Crop Crack

For the latest guidance on oilseed rape crops this autumn, read the Corteva OSR update by clicking here. Topics covered include:

• Oilseed rape crop status and growth
• Weed control and herbicides use
• Starting to think about propyzamide for blackgrass or ryegrass control?
• Have you downloaded the Corteva Arable App to access Kerb Weather Data?
• Field observations and Corteva hotline key questions answered
• Give extra support to your oilseed rape crop by stabilising nitrogen in the Autumn
• Get the most out of our updates and be in with a chance of winning our monthly prize draw

The good spring continues, with little excuse for all fieldwork not being up to date. Ground conditions continue to be excellent, with silage being cut in ideal conditions, maize drilling and potato planting is now completed in most areas. Unfortunately for many waiting on the rain last weekend it amounted to very little and spring cereal crops are beginning to show signs of stress.

Potatoes

Where broad –leaved weed control has yet to be completed and the crop has passed the latest timing for Sencorex a reduced rate of Sencorex tank-mixed with Titus will provide a wider weed spectrum of weed control than Titus used alone and can be used on emerged crops up to 25cm high where the label allows. Scutch, other grasses or volunteer cereals are not controlled by the Titus/Sencorex mix. Where these weeds become a problem in coming weeks the graminicide Falcon can be used. Falcon can cause transient yellowing and is therefore not approved for use on seed crops. The first fungicide application should be made at the rosette stage or sooner if a blight warning has been issued. Potato farmers should be aware products containing metribuzin i.e Sencorex must be used up by 24^th November 2025.

Grassland

Grassland herbicides use growth function to kill weeds, therefore peak growth periods should be used for herbicide application. There must be sufficient growth to allow herbicides to be effective and vegetive growth is the key time to apply, as the chemical then gets drawn down into the roots. Herbicides are less successful once plants have progressed to the reproductive stage and have thrown a stem or began to seed. Once weeds are beyond the ideal growth stage for spraying, they should be mown or topped and allowed to regrow again, and a herbicide applied to the fresh young growth.

To optimise efficacy of any herbicide, recommended water volumes should be observed, even when it means more time spent spraying. It is important to note ragwort plants in their second year must be sprayed before flowering as flowering ragwort is poorly controlled. The routine herbicide treatments for this weed are Thrust, Lupo or 2, 4-D, and they are most active on growing rosettes with reduced activity as the stem starts to extend. They are not clover safe. Forefront is also very effective on ragwort. Stock must be kept off until the weeds have rotted away, which can take up to six weeks.

Buttercups are now ready for treatment. Best results are achieved if sprayed before flowering. ENVY is very effective on both buttercup and dandelions. Envy contains florasulam and fluroxypyr. Together they deliver excellent control of weeds found in pastures which typically get over grazed, receive minimal nitrogen or have poorly competing grass species present. Envy has no manure management restriction and has a short seven-day stock withdrawal period so animals can return quickly. Envy is very safe to grass and won’t hold back its growth. Buttercups are best controlled when they are still green and leafy and before the main flowering period. Envy will still give reasonable control even when the weed is flowering but for the best effect treat now. Product choice depends very much on which other weeds are being targeted.

Spring Cereals

The extended period of dry weather has allowed farmers to make significant progress on field work. For many growers it has been the earliest end to a spring planting season in a number of years.

Weed control has been difficult to date as crops are growing well but weeds are only just germinating due to the very dry conditions. 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. Whilst chickweed resistant to a wide range of herbicides is commonplace right across the province, the  inclusion of the active arylex into the herbicide tank-mix programmes in recent years has given improved control of  chickweed and other problem weeds including fumitory and sets a new benchmark in terms of weed control in spring barley and wheat. It belongs to a chemical family classified as synthetic auxins, similar to the old hormone chemistry and controls a wide range of broad-leaved weeds including those resistant to the ALS herbicides in most winter and spring cereals, including robust control of fumitory, fat-hen and ALS resistant chickweed. Marketed as ZYPAR, it is available in co-formulation with the active ingredient florasulam and has excellent multiway compatibility along with a very wide range of other pesticides and has no major following crop restrictions. It gives excellent control of a wide range of broad-leaved weeds that includes chickweed, fumitory, fat-hen, groundsel, brassica weeds, and cleavers, but its weakest weed is redshank. Whilst it will control it alone up to 6-leaf, when tank-mixed with ALLY MAX/RACING TF it will control redshank right up to flowering.

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.

 Nutrel Advert

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.

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 1^st 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 14^th 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 1^st and 2^nd 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

Growth regulation

When applied before 1^st 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 1^st-2^nd 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.

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.

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 2^nd 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.

Spring Cereals

Spring crops are looking very well and without the more usual effects of waterlogging seen in other years.  Although weeds are emerging fast as a result of last week’s rain, be sure all are well through before spraying. Also watch the size of the annual meadow grass if this weed is also to be controlled – efficacy falls off rapidly once it begins to tiller. 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 1^st 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. Sulfonylurea (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 spring cereals, ZYPAR will give excellent control of a wide range of weeds that will not be controlled by Ally on its own. These include chickweed, fumitory, fat-hen, groundsel, brassica weeds, and cleavers. It’s 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 SAXON are excellent tank-mix partners for this purpose.

Winter Cereals

Winter cereals have greened up well and are now racing through the growth stages. Awns are now out on almost all winter barley crops with growth regulator applications complete. The cool nights during April held back the crop response to nitrogen, but this has turned around and all nitrogen applications should be completed in the coming days to maximise green leaf development and crop yield.

Winter wheat crops which have not yet received T2 should be treated as soon as possible along with the growth regulator if required. The cool dry April and well timed T1 treatments have kept Septoria infection low, but it is present in all crops and remains a key focus for T2 treatments planning forward. Yellow Rust has been observed at low levels but perhaps a combination of cold nights and effective varietal resistance has meant that there have been no explosions of infection we were more familiar with other years.

Spring Cereals

Spring crops are looking very well and without the more usual effects of waterlogging seen in other years.  Although weeds are emerging fast as a result of last week’s rain, be sure all are well through before spraying. Also watch the size of the annual meadow grass if this weed is also to be controlled – efficacy falls off rapidly once it begins to tiller. 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 1^st 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. Sulfonylurea (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 spring cereals, ZYPAR will give excellent control of a wide range of weeds that will not be controlled by Ally on its own. These include chickweed, fumitory, fat-hen, groundsel, brassica weeds, and cleavers. It’s 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 SAXON are excellent tank-mix partners for this purpose.

Winter Cereals

Winter cereals have greened up well and are now racing through the growth stages. Awns are now out on almost all winter barley crops with growth regulator applications complete. The cool nights during April held back the crop response to nitrogen, but this has turned around and all nitrogen applications should be completed in the coming days to maximise green leaf development and crop yield.

Winter wheat crops which have not yet received T2 should be treated as soon as possible along with the growth regulator if required. The cool dry April and well timed T1 treatments have kept Septoria infection low, but it is present in all crops and remains a key focus for T2 treatments planning forward. Yellow Rust has been observed at low levels but perhaps a combination of cold nights and effective varietal resistance has meant that there have been no explosions of infection we were more familiar with other years.

A good start has been made to drilling spring crops, with the earliest drilled now emerging in the more forward areas. After a very mild winter, the colder temperatures during the first half of April slowed development in all winter crops, with many fields actually going backwards. The cold night-time temperatures have been very stressful to winter crops, hampering nutrient uptake causing purpling, yellowing and tipping of some leaves. However warmer temperatures and rain over the last week has improved everything, with all winter crops now looking much better. What is clear given current pricing it is more important than ever to optimise fertiliser applications to maximise the efficiency of utilisation of N, P and K. Soil pH is key – make sure this is above 6.2 for winter and spring crops. Granulated lime at around £125-135/t is excellent value and we should see a lot more of the granulated lime being applied to improve NPK utilisation. Correct use of foliar feeds also has an important role to play, where often it is not the amount of N applied that is the limiting factor, but perhaps sulphur or one of a number of micro-nutrients.

Growth regulation

The size of canopy at GS30-31 is a good indicator of future lodging risk, with larger canopies associated with greater lodging risk. Assess lodging risk on a field-by-field basis, also taking account of the field soil residual N and lodging history, and the varietal lodging resistance score. Numerous other factors contribute to crop lodging including sowing date, early growth over the winter months, and late season extreme weather events.

Against this background, a programmed approach made up of a number of treatments promoting shorter and stronger stems is essential. Plant growth regulator (PGR) choice, timings and rates all impact the outcome achieved. Early sown crops with thick canopies are most at risk of lodging, particularly if of a weaker strawed variety, and will require a more intensive programme to minimise the risk of lodging

Fungicide update

With a better understanding of disease resistance to single-site triazole, SDHI and strobilurin chemistry, maintaining the efficacy of this chemistry is critical to being able to continue to control wheat and barley diseases effectively. Multi-site chemistry is key to prolonging the efficacy of the single-site chemistry. Chlorothalonil (CTL) was the mainstay of multi-site activity for years, but with its loss two seasons ago now, folpet, available from Syngenta as MIRROR is regarded as the most effective replacement.

Folpet is a multi-site active, and all manufacturers are advocating the inclusion of this active into wheat and barley programmes, not only to prolonging the single-site actives, but to improve disease control also. Its inclusion improves Septoria activity in wheat and gives some improvement of Ramularia in barley. Like CTL, folpet is a contact ingredient only with no systemic activity, protecting the surface of the leaf by preventing the fungal spores germinating on the surface of the leaf.

Early weed control – Annual Meadow Grass In Spring Crops

If Annual Meadow Grass (AMG) is to be controlled in spring crops, this must be done as soon as possible. This will be done before the timing for controlling broad-leaved weeds (BLW) in spring cereals. There are a number of product options, but all must be applied either pre-emergent or in the case of one, very early post-emergent of the crop.

Applied pre-emergent, all work by residual activity to control the AMG. Since residual herbicides require sufficient soil moisture to be effective, so their performance will be compromised in drier soils. This is the primary reason for the variable performance of AMG control achieved in the spring. Best control is achieved when applied onto a damp seedbed, keeping the water volume up and travelling slowly. To maximise efficacy and crop safety, ensure the label guidelines are strictly followed.

The last couple of weeks have offered a good opportunity for farmers to get up to date with much needed fieldwork. 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 winter and kind spring, so weed numbers are much higher than usual.

DOCKS

As thoughts turn to silage, treating dock-ridden leys with DOXSTAR PRO or PIVOTAL 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 and HALCYON are the most effective herbicides available to grassland farmers for the control of docks, ragwort, chickweed, thistles, dandelions, nettles and buttercups. Both have long lasting weed control to date with a single well-timed spray giving up to 18 months control so whilst they 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, HALCYON, DOXSTAR PRO,PIVOTAL 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 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 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 and LEYSTAR will be used widely on new sown leys this season where clover is not important. These will control both strains of chickweed.

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.