Most crops continue to benefit from the recent hot weather with many racing through the early stem elongation stages in a matter of days. However the late planting in May and dry weeks since make a challenging combination. With temperatures well above average and daylight hours considerably longer than for a crop drilled in early April, such conditions increase the likelihood of crop stress through too much or too little moisture, or not enough nutrient availability to support the potential rate of growth. 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 Mn 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 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.
Dry conditions have held back disease and at present all crops are clean, but in our typically moist climate the likelihood of Rhyncho and Net blotch infections breaking out are inevitable unless controlled in good time.
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.
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.
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.
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.
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 has happened this season because of late planting and high temperatures ) 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.