Eyespot and Wheat

DSV have produced a variety called Chilton with a score of 8.5 for eyespot, but what is eyespot and how important is this resistance?

Eyespot (Oculimacula yallundae & O. acuformis) and Wheat

Eyespot is a fungal pathogen of wheat but will also attack barley, rye, oats and triticale. Eyespot attack is often misjudged as growers seldom check the stem bases of their crops after growth stage 77 when the ears have almost filled. It is at this point when eyespot can be observed. Eyespot can cause yield losses of up to 30% and in severe cases lodging can occur bringing problems at harvest time and reducing Hagberg Falling Numbers.

Eyespot can be seen as a brown smudge at the stem base which can penetrate more than one leaf sheath (Sharp eyespot and Fusarium spp. will only be seen on the outermost sheath). As the season progresses, the naming of this disease becomes more understandable as the smudge develops into an eye-shaped lesion with a dark perimeter and black centre. Later in the season, plants suffering from eyespot can be identified by their bleached ears as nutrients are cut-off at the stem base.

Eyespot is more of a problem in second wheat and becomes severe with continuous cereals due to the build up of inoculum year after year. Conidia on the soil surface or crop debris reach the developing wheat by rain-splash. Once the fungi have attached themselves to the leaf sheath, mycelia begin to attack the inner parts of the stem where economic damage starts to occur. In response to this infection, wheat will increase production of callose, a plant polysaccharide which makes it more difficult for the eyespot mycelium to move within the stem. The plant also produces the toxin, hydrogen peroxide as well as expressing a number of pathogenesis-related genes. It is the level of expression, combination and variants of these genes which bring about the differences in wheat varietal resistance to eyespot and other diseases.

At DSV we breed wheat varieties by selecting plants which show resistance to major diseases such as eyespot. Our latest group two winter wheat, Chilton, has outstanding resistance to eyespot with a high yield, making it an excellent choice for a first or second wheat.