Crop Crack

Time For Weed Control In Spring Cereals

The extended period of dry weather has allowed farmers to make significant progress on field work. For many growers it has been the earliest end to a spring planting season in a number of years.

Weed control has been difficult to date as crops are growing well but weeds are only just germinating due to the very dry conditions. To minimise the effects of competition on the crop and optimise the level of weed control, herbicide application should be carried out once all 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 when they are at the 2-4 leaf stage is much more effective especially on difficult weeds such as fumitory and knotgrass. Whilst chickweed resistant to a wide range of herbicides is commonplace right across the province, the  inclusion of the active arylex into the herbicide tank-mix programmes in recent years has given improved control of  chickweed and other problem weeds including fumitory and sets a new benchmark in terms of weed control in spring barley and wheat. It belongs to a chemical family classified as synthetic auxins, similar to the old hormone chemistry and controls a wide range of broad-leaved weeds including those resistant to the ALS herbicides in most winter and spring cereals, including robust control of fumitory, fat-hen and ALS resistant chickweed. Marketed as ZYPAR, it is available in co-formulation with the active ingredient florasulam and has excellent multiway compatibility along with a very wide range of other pesticides and has no major following crop restrictions. It gives excellent control of a wide range of broad-leaved weeds that includes chickweed, fumitory, fat-hen, groundsel, brassica weeds, and cleavers, but its weakest weed is redshank. Whilst it will control it alone up to 6-leaf, when tank-mixed with ALLY MAX or FOUNDATION it will control redshank right up to flowering.

Temporary nutrient issues

Manganese (Mn) deficiency is widespread in much of our local soil types, and particularly damaging to leaf vigour and yield if not treated. Continuous cereal cropping, ground recently limed and dry soils all increase the likelihood of deficiency.  Symptoms begin with small pale green speckles appearing throughout the leaf and these will progress to turn brown unless treated. Barley is particularly susceptible to Mn deficiency. MAXMAN is a highly concentrated Mn(40%) in a completely soluble chelated nitrate formulation and also supplies 10.8% Nitrogen and 11.4% Sulphur

 

A young plant that is growing extremely rapidly is producing a huge amount of new plant tissue each day. This rapid growth is limited only by the availability of nutrients to synthesise biomass, dependant on soil fertility and the plant’s own root development to take up the nutrients. It is at this time therefore when nutrient deficiencies are most likely to appear and in doing so, suppress growth rates.

The application of a broad-spectrum trace-element mix along with key macronutrients during this time is a very useful and beneficial way to supplement the plant’s nutrient requirements during periods when availability does not meet demand, most likely to coincide with phases of rapid growth ie. during tillering and as stem extension begins. Application of a balanced and readily available source of macro & micronutrients that is topping up what is being made available from the  soil at this key time will minimise the adverse effects of restricting nutrient availability. CEREAL HIGH N-supplies 250gm N, 125gm S, 38gm Mg, 93gm Mn, 45gm Cu and 15gm Zn per ha

 

 

FASTMIX MAGNESIUM PLUS is an alternative product specifically formulated to meet the increased micronutrient demand of cereals and other combinable crops with good yield potential. It is a quick acting foliar fertiliser containing high levels of magnesium and sulphur as well as manganese, zinc and boron, all in a water soluble form and readily available to the plant. It is very compatible in tank-mix with most pesticides and can be applied along with the T1 and T2 fungicide applications. Being a dry formulation, it should be fully dissolved in the tank first and other products added afterwards.

 

 

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.

 

 
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