Ramularia is a fungal disease of barley, which impacts late in the growing season.
Teagasc scientists have recently completed a number of trials, designed to identify how best to deal with ramularia in the wake of the EU’s decision to ban the fungicide (chlorothalonil).
Tillage specialist Deirdre Doyle, based at Teagasc Oak Park, spoke at the recent National Tillage Conference.
She confirmed that stressed crops are more likely to show symptoms.
“Once symptoms develop on upper leaves, post-flowering, treatment is not effective,” she said.
Yield losses related to the reduction of photosynthetic area can range from 0.5t/ha to 1.0t/ha.
According to Doyle, ramularia can come into a crop through infected seed. Some infections can be caused from airborne sources and debris left by cereal crops.
Symptoms generally develop on upper leaves. These can also progress on to the ears and the awns.
Ramularia is the foliar disease that you don’t see until it is too late to do anything about it.
“Over the past 20 years, it has grown into a very serious disease threat, particularly now since we have lost the use of chlorothalonil.”
Doyle went on to make the point that tillers must be both created and protected, in order to secure maximum barley yields.
“High tiller numbers must be created, which means that disease protection at the tillering stage is important,” Doyle added.
“Successful ear filling is also important.”
Fungicide applications at tillering can deliver a yield response of 0.8t/ha on spring barley crops. Applications at around growth stage 40 can deliver a yield benefit of a similar magnitude.
“Ramularia pressure can vary from year to year,” Doyle said.
Teagasc is currently looking at alternative chemistries that will impact on ramularia.
A comprehensive trial was carried out across sites at Oak Park and Kildalton in 2019. Chlorathalonil was used as the control at both locations.
However, the level of control was not as good as that generated by chlorothalonil. The work also indicated that multi-site fungicides do not give the same level of control as prothioconazole, given the conditions that prevailed in 2019.
Resistance issues seemed to impact on the effect of SDHIs (succinate dehydrogenase inhibitors) in terms of the ramularia control they provided.
Selecting for variety resistance is not an option when it comes to coping with ramularia.
“Ensure that adequate nutrition is available to ensure the crop is not stressed. Build a fungicide programme that will best protect the crop,” she concluded.