Dope grain

The fungus Gloeotinia temulenta is the causal agent of the disease commonly referred to as dope grain. This pathogen is a member of the Ascomycota division and targets the ovaries of various grass species, replacing healthy kernels with sclerotia that contain toxic compounds, primarily loline alkaloids, which cause neurological symptoms in mammals.

The host range of this disease is quite broad, affecting economically significant crops such as wheat, rye, barley, and oats, as well as many forage grasses. Wild grasses, particularly ryegrass (Lolium temulentum), act as the primary inoculum sources, facilitating the survival and spread of the fungus in agricultural landscapes.

Symptoms of the disease are characterized by the transformation of the grain within the glumes. During the maturation stage, the sclerotia develop inside the florets. Unlike ergot (Claviceps purpurea), the sclerotia of Gloeotinia temulenta are similar in size, shape, and color to healthy seeds, making physical separation during cleaning processes extremely challenging.

The development and spread of the pathogen are highly dependent on climatic conditions during the flowering phase of the host plants. Optimal conditions include moderate temperatures and frequent rainfall or high relative humidity. These factors promote the germination of apothecia in the soil, which release ascospores that are subsequently disseminated by wind to susceptible flowers.

The primary damage caused by this disease is the reduction in grain quality and the risk of toxicosis. Consumption of contaminated grain leads to dizziness, nausea, and motor coordination problems in humans and animals. Effective control strategies include the use of disease-free certified seeds, cleaning grain to remove sclerotia, crop rotation, and strict management of wild grass weeds within and around fields.