Wendy Fearon

The prolonged period of cold weather over recent weeks had restricted growth of all spring and winter sown crops. Whilst all germinated well, growth of most crops has been particularly slow. Rainfall has been adequate, enough to maintain good soil moisture ensuring even germination of crop and weeds, but surprisingly not too much to cause any transient yellowing associated with plants struggling to take up nutrients in waterlogged soils.

The problem was very much the lack of heat, restricting nutrient availability and therefore growth and development. To date aphids have been discouraged from flying due to cool conditions but this can quickly change as temperatures improve.

The well below average air temperatures up until now mean soil temperatures have also been well below average for the time of year. The Nitrogen mineralisation process in the soil where fertiliser nitrogen is converted to a form that can be taken up by the crop is a soil microbe process and therefore dependant on soil temperature. Hence colder soil has slowed the availability of nitrogen to the crop, and many other nutrients also, particularly manganese. Many crops are beginning to show nutrient deficiencies as a result.

The application of a broad-spectrum trace-element mix along with key macronutrients at this time is a very useful and beneficial way to supplement the plant’s nutrient requirements during periods of restricted availability, especially when coinciding with phases of rapid growth ie during tillering and as stem extension begins. An application of a balanced and readily available source of macro & micronutrients that is not dependant on soil availability at this key time will minimise the adverse effects of restricted soil nutrient uptake.

Spring Cereals

To minimise the effects of competition on the crop and optimise the level of weed-control, the herbicide application should be carried out sooner rather than later, once all the 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 at the 2-4 leaf stage will lower rates of herbicide and give a much more effective result than delaying to coincide with the 1^st fungicide application.

Product choice depends on the weed type and size present and crop growth stage.

Broad leaved wise, Sulfonyl-urea (SU) herbicides will likely be the starting point, controlling a wide range of weeds and are very safe to the crop.

Where the range of BLWs present are limited to chickweed, redshank, fat hen, fumitory & day nettle, the hormone mixture products will work well without the need to tank-mix, but must be applied by GS31. Where the likes of field pansy, forget-me-not, speedwells & corn-marigold are also present however, sulphonyl-urea products will improve control. Grass weeds are commonplace this season especially on head rigs, HUSSAR is the most popular  product  available to treat AMG in spring crops, controlling it up to the end of tillering. It also gives very useful suppression of wild oats that are emerged at the time of application (further plants are likely to emerge later). It also controls a range of BLW very similar to the other SU’s.

If clover is part of the mixture, a clover safe product must be used. TRIAD is a new clover-safe herbicide now in its third season.TRIAD is very effective on chickweed. If seedling docks, thistles and buttercup are also problem weeds, SPRUCE must be added to the TRIAD to improve control of these also. SPRUCE is 2,4DB, a clover safe hormone type herbicide.

Winter Barley

Growth stages in cereals are hugely influenced by day length. Now into the third week of May, the longer days are driving ear development, and with it ear emergence. The most advanced fields are at flag leaf emerging, GS37-39. Awns emerging, GS50 is only days away in these crops – once at this stage it will be too late to apply any growth regulator.  It is critical to assess crops now to check if a growth regulator is required.

In many cases the T1 fungicide may have only been applied in the last 10-14 days, with the T2 application not due for another couple of weeks yet. However to hold off and apply the growth regulator with the T2 fungicide will be too late for most crops, as in all likelihood the awns will be showing by this time.

Rhyncho is present in most crops at various levels depending on the disease control already applied. The cool and damp weather pattern over the last month has been ideal for this disease, and without a robust and properly timed fungicide application this disease will move rapidly up the plant onto the upper leaves, awns and heads. Ramularia is also beginning to show, with newer varieties showing greater sensitivity to this late developing disease. It tends to show late in the season usually after booting, symptoms are very similar to manganese deficiency.

Winter Wheat

Most crops have now moved through the stages of stem elongation.  Septoria tritici is present in all crops at variable levels depending on T1 timing. Winter wheat crops are at varying growth stages

The flag leaf will be emerging in most crops within the next week or two, and this is the key time to apply the T2 treatment. Of all fungicide treatments, T2 gives the greatest response in terms of grain yield and quality, keeping the top three leaves clean and the ear as it emerges. For this reason the manufacturers are targeting their new SDHI chemistry at this timing when the big spend will give the greatest return. Trial work on both sides of the Irish Sea last year showed consistently higher yields when these products were applied at this time.

While not as curative as the triazoles, each manufacturer claims extended persistency against Septoria for their SDHI actives. Co-formulated with triazoles, they all show excellent Septoria activity as well as extended activity on rusts and in the absence of disease enhance green leaf retention (similar to strob activity), so boosting grain-fill. Whilst their disease performance is not enhanced by the addition of a strob or chlorothalonil at this timing, from a disease resistance management point of view chlorothalonil should continue to be added.

Grassland

As fodder reserves are now almost depleted on many farms attention is now on getting as much grass into the clamp as possible. Where grass is still not ready for first cut there may still be the opportunity to treat docks and other problem weeds. DOXSTAR, PASTOR and FOREFRONT are all very safe to the grass. Losses in grass yield often go unnoticed because farming practice tends to focus on livestock output rather than the actual output of the grass. The productive capacity of grassland depends on a large number of factors but in the main is dependent upon the climate and the soil. Mild temperate weather with deep rich soils is the most favourable. Other factors such as the topography of the land, species mix, and sward damage can be important, but generally to a lesser extent.  Weed infestations can impact significantly on the yield and quality of grass for both grazing and cutting with trial work confirming a 10% weed infestation will cause a 10%yield loss. FOREFRONT is the most effective herbicide available to grassland farmers for the control of docks, 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 control up to 18 months so whilst it may appear expensive it really is good value for money.

This has certainly been a very changeable week with wintry showers, high winds but most importantly increased temperatures. Many crops are under stress and care should be taken not to rush out and spray these where timing is not crucial.

Cereals

Manganese deficiency is now commonplace in many crops, symptoms showing more in continuous cereal ground and ground recently limed. Symptoms begin with small pale green speckles appearing throughout the leaf and these will progress to turn brown unless treated.  Copper deficiency often accompanies Manganese deficiency – it’s 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 as soon as symptoms are seen.

Othello and Bio Power are now the best option for weed control in winter wheat only.  These actives are contact only and therefore need the grass to be completely emerged and growing actively, and are very effective on larger annual meadow grass. In addition they also have activity on a range of broad-leaved weeds.

Spitfire is now in its third season and has given excellent weed control over the last couple of years. It contains two active ingredients, a high loading of the sulfonyl-urea (SU) florasulam, and fluroxypyr. It controls a very wide spectrum of weeds including chickweed, cleavers, black bindweed, charlock, knotgrass, mayweeds and volunteer rape, and an equally wide window for application in all cereal crops. It can be used from 3-leaf of the crop GS13 right up to GS45 in winter wheat and winter barley; up to GS39 in spring wheat and barley; and up to GS31 in winter and spring oats, winter rye and triticale.

Wild oats will continue to emerge in later drilled winter crops for another few weeks yet, so delay application until certain that all have emerged. 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 any antagonism, a minimum time interval must elapse between application of the BLW herbicide application and this application. The time has now passed to treat grass weeds in winter barley. Once spring growth commences properly contact herbicides give more reliable control, but their efficacy is critically linked to improving soil temperatures and active weed growth having begun.

Growth Regulation and Managing Thin Crops

When applied early enough in the plant development, application of certain chlormequat growth regulators can significantly increase tiller numbers. Both ADJUST and SELON work 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. The biggest yield responses to this early application are seen in thin crops, as most crops are this season.

Timing is critical to maximise this effect. 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 however it is too late to affect tiller numbers and survival, primarily only serving to stiffen the stem at this time. The earlier it is applied during tiller development the greater the tillering 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.

Potatoes

Maincrop potatoes are currently being planted in pockets across the province. Drills are moist and with a bit of heat hopefully to come, will encourage rapid emergence of crop and weeds. Therefore growers should be planning weed control now, taking good advantage from the moist soil conditions.

Most weed control programs are based on residual products i.e. products that are taken up through the soil, and are therefore very dependent on sufficient soil moisture to work effectively. Soil conditions are ideal therefore at the moment, moist enough on the tops of the drills to allow the herbicide be taken into the soil and taken up by the germinating weeds.

Grassland

With stocks of silage very low and a late start to the season there is a need to maximize grass yields for grazing and silage this year.  With very high feed prices it has never been more important to get the most from your grass.  Grazed grass is the cheapest feed on your farm.  However yields can be very severely impacted by weed infestation.  With conacre prices higher this year, farmers need to maximize the potential on their own land before deciding to rent what could be expensive ground.  Weed control can run from as little as £6.00 up to £20 per acre depending on target weeds.  This expenditure will not rent a lot of land but can make a huge impact on grass yields on your farm.

As much of the of the grassland acreage went untreated for weeds last year it is important to inspect fields intended for cutting and grazing in order to allow the spray interval for stock rotation. Grass growth to date has been very poor but hopefully with the heat this week, growth will improve.

It is important to allow one days growth for each 2-3 units of nitrogen between application and cutting to achieve good quality feed. Failure to use up the fertiliser applied may result in poor fermentation due to high levels of non-protein nitrogen in the crop.

Docks are the most damaging weed which infests Northern Ireland farms. Part of the reason for the success of docks is that they will germinate and grow in almost any situation, and can then multiply by seed production or from underground roots. Seeds can be spread by a variety of means such as wind, water, stock and machinery. In most grassland fields there are approximately 12.5 million dock seeds per hectare in the top 15cm of soil and these can remain viable for up to 80 years. This seed bank provides an enormous reserve for re-infestation and reinforces the message that weed control is an ongoing battle not a one-off measure. It is important to remember that grassland herbicides are only effective when grass and weeds are growing actively and should not be used when there is a risk of low night temperatures.  Over the last 5 years Forefront has been the outstanding product for controlling docks in Northern Ireland.  In addition to docks it will also control nettles, thistles, buttercups, ragwort and chickweed giving a complete clean-up in your fields.

With many fields showing the effects of the last couple of wet years, rushes have become a major issue on farms in Northern Ireland. Rushes are relatively easy and inexpensive to control.  Spray rushes when they are green and actively growing, and always add a wetter/sticker(e.g. Activator) to enhance uptake into the plant.  Due to the shape of the rush, there is always potential for spray run-off, which the wetter will help to prevent.  The most popular products for controlling rushes in Northern Ireland include Agritox and Spear.

Many of us witnessed horrendous weather conditions over last weekend and any urgency to tend crops has been further delayed. Both grass weeds and broad leaved weeds are appearing in crops which did not receive an autumn herbicide. Wheat crops are still showing low levels of disease whilst most winter barley crops have a fair bit of foliar disease on older leaves.

Cereals

Much of the later drilled winter cereal crop did not receive a residual herbicide. As temperatures rise clods will be broken down on both treated and untreated crops requiring a herbicide treatment. Those wheat crops not treated in the autumn can be treated with OTHELLO and BIOPOWER up to GS32 of the crop. Applications should be made when temperatures are good and both the crop and weeds are actively growing. OTHELLO will give good control on chickweed, pansy, speedwells, charlock, groundsel and most importantly annual meadow grass. I have spotted a few wild oats over the last week but it is important to note they will continue to emerge over the coming weeks and treatment should be delayed until all of the wild oats have emerged. AXIAL and ADIGOR can be applied from GS11 up to GS39 on both wheat and barley. Where weed control is required a 7 day interval must occur from the time of spraying Axial before applying sulfonyl urea or hormone herbicides. If these products are applied first then a 21 day interval must be observed before applying Axial.

Preparing For Spring Crops

Land intended for spring cereals should be sprayed off with glyphosate as ground conditions allow. Roundup Energy is still the best value for money in the glyphosate market with all its additional benefits over generics. Roundup Energy has faster uptake and greater consistency in a wider range of weather conditions. It is important to remember when comparing glyphosate prices the amount of active it contains, Roundup energy contains 450gm/l compared to 360gm/l in most other glyphosate.

The slight increase in day time temperature over the last week will encourage pests such as wireworm, slugs and leatherjackets to resume feeding and should be closely monitored. Surveys carried out recently show leatherjacket numbers are significantly higher than spring 2012.Pre ploughing treatments with Dursban or Cyren are more effective than those applied once any damage is under way in the spring-sown crop.

Disease Control

In our climate maximising yield means controlling disease effectively. Getting timings right is absolutely essential; ‘fire-brigade’ control of disease is more costly and a lot less effective than well timed preventative control.  Except in very low disease pressure conditions, it is a false economy to skimp on disease control and get away with it – all independent work shows that increasing fungicide doses does also increase yield.

Manganese deficiency is now commonplace in many crops, symptoms showing as growth gathers pace. 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 as soon as symptoms are seen.

I am amazed at the extent of damage in both winter cereal crops and grassland from leatherjackets already this season. Leatherjackets are the larvae of the crane fly or ‘daddy long legs’ and cause widespread damage to cereals, grassland, root crops and vegetables. Eggs are laid in the early autumn, and the larvae hatch and feed over the winter period.

Leatherjacket numbers are much higher this spring than they have been for many years. Where fields are looking poor or yellow, or bare patches have appeared, it is essential to inspect for leatherjackets. Damage is already becoming apparent in some established grass swards. With this evidence of high leatherjacket populations, spring cereals are also certain to be at risk, especially those following a grass ley. As crops are most susceptible to damage at the seedling stage it is most important to monitor leatherjacket numbers from emergence onwards.

In newly sown cereals the need for treatment is assessed by scratching along 30cm (12“) drill lengths to a depth of 5cm and searching for leatherjackets. The following grub numbers are the threshhold figures at which damage is likely to occur: -permanent pasture-100/m2 -spring cereals -50/m2 Young cereals are attacked both below and above the ground. To limit damage leatherjackets need to be detected before they have had a chance to do serious damage to your crops. A good early indicator of high populations is the presence of birds, in particular rooks, crows and starlings, in fields as they search for the grubs. Symptoms of leatherjacket damage are yellow dead plants or withered patches of grass that have been cut off from their roots just below the ground. On closer examination leatherjackets can be found by digging in the top 2-3 cm of the soil. At this time of year they are typically 1-2 cm in length grey in colour with a tough leathery coat, hence their name, and resemble a large maggot.

If numbers meet the threshold, chemical treatment should be applied using a product containing chlorpyrifos such as DURSBAN WG or CYREN. As the leatherjackets live in the soil the spray must reach the soil therefore a high water volume (500l/ha) is essential and a coarse spray quality to ensure good penetration into the soil surface. Light rain after the spray application will also help.

DursbanWG at 1.0kg per hectare gives the highest level of control of leatherjackets as it is strongly absorbed onto the clay particles in soil persisting for up to 6-8 weeks.  Dursban’s unique formulation is based on a novel free-flowing granule containing 75% chlorpyrifos – the most concentrated active ingredient loading of any chlorpyrifos product. It is important to note when using an induction hopper a continuous flow of water through the hopper must be maintained. The sprayer should be half full before adding Dursban to the tank.  When using a filter basket this must be removed and the Dursban WG added to the tank in a steady even flow maintaining agitation.

Chlorpyrifos is judged to be non injurious to birds and, at dose rates likely to result from commercial applications, little or no effect has been detected on overall populations of soil fungi, bacteria or algae.Dursban has also been shown to have little effect on earthworms and other beneficial arthropods.

The drier conditions over the last week have been a welcome sight. Winter cereal crops on the whole have struggled with the persistent wet conditions since drilling. Many crops have also been decimated by slugs over the winter and more recently leatherjacket numbers have rocketed. Hopefully all crops have received their autumn herbicide for the control of broad leaved weeds and annual meadow grass but there is still an opportunity to apply residual herbicides to late drilled crops. Othello is still an option going into the spring for grass weed control where the grass has begun to tiller (on winter wheat only). Most crops are now beginning to seek fertiliser and now is the time to assess which fertiliser is to be applied according to the soil analysis. Cereal pricing still remains strong but this is overshadowed by the rising cost of fertiliser and other essential commodities to grow crops. It is more important than ever to carry out soil samples with soils of index 3 for P&K being the optimum level for agricultural land. I feel there is still not enough emphasis put on the importance of PH levels in the soil. Where ph is low the soil is unable to utilise the nutrients in the fertiliser, ph of 6.5 is ideal to grow cereal crops with 6.0 being more suited to potato crops.Landscapers have been working away through all the wet weather but pruning and other work has been difficult with current ground conditions. Unfortunately with the extreme weather conditions experienced over this winter many trees and shrubs have died and will need replacing.

Winter is the best time to control weeds around young hedges and trees. Season long control of grasses and most broad-leaved weeds is possible by applying Kerb Granules at this time. Kerb is a pre- and post-emergence residual herbicide that provides selective, broad spectrum weed control.

Kerb can be applied to all soil types, therefore allowing its use in many areas where weed control is needed. Kerb is the ideal herbicide for forestry and woodland (including farm forestry), ornamental shrubberies and rose beds, hedges, fence lines and gravel pathways.

Agrochemicals and fertilisers are major variable inputs in growing crops and the way they are applied has a great influence on their efficacy.

It is essential therefore that the equipment used to apply them is well maintained and accurate.

Sprayers should be calibrated regularly. One of the most important areas of the sprayer is the nozzle. Nozzle output should be measured to check that it is the same as the value in the calibration chart for that type of nozzle. Nozzles with a variation of more than 5% should be changed.

Money spent maintaining the sprayer is money well spent as a properly calibrated sprayer will reduce wastage of agrochemicals and will improve their performance.

Similarly fertiliser sowers should be calibrated and if possible get a tray test carried out to check the spread pattern as striping in crops is often caused by uneven fertilizer application, which again wastes money.