Crop Crack

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

 

Spring Crops Make Good Start

Spring Cereals

The much more pleasant milder night-time temperatures have seen a welcome burst of new growth in all crops. All spring crops have now brairded and without the more usual effects of waterlogging seen in other years, are looking very well. Although weeds are also emerging fast as a result of last weeks rain, be sure all are well through before spraying. Watch too the size of the annual meadow grass if this weed is also to be controlled – efficacy falls off rapidly once it begins to tiller.

A well timed application of SELON will encourage tiller numbers and tiller survival. This treatment must be well timed to maximise its effect, optimum timing for barley is from the 2 expanded leaf stage to beginning of tillering, GS12–21; in wheat the optimum timing is slightly later, 5 leaf to mid tillering, GS15-24. Many crops will have now passed through these growth stages. It is important to note that this season aphid numbers are the highest I have seen for a very long time and it would be advisable to apply an aphicide to control the spread of BYDV.

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, rather than delaying to coincide with the 1st fungicide application.

Broad leaved weeds resistant to particular groups of herbicides in NI is not a new problem – chickweed resistant to herbicides such as ALLY has been widespread throughout the province for some years. Sulfonyl urea (SU) herbicides such as metsulfuron have a single mode of activity, blocking the production in many BLW of a key enzyme, acetolactate synthase. Products that use this mode of activity are known as ALS inhibiting herbicides and include the SU chemistry. As well as chickweed, mayweed and poppy have also developed widespread ALS resistance. This particular resistance problem has been managed by including herbicides into the tank-mix with different modes of activity to maintain good weed control.

 

In NI spring cereals ZYPAR will give excellent control of a wide range of weeds that includes chickweed, fumitory, fat-hen, groundsel, brassica weeds, and cleavers. Its one relative weakness is redshank. Whilst it will control it to 6-leaf, it should be tank-mixed with another herbicide to ensure redshank right up to flowering is satisfactorily controlled. ALLY MAX and FOUNDATION are excellent tank-mix partners for this purpose.

 

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.

 

Winter Cereals

Winter cereals have greened up well and are now racing through the growth stages. Awns are now out on all winter barley crops with both T2 application and growth regulator applications complete. Winter wheat crops which have not yet received T2 should be treated as soon as possible along with the growth regulator if required.

 
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