Weekend rainfall welcome
Published 18/05/2010 | 05:00
The increase in temperatures and general improvement in the weather will boost cereal growth and help struggling crops like beet and maize. Rainfall over the weekend was also welcome as the soil moisture deficit was getting serious in many places. Soils are showing a deficit of between 20mm and 30mm as of last week. Most growers would agree that an inch of rain at this stage would be welcome.
On the other side of the equation, all the dry weather has reduced the levels of disease in crops. In April, rhyncho levels in winter barley was high, especially in Saffron. The combination of the T1 fungicide and subsequent dry weather stopped further rhyncho spread and crops are clean at the moment, with very little visible disease. Many crops are due their final fungicide this week. Awns are out on most crops, with the more advanced crops at the heading out stage.
Many crops look shorter than normal and some have thinned out more than I would like. It could be argued that many of these crops will not need a growth regulator as the risk is greatly reduced. However, most crops will probably end up close to their normal height so if you are pushing the crop and it has maintained its density then consider applying a late growth regulator. Cerone 0.6-0.8l/ha can be used up to GS 51 (awns emerged). Where the head is out of the leaf sheet (i.e. where any part of the grain sites are visible) its too late for a late growth regulator.
Check the crop before applying the final fungicide as areas which received a good dash of rain about two weeks ago may now have increased levels of disease. Many growers in the southeast have received little or no rain since early April.
Rainfall a couple of weeks ago may have increased disease levels in the crop. The final fungicide application will contain chlorothalonil (Bravo), and products such as Fandango, Allegro Plus and Venture will perform well at this timing. Keep an eye out for value with pre-formulated products containing chlorothalonil and strobs such as Amistar Opti and Credo, but you should add a triazole (Proline or Opus) for good control of wet weather diseases. Bear in mind Ramularia is best controlled preventatively with chlorothalonil, so timing of the final application should be targeted closer to awns just emerging rather than head fully out.
Many growers have delayed the application of weed herbicides to crops until this week hoping for better growing conditions. Almost all cereals should receive the herbicide this week if it's not already applied. Include an aphicide to April sown crops.
Check the growth stages of March-sown crops as many of these crops have grown more than you might have thought possible over the past 10 days and are now at stem extension. Where these crops are past first node, switch from hormone products (CMPP, Dicamba, etc) to Galaxy or fluroxypr (Starane). Use robust rates of these SU products (Ally Max, Biplay) and of the mixer products to control advanced weeds.
So far disease levels in spring barley are low. However, Snakebite and Centurion had low levels of rhyncho early on and these lesions will act as a reservoir for further infection following the rain over the last few days. Where crops are clean, a low-rate fungicide such as Proline, Stereo or Opus will suffice. Keep an eye on Frontier for mildew before you apply the fungicide.