Threats in the Field
Throughout NZ, scald and leaf rust have heavily infected barley crops as a result of the mild, wet winter. No doubt, early-season fungicides applied at GS30 and GS32 will be controlling these diseases. Nevertheless, this does not mean you can let your guard down. With high levels of inoculum ready and waiting to attack in the bottom of the crop canopy, a follow-up GS39 fungicide will be essential.
In addition, the threat of Ramularia leaf spot (RLS) makes this application even more important. At the moment RLS cannot be easily seen on the crop. This, however, does not indicate a disease-free crop, as the disease grows inside the plant having first infected it via the seed.
True, you might be able to find a few RLS lesions on the dying older leaves, but the first real signs RLS has infected your crop won’t become visible until late November. At this point, RLS causes rapid death of the upper leaves leading to premature crop death and reduced yields. By then, it is simply too late to take action.
Take Control of Your Crops
To control RLS, it is vital that Aviator® Xpro is applied between GS39 and GS49 (flag leaf emerged to awns emerging). During Bayer trials carried out in Canterbury, the best control of RLS resulted from a GS39 application.
What’s more, applying Aviator® Xpro between GS39-49 (as is seen in the Barley Spray Programme below) will also control scald, net blotch and leaf rust that would otherwise infect the crop.
From the crops inspected to produce this Disease watch, we found that for most autumn/winter planted barley crops, GS39-49 is now!