Crop Crack

Weed Control Essential For Quality Silage

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. 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 Ultra may be applied in established 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. Both Envy and 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.

 

 

 

 

 

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.

 

 

Ground Conditions Make Drilling Difficult

Drilling

The conditions a couple of weeks ago allowed some winter drilling to commence. Unfortunately the turn in the weather has been stop start with herbicide application made very difficult. The only time to control grass weeds in winter barley is the autumn and so it is important to avail of any spray opportunity. Early drilling of winter wheat dramatically increases the risk of take-all following continuous cereals. Therefore a seed treatment is advisable. BYDV is a disease carried by aphids and passed into the crop when they feed on the young plants as they emerge through the ground. Once infected the disease cannot be controlled. Grassy stubbles and volunteer cereal plants act as host plants for aphids. The earlier the crop is drilled, the greater is the risk of infection as the seedling plants are emerging at a time when aphid numbers are high and actively feeding. As the seed treatment REDIGO DETER is no longer available an application of Sumi-Alpha should be applied from the two leaf stage of the crop. Product persistency is very dependent on temperature, increasing as temperatures fall. Applications made whilst temperature remain mild are broken down in 2-3 weeks and therefore most crops will require further applications until aphid feeding ceases as a result of cooler weather.

Slugs

Slugs have thrived throughout the damp summer and damage has already been seen in some oilseed rape crops. All autumn drilled fields should be monitored closely for damage. Loose unconsolidated seedbeds are more prone to damage as slugs can move more easily as moisture conditions dictate. IROXX ferric phosphate slug pellets which have no water issues may be applied at the first sign of damage.

Autumn Herbicides

The key to good herbicide control is early timing, before or soon after emergence of the crop. Residual herbicide product persistency depends very much on damp soils and cooler temperatures. Annual meadow grass is the main target weed in NI as this weed is the most damaging in all cereal crops. Flufenacet is the principle active in autumn herbicide programmes to control AMG giving pre and post-em activity on grass weeds. Flufenacet is available in mixtures such as CRYSTAL and NUCLEUS. Nucleus which was launched in 2018, is a combination of flufenacet and diflufenican, providing broad spectrum weed control in a very cost effective package.  Complete control of autumn emerging weeds including annual meadow grass can be achieved for as little as £13.00 /acre.    Crystal which contains pendimethalin and flufenacetgives improved control of brome species in wheat and barley but groundsel in particular will still need to be treated in the spring.

 

 

Rain Driving Growth in Spring Cereals


The mix of sunshine and rain over the last couple of weeks has provided a period of good growth in all crops, but with this comes a ramping up of weed and disease activity. The heavy showers in recent days have encouraged even germination of weed populations in all spring cereal crops, and if not already sprayed for these, should be done so as a priority in coming days, as performance will fall off rapidly when the weeds become larger and the crop canopy closes, shading out the weeds underneath. As a result of a near ideal balance of heat and rain since planting, all spring crops are now well established and well into the tillering growth stage. Most are clean and canopy cover is consistent right across fields.

Chlorothalonil revocation update

Following the announcement of its revocation earlier in the year, the use up period for chlorothalonil containing products has been announced. Products may be sold up to 20th November this year, and growers will have to the 20th May 2020 to use or dispose of stock. Whilst the fact growers will have the active for much of next season is better news than might have been expected, longer term its loss will impact significantly on crop protection programmes in terms of efficacy and resistance management.

Disease Control

Spring Barley

At the moment crops look pretty clean, so in most cases the lower end of the dose range will suffice, but with disease risk closely linked to heat and moisture, decisions on rates are the ultimate in-field decision and should be tailored to the disease pressure in each field.

Even where crops are considered to be clean, controlling Rhyncho early is much more effective than leaving it until it is seen. Once infection has come in, any eradicant treatment has limited efficacy, and the infection will stress the crop, increasing 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 timing should be aimed to continue control of Rhyncho and Net Blotch, but also timed to maximise control of Ramularia. Flowering and senescence are major triggers of symptoms, but other stresses also play a part including bursts of sunshine, diurnal temperature fluctuations, and the presence of other foliar diseases. This spray needs to be on ahead of Ramularia symptoms appearing on final leaves one and two and persist for long enough to keep the crop green well in to grain fill. The best compromise timing for this is booting to very early ear emergence, GS41-49.

Options for T1 are 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 improve the performance of the triazole partner, improving Rhyncho, Net Blotch and Rust activity. SDHIs will also give very good broad spectrum disease control, but factoring in cost effectiveness, are a better fit at the more responsive T2 timing.

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, GS31-31, 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. OPUS TEAM & COMET in mixture is the strongest combination in terms of controlling both these diseases and therefore yield improvement. Fenpropimorph (an active in OPUS TEAM) is extremely effective in terms of Powdery Mildew control, and the addition of COMET (a strobilurin) gives unrivalled Crown Rust control.

A single application of fungicide 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

Spring Barley

Application of SELON at early tillering will have increased tiller and ear numbers and therefore yield potential, but will not have given any reliable strengthening of the straw. Stems that extend rapidly during the stem elongation phase (as is likely to happen 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.

Spring Wheat

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 or CANOPY, as the flag leaf is emerging.

Spring Oats

The optimum timing for treating spring oats is with SELON at 2nd node, GS32. However if the oats remain at risk of lodging, a follow up treatment of CANOPY can be applied during flag leaf emergence

 
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