Mild weather and a lack of eyespot resistant winter wheat varieties on the AHDB Recommended List (RL) could mean growers may well see the disease in their crops this spring, according to David Robinson, technical specialist, Frontier.
He says: “The one thing I think growers need to keep an eye on at the moment is eyespot. Although it has not been a big disease for 2-3 years, and we have not had a lot of eyespot weather, if we have a spell of wet weather, certainly during late February and most of March, not only will septoria become more important for everybody, eyespot might get a bit of a push as well.”
This is partly down to less focus on eyespot resistance, says Mr Robinson.
“Although we appear to have a lot of varieties on the RL with a 6+ rating for septoria, which is really good news, a lot of varieties on the RL are also quite weak for eyespot, with only a 4 rating, which is not outstanding.”
However, Dr Rumiana Ray, Associate Professor in Crop Pathology, University of Nottingham, says this is likely to be down to the fact that fungicides give good control of eyespot, so other diseases will be of greater priority to growers.
“Resistant varieties for Septoria are crucial and take priority over eyespot because fungicides are less effective and there is fungicide resistance in the population of Zymoseptoria tritici. However, we still have effective fungicides against eyespot.
“Resistance is preferred control method for any disease including eyespot, but generally fungicides used against Septoria have a broad-spectrum activity and will target eyespot as well. Septoria, rusts and Fusarium head blight are the key diseases for wheat growers and eyespot probably comes forth behind them on the list of disease targets.”
Whether eyespot establishes is dependent on the spring weather says Dr Ray. If temperatures remain mild and frequent rainfall occurs, the disease will develop, particularly in early drilled cereals.
“Eyespot develops well between 4-15C, but in terms of infection you need rainfall to splash the spores onto the coleoptile and establish the pathogens on the seedlings as early as possible. Over the winter period, as long as you’ve got infection already within the developing plant stem, the disease will develop.
“What would matter for disease severity in the spring is the establishment of the eyespot lesions in april/may. If we still have a relatively mild temperatures with high moisture then that will help. However, if it is too warm and there is infrequent rainfall then you may lose the disease on the outer leaf sheaths which will prevent lesion establishment on the stem.”