Poor spring conditions have hampered growth

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The last fortnight has offered very little spray opportunity but every available chance must be taken to ensure correct spray timings.

Most winter barley crops are now at flagleaf fully out to awns just visible. Because of the very poor growing conditions this spring, nodes and crop height is not a good indicator alone of the plant growth stage. Growth stages in cereals are hugely influenced by day length. The longer days are driving ear development, and with it ear emergence.

In winter wheat the weakest part of the stem tends to be the lowest internodes and therefore growth regulation at this time maximises strengthening, in barley it is the higher internodes that are weakest.

In winter barley the SELON growth regulator applied some weeks ago enhances root anchorage and tiller survival, but has little effect on controlling stem lodging. It is during the later stem extension stages and early flag leaf emergence that the maximum straw strengthening effect will be achieved. When the application is delayed beyond this timing efficacy drops off rapidly, as with each passing day the stem has already added on further length.

In any event it is essential the growth regulator is applied before the awns start to appear - a late application as the awns are emerging can damage the emerging ear. The T2 fungicide program should now be planned for winter barley. Properly protecting the top three leaves and ear at T2 is critical to yield and profit - up to 80% of the yield is generated from these leaves.

Foliar disease not controlled effectively at this time will hasten the senescence of these leaves during grain filling, and therefore compromise yield and grain quality. Yet there is little point in applying any input if it does not give a financial return. To get the best return on fungicides, applying them at the correct timing is critical.

Spring Cereals

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 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 certain herbicides in NI is not a new problem – continuous use of straight metsulfuron (ALLY) in previous years has resulted in strains of chickweed that are no longer controlled by this chemistry. 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. ALS resistance is becoming a bigger problem with other weeds now developing this type of resistance, including mayweed and poppy. This development seems inevitable following the continued use of products with the same single mode of action, and more than ever mixtures of products with different modes of activity are essential to maintain good weed control.

ALS inhibiting herbicides must therefore always be tank-mixed with another non ALS herbicide to ensure satisfactory weed control, especially of chickweed in NI.

Leatherjackets

Leatherjacket numbers are very high this year with widespread damage seen in recent weeks to new leys and established grass swards particularly in the west of the province. Damage will become evident as spring crops emerge, leaves and whole plants yellowing, cut off just below ground level.

Crow activity is also a sure sign of leatherjackets being active. Crops most at risk are those drilled into old ley or dirty stubble, but monitor all emerging crops closely for signs damage. Feeding activity and therefore the likelihood of damage will increase as soils warm up as the leatherjacket continues to feed for some weeks yet before hatching out in late May/early June.

Growth manipulation

Since tillers are a critical component of yield and tiller numbers decline the later the crop is drilled, it is important that these crops be encouraged to tiller to improve yield potential. Because of the more rapid progression through the growth stages than the winter crop, the growth regulator must be applied very early to maximise the suppression of the main stem development (apical dominance) and therefore divert nutrients and growth to promote tiller development. Optimum timing for barley is from the two expanded leaf stage to beginning of tillering, GS12–21; in wheat the optimum timing is slightly later, five leaf to mid tillering, GS15-24. SELON is the only chlormequat product approved for use on spring barley. Because an early application suppresses the main stem development and so diverts the growing efforts to the tillers, this extra growing effort also increases root development in the plant, improving crop establishment, stem base lodging (not brackling) and yield. This treatment also gives a consistent straw shortening effect in wheat, but not in barley.

Horticulture

The recent frost has had serious implications on many of our horticultural crops especially the apple and early potato crop

SEAMAXX is a seaweed based fertiliser that can help improve resistance to environmental stress such as extreme temperature, wind damage and drought.

It helps the orchard to maintain growth during hostile growing conditions, by reducing stress there is more energy available for flowering and fruit set leading to improved yields. At this critical time MACCANI should be applied as it is safe through the blossom.