Crop Crack

Winter Wheat

All T2 fungicide applications onto winter wheat should now be complete.  Winter wheat crops moved at exceptional pace during the dry warm period a few weeks ago with some crops missing the growth regulator as ears emerged overnight. Aphid numbers had increased significantly during the dry warm spell also, but the recent rain will have washed them down the stem hence slowing their colonisation further up the plant.  Growers need to continue checking crops right up to milky ripe stage and spray if present in numbers. Unnecessary insecticide applications should not be applied as most are not bee friendly.  Of the aphicides approved for use for this purpose, Sumi-Alpha is the safest to bees.

Spring Barley

All weed control should now have been carried out on spring barley crops, and all should now have received the T1 fungicide application. The two most dominant diseases in our climate are powdery mildew and rhynchosporium with ramularia becoming an increasing problem over recent years.  Ramularia can be difficult to identify but unlike most other physiological leaf spots which are only visible on the upper side of the leaf ramularia is easily seen both on the upper and lower surface of the leaf and the longitudinal edges of the brown lesions remain enclosed by the leaf ridges. Symptoms appear where crops are subjected to stress from alternating periods of wet weather & sunshine, or man-made as a result of scorching.  Chlorothalonil (BRAVO) is very effective when used preventatively, helping to maintain green leaf area when used along with a triazole/strob mixture.

All weed and disease control should now be complete on both spring wheat and oats.

Grassland

Although it looked very grim a few weeks ago grass crops yielded very well and for most the quality was excellent. Attention must now be given to those fields which were not sprayed prior to first cut.  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 vegetative 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 are now coming close to flower and should be sprayed immediately as flowering ragwort is poorly controlled.  The routine herbicide treatments for this weed are full rate MCPA 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. You can use a mixture of both these products as Nufarm Lupo which allows an increased dose herbicide compared with either alone, with a consequent activity benefit. 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.

Potatoes

The protracted planting this spring has meant some potato crops have yet to receive weed control.  This task must take priority as to delay until after crop emergence will set the crop back even further in an already late season. Conditions have been ideal for the use of residual products (Afalon,Linurex,Sencorex).  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 Shogun can be used. Shogun can cause transient yellowing and is therefore not approved for use on seed crops.

As canopies close, the soil surface will tend to remain damper, encouraging slugs onto the soil surface. Timing is critical for effective control, just before the crop meets across the rows. Take advantage of any rainfall by applying pellets just afterwards, as this will bring slugs up onto the soil surface. Potato varieties particularly susceptible to slug damage include Maris Piper ,Desiree and Kerrs Pinks.

Blight fungicides move through the plant in three different ways contact, translaminar and systemic.  Dithane,Ranman Top, Shirlan and Tizca are all contact fungicides. These Products protect only the outer surface of the leaf onto which they are deposited.  Translaminar products such as Curzate M, Invader, Resplend and Revus move into the leaf and redistribute throughout the leaf tissue as it increases in size whilst systemic products such as Consento, Fubol Gold  and Infinito move in through the leaf surface and upwards into the new growth protecting this from infection also.

Products with zoospore activity are the most effective 1^st spray, applied at the rosette stage prior to rapid haulm growth. Shirlan or Tizca will control any zoospores that may be in the soil and provide good protection of the new plant. During the main canopy development phase with the considerable amount of new growth it is essential the product being used is fully systemic to properly protect the new leaves being put on between applications.  Later planted crops are higher risk as they produce more new growth between applications than earlier drilled crops, at a time when the level of inoculum in the air is progressively increasing.  If spraying during periods of unsettled weather, rainfastness of all products will be further improved with the addition of a sticker to the spray solution.  Guard is a latex sticker and will improve the retention of the fungicide onto leaf surface, so improving both adhesion onto the leaf immediately post application and over the following days should rainfall levels remain high. The way the blight product is applied is as important as the product choice.  Make sure nozzle type used is correct to ensure sprayer pressure, droplet size and water volume  applied, is as directed on the label.  Inspect and calibrate nozzles regularly to maintain performance. Never use any blight product at reduced rates.  Do not spray when the leaves are wet as this will significantly increase the likelihood of runoff.

Temperatures over the last week were certainly what you would expect for early June, yet we have almost accepted there is no such thing as the norm anymore. Sprayers have been busy this week but care must be taken not to spray in strong sunlight. It has been very frustrating for farmers trying to grab any available opportunity to spray crops; it was too wet, too windy and now too hot!  Any weed control onto potatoes and veg should be delayed as drier conditions remain and residual herbicides require moisture to work effectively. Many farmers have been at silage this week with crops bulking out very well.

SPRING CEREALS

The above average rainfall over winter has depleted many soils and it is essential to replace essential nutrients. Spring barley crops grown on low PH soils with a low P index seem to be struggling most this season. This must be rectified with lime and Phosphate fertilizer in accordance with soil analysis. Leather jacket damage is still occurring in later drilled crops and should continue to be monitored. This pest coupled with poor germination of seed due to cool soils has left many bare patches in fields at present.

An application of a balanced and rapidly available source of macro & micronutrients at this key time will minimise the adverse effects of restricted soil nutrient uptake. CEREAL HIGH N supplies 3.7%Mn, 1.5%Mg, 1.8%Cu, and 0.6% Zn in the most rapidly available form to plant through the leaf and also supplies high levels of Nitrogen and Sulphur.  Potash deficiency is also showing up in many spring barley crops with pale green yellow tips being the first symptom.  Deficency is most likely on light sandy soils or in crops following intensive grassland. Manganese deficiency is also appearing on crops especially where lime has been applied recently.  A foliar application may be applied along with the weed control.

To minimise the effects of competition on the crop and optimise the level of weed-control, herbicide application should be carried out at the earliest opportunity, once all the weeds have emerged but are still small, and before they begin to compete with the crop for nutrients and light. With low soil temperatures since drilling, weeds are not coming through as rapidly as expected but chickweed is beginning to choke out young plants and must be sprayed as soon as possible.

Product choice will depend on the weed type and size present and the crop growth stage.  Broad-leaved wise, Sulfonyl-urea (SU) herbicides will likely be the starting point, controlling a wide range of weeds and very safe to the crop.  Options include ALLY MAX covering a wide spectrum of BLW with the max formulation giving improved control of polygonums & other BLW over the old ALLY formulation.  HARMONY M SX controls a wide range of BLW at sizes larger than any other sulfonyl-urea herbicide.  HUSSAR is being used on spring barley to control grass weeds, however this must always be tank-mixed with another BLW herbicide to control SU resistant weeds (chickweed) and those weeds not controlled by the SU’s (cleavers, fumitory& fat-hen).  Ideal partners are COMPITOX controlling chickweed, fat-hen & fumitory, or OXYTRIL CM controlling field-pansy, red dead-nettle and speedwells and SPITFIRE /MINSTRELfor chickweed and cleavers.

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, sulphonyl-ureas products will improve control.  AXIAL gives excellent control of wild and tame oats in spring barley and spring wheat and has an excellent window of opportunity.  Application should be held off until at least 6 weeks after drilling to ensure all wild oats have germinated. It can then be applied up to full flag-leaf of the crop and full flag leaf of the wild oatGS39, allowing a minimum of 21 days to have elapsed after application of the BLW herbicide. The wetter ADIGOR must be used in all situations along with the AXIAL.

WINTER WHEAT

Most crops are now moving through the stages of stem elongation with more forward crops at flag leaf.  Septoria tritici is present in most crops at variable levels depending on T1 timing but with recent weather; expect levels to rise if fungicide rates and timings are not correct.

As the flag leaf will be emerging in most crops within the next week or two it is the key time to apply the T2 treatment. Of all fungicide treatments, T2 has the greatest impact and response in terms of grain yield and quality, keeping the top three leaves clean and the ear as it emerges. The dose rate applied must be sufficiently robust to ensure long term protection of the flag leaf plus eradicate disease already present on the lower two leaves that also contribute to yield. Prothioconazole in PROSARO or BRUTUS (epoxiconazole + metconazole) will form the key part of the T2 fungicide onto winter wheat.  Growth regulator must also be applied at this time where required.

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.