News

The catchy weather in April and early May has meant Septoria pressure has been extremely high especially on those earlier drilled winter wheat crops. The ear has now emerged on many crops of Extase and mildew is present on the more forward lush crops of Graham. Aphid numbers are currently very high in both winter and spring cereals. Any late drilled spring barley should be inspected and if colonies are found on over 50% of plants it should be treated to reduce the risk of BYDV.

Most spring cereal crops continue to benefit from the recent improved temperatures with many now racing through the growth stages.

Crop Nutrition

As soils warm up and daylight hours are considerably longer the likelihood of crop stress through too little moisture, or not enough nutrient availability to support the potential rate of growth is now showing up in later drilled crops. As a result, many fields are beginning to show variation of colour and growth, and such variation is very difficult to address in a satisfactory way. Manganese (Mn) deficiency is widespread in much of our local soil types, and particularly damaging 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 manganese deficiency.

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. 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, 38gm Mg, 45gm Cu and 15gm Zn per hectare.

Fungicide Timing

The T1 application should be applied from late tillering to the start of stem extension, GS24-31. Since this treatment is primarily for insurance and the risk of infection being present at this time is low, it follows that rates can be reduced compared to the winter crop. The T2 is the more responsive timing in spring barley when Ramularia is also a significant risk, therefore more of the spend should be directed at the T2 timing. This application should be applied from first awns visible to ear completely emerged, GS49-59. Also bear in mind too that preventing Rhyncho infection is much more effective than trying to control it curatively. Once infection has come in, any eradicant treatment has limited efficacy, and the infection will stress the crop, increasing the risk of Ramularia infection sooner rather than later.

Lodging Control

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 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/CRATUS can be used but its cut-off in spring barley is 2^nd 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.

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.

Spring Cereals

Spring crops are looking very well and without the more usual effects of waterlogging seen in other years.  Although weeds are emerging fast as a result of last week’s rain, be sure all are well through before spraying. Also watch the size of the annual meadow grass if this weed is also to be controlled – efficacy falls off rapidly once it begins to tiller. 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 1^st 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. Sulfonylurea (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 spring cereals, ZYPAR will give excellent control of a wide range of weeds that will not be controlled by Ally on its own. These include chickweed, fumitory, fat-hen, groundsel, brassica weeds, and cleavers. It’s 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 SAXON are excellent tank-mix partners for this purpose.

Winter Cereals

Winter cereals have greened up well and are now racing through the growth stages. Awns are now out on almost all winter barley crops with growth regulator applications complete. The cool nights during April held back the crop response to nitrogen, but this has turned around and all nitrogen applications should be completed in the coming days to maximise green leaf development and crop yield.

Winter wheat crops which have not yet received T2 should be treated as soon as possible along with the growth regulator if required. The cool dry April and well timed T1 treatments have kept Septoria infection low, but it is present in all crops and remains a key focus for T2 treatments planning forward. Yellow Rust has been observed at low levels but perhaps a combination of cold nights and effective varietal resistance has meant that there have been no explosions of infection we were more familiar with other years.