as whole-crop earlier than the conventional combined crop, the feed quality of the harvested crop is very dependant on maximising grain-fill, therefore product choices and rates are similar to those of the winter crop, with significant yield responses to a proper programme.

Spring Oats

Powdery Mildew and Crown Rust are the most damaging diseases in this crop. CAPALO & COMET in mixture is the strongest performer in terms of controlling both these diseases and therefore yield improvement. Metrafenone (an active in CAPALO) is extremely effective in terms of Powdery Mildew control. The addition of COMET (a strobilurin) gives unrivalled Crown Rust control.

CAPALO and COMET should be applied at 1st – 2nd node, (GS31-32) eradicating any Mildew and Rust already present, and providing persistency right through to harvest.

 

Lodging Control

Application of SELON at early tillering will have increased tiller and ear numbers and therefore yield potential, but will not have given any reliable strengthening of the straw. Stems that extend rapidly during the stem elongation phase (as has happened this season because of late planting and high temperatures ) are more likely to be weaker and so there is a greater risk of lodging especially where the crop is being pushed on with nitrogen. SONIS can be used but its cut-off in spring barley is 2nd node, GS32. CANOPY is a very useful alternative, safe to the crop and able to be used right up to and including full flag leaf, GS39. If this timing has past, CERONE can be applied up to before awns visible, GS45.

Because the application of SELON at mid to end of tillering (GS23-30) does give reliable later season lodging control in wheat, it is less likely than spring barley that spring wheat will need a growth regulator towards flag leaf unless the crop is particularly dense. If the crop still looks very rank and at risk of lodging as the stem elongates, apply CERONE only, as the flag leaf is emerging. The correct timing for treating spring oats is at 2nd node, GS32.

 

Good Weather Drives On Crops

The spell of glorious weather experienced over the last couple of weeks has made a huge difference with all of spring cereal crop now emerged and the early ones at mid tillering and beyond. 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.

Winter cereals for the most part are racing through the growth stages, while the majority look remarkably well, growth stages range hugely particularly in wheat, reflecting the extended sowing period throughout the autumn and winter months. Disease levels are variable with the more advanced crops showing higher levels of Rhynchosporium or Septoria.

Winter barley varies from awns appearing to heads fully out on the most advanced. Disease levels are generally low, with Rhyncho contained to the oldest leaves. However Ramularia is now appearing onto the upper leaves of some crops and this disease must be robustly controlled at the T2 timing along with Rhyncho, Net Blotch and Mildew.

 

 

Winter wheat crops range from those at 3rd node to flag leaf fully out. Septoria lingers on the lower leaves of all crops, and is rapidly moving up onto new growth in some. Yellow Rust has been found in recent weeks and surprisingly appearing in the variety Graham.

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).

Managing disease resistance and maintaining reliable control with the fungicide options available means using a range of different actives over the course of the growing season. Ensure there are a number of different modes of action are in the tank at every treatment, that way maximising the range of strains sensitive to the mix. SDHIs are now essential partners to protect the triazoles and maximise the yield in all but the most backward crops, adding some curative as well as preventative activity. Having a completely different mode of action to the triazoles, they will improve the kickback activity of the treatment, as well as widening the spectrum of disease strains controlled. It is good practise to use different actives from within the same chemical group at the different spray timings. Where possible, use different triazoles and SDHIs at each fungicide application over the course of the season to give the widest possible activity across the different strains of fungi of all diseases.

 

Time For Weed Control In Grassland

The last couple of weeks have offered some opportunity for farmers to get up to date with much needed fieldwork. As the season is racing on jobs are being done in less than ideal conditions. Grass growth has been slow due to low night time temperatures but chickweed has grown away through the winter and will need controlled especially in autumn reseeds. The presence of broad-leaved weeds will always take away from grass yield and quality. Docks and chickweed are nutrient loving weeds, thriving in nutrient rich regimes, ie more intensively managed swards. Docks have only 65% of the feed value of grass and are unpalatable to stock. Where infested swards are ensiled, their high nitrogen content adversely hampers a good fermentation, so leading to high pH silage that spoils quickly when opened and depresses intake. Dock seeds can also survive in silage and pass through the cow, infesting a field where slurry has been spread. The best defence against perennial broad-leaved weeds is to stop them establishing in the first place. This can be achieved by having a well-managed, dense sward, growing in well-structured non-compacted soil. Over or under-grazed leys that have been poached, offer perfect conditions for weed seeds to germinate. Topping or mowing weed plants provides short-term visual satisfaction but stimulates active regrowth – so the problem gets worse not better. The long-term solution for controlling persistent weeds in grass is to use modern systemic herbicides. A well-timed treatment with an appropriate herbicide can transform a weedy pasture into a productive ley, without the need for costly reseeding. Farmers may have to be more pro-active this year, as weeds have generally survived the mild wet winter, so weed numbers are much higher than usual. As many of our traditional herbicides have disappeared in recent years the good news is, this season we have now in our possession some very effective new armoury.

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 this 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 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 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.LEYSTAR 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.

To ensure a well fermented silage sufficient fertiliser must be applied at the correct time for intended cutting dates. On average allow one day’s growth for each 2-3 units of nitrogen between application and cutting. The younger the grasses the higher the feed value but the lower its yield. In general, aim to cut before 50% of the ears have emerged to gain as much yield as possible. Short chopping speeds up fermentation and aids consolidation ensuring not to cut too short as long fibre is required for rumen function. Where conditions allow fast wilting in good weather will increase the concentration of sugars and reduce effluent production.

WINTER CEREALS

The increases in temperatures over the last couple of weeks have made a marked impression on winter crops as they start to grow. Yellowing and patchy areas are becoming evident across fields as a result of localised variations in soil conditions varying the availability of N, P and K to the crop; wetter spots and compaction on headlands in particular are now showing up. Depending on when and if a T0 treatment was applied, diseases are prevalent in all fields. All have completed tillering, with the most forward approaching GS 33. Weed control should now be complete on both winter barley and winter wheat.

 
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