Crop Crack

Still Time For Dock Control In Silage Ground

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.

 

Spraying Slow To Get Going This Spring

Welcome to the first crop crack of 2024 and for the first time in many months we look set to get at least a few settled days. Growth is not what we would expect for the middle of April, and it is important to note that stress in whichever form will affect nitrogen utilisation. Nevertheless, top dressings are kicking in and crops are starting to come away. The poor economics across the agri-sector coupled with the persistent bad weather conditions have left a very depressive mood amongst many of the farmers I have been speaking to in recent weeks.

Winter Barley GS30 – GS31

All crops have completed tillering, with the most forward fields past 1st node, GS31. Most are looking well considering the wet conditions over the winter. There are good plant counts and tiller numbers, but the mild winter means disease is already well established on these young plants with Rhyncho, mildew and net blotch showing in all.  Rhyncho remains the most damaging disease of barley, seriously damaging yield potential if not controlled quickly and effectively.

Winter Wheat GS22 – GS31

Growth stages vary widely depending on drilling date, but most are at various stages of tillering. Most have reasonably good plant numbers but some fields have suffered from waterlogging and unfortunately stitching in, up until now has been impossible. Septoria is established in all crops but particularly so in earlier drilled fields.

Disease Control

Rhynchosporium and Septoria are the two most damaging cereal diseases in NI. Both have always been more effectively controlled preventatively, but in previous times the curative properties of the azole family were able to rescue a bad situation, particularly in wheat, this is no longer the case.

Timing of fungicide applications and rates used are every bit as critical as product choice to achieve the maximum potential response. To ensure the main disease programme persists right through to ripening, it is advisable that all crops should by now have received a T0 fungicide where conditions have allowed. Farmers should be aiming to apply their main T1 fungicide application within the next week or so. Due to ground conditions to date, very few T0 sprays have actually been applied. Depending on crop stage, there may still be a good case for a T0 treatment. A T0 sets up a cleaner crop for its T1 treatment, which in turn can then can be less dependent on curative performance and more on preventative. Teagasc trials last year looking at the benefit of a late applied T0 were striking. They compared a very strong T1 + T2 programme with and without a T0.  The T0 application of full rate THIOPRON + half rate COMET (applied on 14th April 2023 at GS31, just 11days before the main T1 went on), gave a significantly cleaner crop at flag leaf, which went on to translate through to more than a 0.5t/ha yield improvement in wheat.

T2 and T3 applications following at 4-5week intervals, ie mid-May and mid-June. This T1 timing should coincide with the beginning of stem extension between 1st and 2nd node, GS31-32.

Holding the T1 timing to GS31-32 should ensure T2 in barley and T2 & T3 in wheat be optimally timed to avoid extended gaps, maintaining persistency right up to and during senescence. Where a crop has not received a T0 treatment product rate at T1 will need to be increased to take account of this.

Weed control

Many crops did not receive an autumn herbicide and for those still to be treated, control of Annual Meadow Grass (AMG) is the most pressing issue. HAMLET is an excellent option for AMG in wheat only, there is no similar late option for barley. Note that HAMLET will only control AMG that has already emerged; unlike the autumn products it has no pre-emergent activity. Where the AMG has been controlled in the autumn but for example chickweed, cleavers or groundsel are likely to be a problem, ZYPAR is an excellent stand-alone broad-spectrum herbicide controlling these and most other emerged BLW. It also works best when the weeds are growing actively and has post-em activity only, therefore delay use until all cleavers have germinated and temperatures have risen to encourage growth. ZYPAR is also an excellent tank-mix partner with HAMLET

Hamlet

Growth regulation

When applied before 1st node, GS31, application of certain chlormequat growth regulators can significantly increase tiller numbers. Chlormequat works by suppressing apical dominance, ie main stem development. In doing so it diverts the plant’s resources into producing and supporting more tillers. Particularly in wheat but in barley also, more tillers will go a long way towards compensating for low plant counts, ultimately increasing yield.

Correct timing is critical to maximise this effect. The earlier it is applied during tillering the greater the tiller effect, but note early application to increase tiller numbers will also reduce its effect on lodging. Application of a chlormequat based growth regulator often goes on with a T1 fungicide application sometime around 1st-2nd node, GS31-32. At this timing it is too late to affect tiller numbers and survival but will maximise the stem stiffening effect.

Early application will also increase root growth and so reduce stem-base lodging. Stem-base lodging is where the plant folds over at the soil surface as a result of poor anchorage in the soil, and is caused by poor root ball development, more likely when the seedling develops in wet soils that limit root development. All winter crops have rooted very shallow this season as a result of the persistently wet conditions and therefore stem-base lodging is likely to be a significant problem later this season.

Nutrient Deficiency

A combination of waterlogged soils, plants already suffering from restricted nutrient uptake and plants now trying to grow, is showing up Mn deficiency in many barley crops. Continuous cereal ground and ground recently limed is most prone to deficiency. Symptoms begin with small pale green speckles appearing throughout the leaf and these will progress to turn brown unless treated.

Copper deficiency often accompanies Mn deficiency – its symptoms are complete browning of the leaf tip especially the youngest leaves, and apparent wilting of the plant. Treatment will be most effective if treated immediately symptoms are recognised.

With air quality significantly improving over the last two decades, the most important source of sulphur to the soil coming from the pollutant gas sulphur dioxide has also reduced significantly. Whilst its deficiency is now being recognised and corrected on grassland through the application of high sulphur compound fertilisers, its impact in cereal crops in NI has by and large been misidentified or overlooked. After nitrogen, phosphate and potash, sulphur is the next most important element required by all crops, used to make essential sulphur containing amino acids and proteins in all plants. Soil sulphur is easily leached especially from light to medium soils, making shallow-rooting plants particularly vulnerable to deficiency. Deficiency causes paling in the cereal plant, caused by a reduction in chlorophyll production and even in the absence of any symptoms, decreased efficiency of nitrogen utilisation. Whilst often mistaken for lack of nitrogen, sulphur is not very mobile within the crop and therefore deficiency is most pronounced on the younger leaves; the opposite to nitrogen deficiency which affects the oldest leaves first. Crops of both wheat and barley with high yield potential are particularly responsive to one to two applications of foliar sulphur at the timings of rapid growth.

Nutrel Advert
 

Spring Crops Growing Rapidly

The catchy weather in April and early May has meant Septoria pressure has been extremely high especially on those earlier drilled winter wheat crops. The ear has now emerged on many crops of Extase and mildew is present on the more forward lush crops of Graham. Aphid numbers are currently very high in both winter and spring cereals. Any late drilled spring barley should be inspected and if colonies are found on over 50% of plants it should be treated to reduce the risk of BYDV.

Most spring cereal crops continue to benefit from the recent improved temperatures with many now racing through the growth stages.

Zypar Strapline

Crop Nutrition

As soils warm up and daylight hours are considerably longer the likelihood of crop stress through too little moisture, or not enough nutrient availability to support the potential rate of growth is now showing up in later drilled crops. 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 manganese 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. 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, 38gm Mg, 45gm Cu and 15gm Zn per hectare.

Fungicide Timing

The T1 application should be applied from late tillering to the start of stem extension, GS24-31. Since this treatment is primarily for insurance and the risk of infection being present at this time is low, it follows that rates can be reduced compared to the winter crop. The T2 is the more responsive timing in spring barley when Ramularia is also a significant risk, therefore more of the spend should be directed at the T2 timing. This application should be applied from first awns visible to ear completely emerged, GS49-59. Also bear in mind too that preventing Rhyncho infection is much more effective than trying to control it curatively. Once infection has come in, any eradicant treatment has limited efficacy, and the infection will stress the crop, increasing the risk of Ramularia infection sooner rather than later.

 

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 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/CRATUS 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.

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.

 
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