Crop Crack

Time For Weed Control In Grassland

The last couple of weeks have offered some opportunity for farmers to get up to date with much needed fieldwork. As the season is racing on jobs are being done in less than ideal conditions. 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 wet winter, so weed numbers are much higher than usual. As many of our traditional herbicides have disappeared in recent years the good news is, this season we have now in our possession some very effective new armoury.

DOCKS

As thoughts turn to silage, 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. FOREFRONT T may only be applied to grazing ground. However PASTUREPACK launched this season by Nufarm will cover a similar range of weeds and may be applied on silage ground. 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 establishes grass.

CHICKWEED

There are 2 types of chickweed, common chickweed which has a smooth leaf and is the most commonly found, 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.LEYSTAR will be used widely on new sown leys this season where clover is not important. As well as controlling both strains of chickweed it will give very good control of dock and thistle.

DOXSTAR applied at 1lt/ha, will control both types of chickweed in established swards. Neither will check the growth of immature grass plants and are not clover safe. 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 when used correctly. As well as controlling a wide range of BLW’s TRIAD gives excellent control on chickweed. It will also control seedling docks (not those regrowing from roots), but has no effect on thistles or buttercup. Add SPRUCE to bring in control of these weeds.

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.

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.

WINTER CEREALS

The increases in temperatures over the last couple of weeks have made a marked impression on winter crops as they start to grow. Yellowing and patchy areas are becoming evident across fields as a result of localised variations in soil conditions varying the availability of N, P and K to the crop; wetter spots and compaction on headlands in particular are now showing up. Depending on when and if a T0 treatment was applied, diseases are prevalent in all fields. All have completed tillering, with the most forward approaching GS 33. Weed control should now be complete on both winter barley and winter wheat.

 

Barley Heads Towards Harvest!

Winter barley crops are looking really well and the gates are now closed until desiccation pre-harvest. Most winter wheat crops have received their T3 earwash with a few later drilled crops still to be sprayed.The cornerstone for the T3 head spray fungicide remains the double dose triazole mixes, despite their decline in Septoria efficacy. Tebuconazole is the most effective triazole for Fusarium in particular and an important active in its own right at this time. The addition of a strobilurin is essential to maximise the persistence of the triazole, strengthen activity on Yellow Rust, and delay early leaf senescence. Good grain fill is totally dependent on retaining green leaf area for as long as possible, and the addition of the strobilurin extends the retention of green leaf tissue. ADHB trials continue to show pyraclostrobin (COMET) to be the highest rated strob for use in wheat, being the strongest performer on Yellow rust and the late ear diseases.

Aphids in cereals

As the grains begin to fill the aphids begin to feed at its base on the ear, drawing off the sugars that should be filling the grain if left unchecked. Growers need to continue checking crops for aphids right up to early milky ripe stage (GS73) in barley, late milky ripe (GS77) in wheat, and spray if present in numbers. Where aphids are not present, unnecessary application should be avoided as any insecticide application at this time is not bee friendly. Of the aphicides approved for use for this purpose, SUMI-ALPHA is the least harmful to bees.

Pre Harvest Glyphosate

Winter barley crops are ripening well and thoughts will now turn to grain quality, moisture levels, and ease of harvesting. This year in particular grasses and other weeds are a real problem in many fields. Pre harvest application of glyphosate is an essential tool to improve the efficiency of harvesting, giving a range of benefits:

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Harvest Management

-all green tissue removed – ripens any green stems, leaves and pickles so allowing cutting to start earlier in the day & continue for longer

-no green pickles reducing overall grain moisture and drying costs

-less grain lost over straw walkers caused by green material during threshing

-faster straw clearance reduces length of weather window required

-limits sprouting in laid crops

Scutch & general weed control

-the most effective time to control scutch in tillage ground

-desiccates any other green grass & broad-leaved weeds present, facilitating lower grain moisture, faster harvesting and sooner baling of straw.

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Note however, do not use glyphosate on any crops where seed may be saved for re-sowing.

Independent trials carried out over a number of years in GB looking at the effect of using Roundup in various replicated treatments consistently show moisture contents being reduced by 2.0-2.5% at harvest compared to plots where no treatment is applied.

With a wide range of glyphosate products available, which offers the best performance in the field, and best value for money? First off, it is not the price per drum that should be compared. With different formulation types having different strengths and therefore different rates of use, it is the price per acre treated that should be compared, and what level of performance is being obtained from each. Glyphosate itself is not very soluble therefore it depends very much on the salts and wetter’s to enhance its performance. The potassium salt in Roundup Energy is taken up significantly faster than isopropylamine salt; as a result Roundup Energy is rainfast within 1 hour of application and cultivation can commence as soon as 2 days after application whereas the IPA glyphosate products need a minimum of 6 hours to be rainfast and 5 days minimum before cultivating.

Application should be made once the grain moisture gets down to 30% or below, ideally 10-14 days (and not less than 7 days) before cutting. An easy and reliable test to estimate this 30% moisture level is to press the thumbnail into a number of grains; if the indentation holds on all the grains the crop is ready for spraying.

Potatoes

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 that have zoospore activity are the most effective 1st 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. 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 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.

 

Disease Control Crucial Now On Spring Crops

Spring Barley

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In our typically moist climate Rhyncho and Net blotch infections are breaking out along with high incidence of mildew. Even where crops are considered to be clean, controlling Rhyncho early is much more effective than leaving it until it is seen. Once this disease comes into the crop, any eradicant treatment has limited efficacy, will stress the crop and increase the risk of Ramularia infection. The T1 application should be applied at the end of tillering to the start of stem extension, GS24-31. The T2 is then applied 3-4weeks later during late flag leaf emergence to booting, GS38-49.

Product options continue to be based around core triazoles such as prothio, epoxi and cyproconazole. Prothioconazole remains the strongest performing triazole but epoxiconazole mixes are equally effective options, ensuring the various strains of disease are exposed to as many different actives throughout the programme as possible. Strobilurins continue to improve the performance of the triazole partner, improving Rhyncho, Net Blotch and Rust activity. MOBIUS is a mix of prothioconazole and strobilurin, and is one of the strongest barley products available. SDHIs will also give very good disease control at T1 but if they are only going to be used once then the T2 timing is the better fit for them as it is the most responsive timing in spring barley. Chlorothalonil is also an important component, enhancing the control of Ramularia when applied onto the flag leaf and ear.

 

All trial work continues to underline the responsiveness and therefore improvement in yield and margins of spring barley to a correctly timed 2-spray fungicide programme, consistently outperforming a single application programme. The ‘single hit’ approach attempts to provide protection for the 8-10 weeks required, an unlikely task in almost any scenario.

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Where however a low input approach is been adopted, the one application will give best response when applied during mid stem extension GS32-33, maximising Rhyncho control on the upper leaves. This is normally some weeks after the optimum timing for the herbicide application. Mid stem extension is too soon however to get reliable Ramularia control and unlikely to prevent a late infection of Rhyncho.

Spring Wheat

The young spring wheat plant isn’t subjected to the same disease burden as the overwintered winter wheat plant, therefore a two-spray programme usually suffices, with the T1 applied at 1st-2nd node, GS31-32, and the T2 applied at some point during booting, GS41-49. Whilst a large proportion of these crops are harvested as whole-crop earlier than the conventional combined crop, the feed quality of the harvested crop is very dependant on maximising grain-fill, therefore product choices and rates are similar to those of the winter crop, with significant yield responses to a proper programme.

 

Spring Oats

Powdery Mildew and Crown Rust are the most damaging diseases in this crop. CAPALO & COMET in mixture is the strongest performer in terms of controlling both these diseases and therefore yield improvement. Metrafenone (an active in CAPALO) is extremely effective in terms of Powdery Mildew control. The addition of COMET (a strobilurin) gives unrivalled Crown Rust control.

CAPALO and COMET should be applied at 1st – 2nd node, (GS31-32) eradicating any Mildew and Rust already present, and providing persistency right through to harvest.

Lodging Control

Application of SELON at early tillering on spring barley 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 (as has happened this season because of late planting, high temperatures and soil moisture at present) 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 can be used but its cut-off in spring barley is 2nd node, GS32. CANOPY is a very useful alternative, safe to the crop and able to be used right up to and including full flag leaf, GS39. If this timing has past, CERONE can be applied up to before awns visible, GS45.

 

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. If the crop still looks very rank and at risk of lodging as the stem elongates, apply CERONE only, as the flag leaf is emerging. The correct timing for treating spring oats is at 2nd node, GS32.

 
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