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T1 Fungicides on Winter Crops – Weed Control in Spring Barley

The prolonged period of cold weather over recent weeks had restricted growth of all spring crops sown in late March. Whilst all germinated well, growth of most crops had been particularly slow. Rainfall has been adequate, enough to maintain good soil moisture ensuring even germination of crop and weeds, and 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. The pleasant rise in temperature this week has encouraged both weeds and crops to move rapidly. To date aphids have been discouraged from flying due to cool conditions but this will have changed this week with the sudden increase in temperature.

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 1st 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-ureas products will improve control. Conditions over the last week have been ideal for hormone products with consistent day and night temperatures. Compitox, Minstrel and Oxytril are the most widely used tank mix partners with SU’s.

Grass weeds are commonplace this season especially on head rigs, HUSSAR is the only product now 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 available for the first time last season. Whilst currently labelled for use in ‘Spring Barley undersown with IRG’ only, a new wider label is currently going through the approval process reading ‘Spring Barley undersown with grass, and grassland’. 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

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. Mildew is also present at varying levels. 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.

The SDHI chemistry now available have a good position at T2 on winter barley crops where they retain green leaf and are very active against Ramularia. However whilst Bixafen (Bayer) and xemium (BASF) have curative activity, triazoles are still essential to the core of the T2 fungicide mix, with prothio, epoxi and flusilazole being the most robust for Rhyncho, both preventative & curative The SDHI actives are more long lasting than other chemistry groups, providing enhanced disease control and extending the protection period by up to 3 weeks. They also give consistent increases in green leaf area in the field, delay senescence and improve drought tolerance, all components that build yield.

Bixafen, available in mixture with prothioconazole as SILTRA for barley is particularly strong on Rhyncho. Xemium is also very strong but its partner triazole in ADEXAR, epoxiconazole is not as strong as the Bayer triazole. BASF also have boscalid, another SDHI active available in mixture with epoxiconazole as CHORD. Whilst the boscalid is not as curative as xemium, CHORD is very strong on Rhyncho and also has excellent activity on Ramularia at T2. Isopyrazam (Syngenta), in mixture with cyprodinil as BONTIMA for barley is particularly strong on rusts. None are particularly strong on Mildew or Fusarium.

Chlorothalonil is still an option when used preventatively to improve Ramularia activity but only when an SDHI is not being used at T2. (It has no activity on any other barley diseases.) FIELDER is an ideal triazole partner, combining both TALIUS and chlorothalonil in the one pack to control both  Ramularia and Mildew Where the SDHI chemistry is not being used, strobs also have a very important role in the T2 fungicide programme in those crops with good potential, improving control of Brown Rust, Net Blotch & Rhyncho. With a different mode of activity to the triazoles, it is an excellent partner in resistance management.

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. Mildew is also present in all varieties depending on whether TALIUS has already been applied.

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.

Epoxiconazole and prothioconazole remain the key triazoles for controlling Septoria. However the difficulty in controlling this disease should not be underestimated. Part of any pathogen’s survival mechanism is to change in response to outside influences that adversely affect its development, and the Septoria pathogen is continuously modifying itself in response to a fungicides’ mode of action, developing ways around it. Population strains of the Septoria pathogen continue to change. New genetic variants are more able to tolerate particular fungicides, becoming harder to kill with epoxi and prothio (Group 1 triazoles). However these same strains are easily controlled with certain older triazoles including tebuconazole and metconazole (Group 2 triazoles). Hence the rationale for the best performing triazole products in recent years to be co-form triazole mixtures. In PROSARO, Bayer have demonstrated over the last 3 years that the effect of two triazoles mixed together is greater than the sum of both when used separately, the tebuconazole improving the product performance on Septoria over straight prothioconazole. BASF have identified a similar effect with BRUTUS, a mixture of epoxiconazole and metconazole. This product consistently outperforms straight OPUS, gram for gram and produces results in the field similar to PROSARO.

 

Spring Barley Weed Control – Potato Weed Control

The rising temperatures over the last week have been very welcome for all crops but unfortunately awns have begun to appear on winter barley with critical plant growth regulator missed. Mildew is present on almost all winter cereal crops and should be treated at T2 timing. In spring barley & spring wheat an early application of ADJUST increases root development and the numbers of surviving tillers which will improve crop establishment and yield. Because of the spring crops more rapid progression through the growth stages than the winter crop, the growth regulator must be applied very early to maximise the suppression of apical dominance and therefore divert nutrients and growth to promote secondary tiller development. Optimum timing for barley is from the 2nd expanded leaf stage to beginning of tillering, GS12 – 21 whilst in wheat the optimum timing is slightly later, 5 leaf to mid tillering, GS15-24. This treatment also gives a consistent straw shortening effect in wheat, but not in barley.
Leatherjacket numbers are considerably higher this year with widespread damage to grass swards particularly in the west of the Province. Damage is now becoming evident in some of the earlier drilled cereals. Feeding activity and therefore the likelihood of damage will increase as soils continue to warm. Crops most at risk are those drilled into old ley or dirty stubble, but monitor all emerging crops closely for signs of damage. The grubs will be quite easy to find in areas of poor emergence, when the soil is dug down to a depth of 4-5cm.

Spring Barley

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. 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. However they 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 and fat-hen). Ideal partners are Compitox,Oxytril Cm and Spitfire. Each of these partner options are very tank mixable, and other products such as ADJUST and MAXMAN can also be safely added.
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-ureas products will improve control. Spring barley, spring wheat and spring oats undersown with grass and clover should be treated with TRIAD and where clover is not important MIRCAM PLUS should be applied. 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

All winter barley crops have now received their T1 fungicide, with the T2 planned for the coming weeks. Prothioconazole in (MOBIUS or SILTRA) or epoxiconazole in (MANTRA or ADEXAR) at this critical timing will give maximum benefit over straight triazole products. Mildew levels are extremely high and thereforeTALIUS should be added.

Winter Wheat

Like the winter barley, the mild winter means Septoria and Mildew levels are higher than seen at the same time in recent years. Yellow Rust has also been found in some earlier sown crops and the threat will remain high. Robigus and Einstein have both broken down to new races of this disease and are more susceptible than ever. Like the barley, the T2 application should now be planned as recently applied fertiliser coupled with warmer temperatures will push crops through the growth stages very quickly.

Potatoes

With planting progressing well to date, this year’s crop is going in in almost perfect conditions right across the Province. Drills are moist and with this week’s increased temperatures rapid emergence of both crop and weeds will occur. Therefore growers should be planning weed control now, taking good advantage from the moist soil conditions. Most weed control programmes are based on residual products ie 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. Contact products such as RETRO,ROUNDUP and TITUS may be applied. All require the inclusion of a residual partner to maintain clean drills up to the time of the crop canopy closing the drills. Residual products are DEFY, SENCOREX, AFALON and GAMIT.
All potato herbicides carry timing restrictions and some namely SENCOREX have varietal restrictions and it is therefore important to seek advice on the best product choice.
SHOGUN has a full recommendation for scutch control on ware potatoes. It will also give excellent control of perennial ryegrass, wild oats and volunteer cereals. If the crop is under drought or temperature stress when sprayed, transient yellowing may occur. For this reason its use is not approved on seed crops since these symptoms could be confused with viral disease.
Grass and weeds have been under stress up to now and where silage is still some weeks away there is an opportunity to apply herbicide.

 

Basf Adexar Launched

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Grassland Weed Control – Cereal Fungicides

This has certainly been a very changeable week with wintery showers and night frosts. Many crops are under stress and care should be taken not to rush out and spray these where timing is not crucial. 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 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.

SPITFIRE is now in its second season, it contains two active ingredients, a high loading of the sulfonyl-urea (SU) florasulam, and fluroxypyr. It has a very wide spectrum of weeds controlled 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 these antagonisms, a minimum time interval must elapse between application of the BLW herbicide application and this application.

Disease Control

The new fungicides containing an SDHI (Succinate Dehydrogenase Inhibitors) component add very cost effective yield benefits to both wheat and barley. Bixafen (Bayer), boscalid (BASF) and isopyrazam (Syngenta) are longer lasting than other chemistry groups, providing enhanced disease control and extending the duration of protection by up to 2 weeks compared to triazoles. This season sees the launch of another new SDHI molecule from BASF, xemium. In contrast to the other SDHI’s xemium appears to exhibit very good curative as well as preventative activity. Because this chemistry is considered to be at high risk to fungicide resistance, so they must only be used in mixtures with triazoles.
All of the SDHI’s give excellent activity on Rusts and Net Blotch. Bixafen, available in mixture with prothioconazole as AVIATOR for wheat and SILTRA for barley is particularly strong on Septoria and Rhyncho. Boscalid is available in mixture with epoxiconazole as CHORD and approved for both wheat and barley. As well as being very strong on Septoria and Rhyncho, it is the strongest molecule on Eyespot and therefore most suited to T1. It is also very strong on Ramularia in barley at T2. Isopyrazam, in mixture with cyprodinil as BONTIMA for barley and with epoxiconazole as SEGURIS for wheat is particularly strong on rusts. None are particularly strong on Mildew or Fusarium.
Xemium will be available in co-formulation with epoxiconazole, marketed as ADEXAR. As well as being one of the strongest performers against Septoria, because of its curative activity it is also the strongest product when timings have been stretched and therefore kickback is required.

Potatoes

Maincrop potatoes are currently being planted into ideal soil conditions right across the province. There are two types of herbicidal activity;
Contact herbicides which are those that must come into direct contact with the leaf of the target weed and will control all weeds that are emerged at the time of application – known as post emergent activity (post-em) and residual herbicides which move into the soil and prevent germination of the target weed before it emerges – known as pre-em
have only the one mode of activity; i.e. a contact will have no effect on weeds not yet emerged, while most residuals will not control weeds already emerged. In addition the residuals need sufficient soil moisture to work properly and in dry conditions residuals will not perform well.
Shogun has a full recommendation for scutch control on ware potatoes. It will also give excellent control of perennial ryegrass, wild oats and volunteer cereals. If the crop is under drought or temperature stress when sprayed, transient yellowing may occur. For this reason its use is not approved on seed crops since these symptoms could be confused with viral disease.

Grassland

Weed infestations can impact significantly on the yield and quality of grass for both grazing and cutting with trial work performed over the last two years by Dow Agroscience producing some shocking statistics. To put into perspective some of the figures, control of docks can give an average yield increase of 2.66t of DM/HA, enough grass for a cow to produce 5470 litres of milk. At 28p a litre this converts to £1531.00.Farmers will almost always apply fertilizer to grass swards because they can see the benefits but if I was to tell you that 3 bags of CAN could produce 320kg grass DM/HA which could produce 706 litres of milk at a value of £197.00 compared to dock control producing over 2000kg grass DM/HA which could produce 4452 litres of milk at a value of £1246.00.Which gives the better return?
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 reinfestation 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.
The ideal time to spray docks is when they are in full leaf at the rosette stage just before the flowering stalk appears. For effective root kill it is necessary to use translocated herbicides such as dicamba, fluroxypyr and triclopyr to allow sufficient time for them to move from the leaves down into the root system. This is usually 3-4 weeks. Examples of products, which contain dicamba, are Grassland herbicide, Foundation ,Mircam Plus and Dockmaster. Doxstar and Pastor contain both Fluroxypyr and triclopyr and are preferred on silage ground as they have little or no effect on the growth of grass.Triclopyr has a much wider weed spectrum and greater translocation than straight fluroxypyr and therefore there is greater efficacy and longevity achieved by mixing these two actives especially on docks. Forefront may be applied onto grazing ground giving excellent weed control with no effect on the grass. Forefront contains Fluroxypyr and aminopyralid. As well as controlling docks it will control chickweed, buttercup, dandelion, nettle and thistle.
Spot control of Nettles, Thistles and Docks can be achieved using Grazon 90 or Nushot.

 

Bayer Aviator Xpro Launched

Click Here to read more…

 

Weed Control In Winter Cereals – Leatherjackets – Growth Regulator

The excellent weather conditions experienced over last weekend and into this week have allowed Land to dry out well and spring fieldwork is progressing well. Growth has been good this week and crops have greened up well where fertilizer has been applied. 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. Potato planting has begun in some parts of the province and early carrots have also been sown. Many grassland farmers were keen to spray swards for chickweed and docks but it is too soon yet as night frosts have been occurring and weeds have become hardy hence will not take in the chemical particularly well.

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. SPITFIRE is a new herbicide from Dow containing two active ingredients, a high loading of the sulfonyl-urea (SU) florasulam, and fluroxypyr. It has a very wide spectrum of weeds controlled 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 these antagonisms, a minimum time interval must elapse between application of the BLW herbicide application and this application. ALLY MAX and SPITFIRE should be applied onto any winter barley crops not yet sprayed but this will not control any grass present.

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.

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.

This season sees the launch of the new BASF fungicide ADEXAR which is a mixture of xemium technology and epoxiconazole. ADEXAR is very curative and has acropetal mobility within the leaf area. It is labeled for both wheat and barley. This joins a number of newly approved cereal fungicides containing a new family of chemistry known as SDHI’s.

Preparing For Spring Crops

The focus over the last couple of weeks has been on preparing ground 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 increase in 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 2011.Pre ploughing treatments with Dursban or Cyren are more effective than those applied once any damage is under way in the spring-sown crop.

It is essential to soil test prior to planting any crop, whilst it may seem expensive it is money well spent.

Winter Barley & Winter Wheat Growth Regulation

There are two types of lodging; stem-base lodging and brackling. 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. Brackling is where the stem folds over part way up the plant, and occurs as a result of an inherent weakness of the variety, very dense canopies, and bursts of rapid growth.

Whilst CHLORMEQUAT (3C) will reduce the likelihood of brackling, it will have no effect on root growth; ADJUST on the other hand is active on both types of lodging when applied at the correct timing.

An application of the growth regulator often goes on with a T1 fungicide application sometime around 1st-2nd node, GS31-32. At this timing it primarily stiffens the stem by shortening the internodes, so reducing the likelihood of brackling. However when applied before the end of tillering, GS29, the growth regulator increases root growth also and so reduces stem-base lodging.

ADJUST will work right down to 1°C and is safe to the crop, particularly when applied in tank-mix with other pesticides. When applied early it also has a very significant effect on increasing tiller survival so improving yield potential. It is an excellent aid to managing more backward crops when applied at mid-tillering, GS22-24, helping these crops thicken out.

 
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