The pleasant conditions over the last couple of weeks have allowed much needed fieldwork to get underway. Most winter cereal crops have now received their first nitrogen application. It is now time to assess what weeds are present and a fungicide treatment should also be planned. Broad-spectrum weed control should now be carried out in winter cereals as temperatures improve. Fields where wild oats are expected to be a problem should be identified and sprayed once it is certain all the wild oats have germinated and are through the ground.

Winter Barley

The majority of crops are at varying growth stages ranging from GS25-GS31.

It is essential to check crops as many weeds are present, due to the fact that no autumn herbicide has been applied or where it had been applied; a lot of the active was leached through wet conditions. As temperatures have stabilized crops will move through the growth stages very quickly and weed control must be carried out immediately. Ally Max and Compitox should be applied once weeds are growing actively and will control a range of broad leaved weeds. Compitox and Oxytril CM may be applied where awkward over wintered weeds such as fumitory, groundsel, red dead nettle and speedwells are present. Starane XL should be applied if cleavers are present but also gives very good control of chickweed and forget-me-not.

Wild oats germinate over an extended period, right through the winter and early spring months depending what depth the seed germinates from. Control should be delayed until all the wild oats have emerged. Tigress Ultra may be applied up to 2^nd node GS32 of the crop.

 I have seen some crops over the last week with very poor root structure due to the anaerobic conditions at drilling time. As these crops begin to grow the plants are yellowing and dying off. On crops with poor root development an application of Adjust may be applied to help reduce stem based lodging.

There are also signs of BYDV appearing in a few crops. This may be confused with manganese deficiency which may also be present. The initial symptoms of BYDV infection are normally seen as individual plants scattered through the crop with bright yellow upper leaves. Later, as infection spreads, larger areas of the crop become infected and affected plants can be yellow or reddish in appearance. The effects of BYDV may be exacerbated by other stress factors including adverse weather conditions such as those experienced over the winter months, and soil acidity.

Rhynchosporium is present on the older leaves of all crops and the new leaves on more susceptible varieties. A fungicide treatment should be applied now. This may be done along with the herbicide treatment.  For effective control of both Rhyncho and Mildew Punch C mixed with Talius or Midas mixed with Talius should be applied. In crops with a high yield potential a pre-formulated triazole strobilurin mix such as Mantra may be applied. Mantra is a very strong three way mix giving excellent rhynco and mildew control.

Winter Wheat

A wide range of growth stages exists from the later drilled crops which are still tillering (GS 22-25) to the early sown crops some of which are coming close to first node detectable stage (GS 31).

Septoria tritici is common on all crops especially those which are more forward. This disease is arguably the most important foliar disease of winter wheat in Northern Ireland. The lower leaves of winter sown crops are normally infected by long distance spread of air-borne ascospores throughout the winter and early spring. In the spring the lower leaves of the most susceptible varieties are infected and have actively sporulating lesions. Most disease spread to upper leaves occurs by rain splash from the lower leaves which occur during heavy rainfall. Physical spread can occur without heavy rainfall, particulary when leaves 3 and 4 overlap the upper leaves as they emerge. The T1 fungicide as well as controlling septoria and mildew should give good control of eyespot. Common Eyespot was a severe problem last year for some growers and severely affected yield. The disease causes lesions around the stem after flowering, which affect the uptake of water and nutrients into the developing grains. Some varieties are more susceptible than others and a fungicide applied at stem extension is the most effective time to protect the crop.

This T1 spray in our climate should consist of a robust conventional triazole and morpholine mix to clean up existing disease. Foil will give good Septoria and Eyespot control and if growing varieties susceptible to mildew, add Talius. Opus Team will also give excellent Septoria control but has little effect on Eyespot. Bravo in the mix also provides an alternative mode of action boosting septoria control.

The same weed control may be applied as for winter barley. Cheetah Super may be used to control wild oat. 

Winter Oats

Most crops are still at various stages of tillering (GS22-25), with low levels of disease showing at present. Growth regulation and disease control are normally applied between first and second node (GS31-32), still a couple of weeks away in most crops. Growers of conservation grade oats should consult their protocol before applying any fungicides to ensure they are allowed within the scheme.

Spring Cereals

With spring cereals now being sown and soils warming, bare fields will soon turn green. Growers need to be aware of the risk of leather jacket damage and crops should be inspected regularly as they emerge for presence of the grubs or a sign of damage as early treatment gives the most economic response.  To control leatherjackets use Dursban WG or Cyren.

Lupins

Following some reasonable experiences over the last few years some growers are again growing lupins this year to provide a homegrown protein source.  Weed control on this crop relies entirely on pre-emergent weed control.  Fields must be sprayed with Stomp within 2-3 days of drilling to prevent weed germination and avoid damaging the crop, but as with any pre-emergent sealer type herbicide, sufficient soil moisture is essential to get good results.

Grassland

It is important to remember that grassland herbicides are only effective when grass and weeds are growing actively and will not work effectively when there is a risk of low night temperatures. It is still too early to treat weeds in established grassland. Although weed control may be carried out in new leys at this time to ensure good control of seedling weeds. I will discuss grassland weed control in more detail in the next crop crack.