Growing Spring Barley for the first time - never underestimate the Ramularia threat
Ramularia:
With the loss of Chlorothalonil still reverberating through the industry, growers must look to seek the next best control! But first, true understanding of the life cycle and visual symptoms of this disease must be understood. This fungus has two pathways into the plant, via seed infection or airborne spores produced on the trash and old crop debris. This disease can live within the plant through much of its life, but symptoms are not expressed until crops are stressed, due to a lack/excess of moisture or nutrition, resulting in up to 0.6t/ha yield losses.
Mature ramularia lesions can be distinguished from other foliar diseases by the ‘5Rs’
Ringed with yellow margin of chlorosis
Rectangular shape
Restricted by the leaf veins
Reddish brown colouration
Right through the leaf
Ramularia is a seed borne disease and not controlled by seed treatments, so crops with a high level of ramularia should not be farm saved. We have little varietal tolerance available, with the majority of all varieties as susceptible as each other.
So, based on the information we have, prevention is our only method of control, which starts with a sustainable rotation, where barley crops are spread over the rotation, reducing the inoculum build up. This is then finished off with a targeted chemical programme which should start at the T1 (GS30-31) timing and followed up at the T2 (GS39-45) timing. Actives should be based around Prothioconazole and CTL, which are still giving us an acceptable level of control if used in a split, two programmed approach. The multisite inclusion is exceptionally important if we are to protect our existing and new chemistry, as unlike other modes of action, multisites are not affected by resistance. In the future we will be unable to use CTL so our next best option will be Folpet mixes.