In the early stages, blackened areas develop at the base of a few grains per spike. Little by little, the grains are emptied of their content, and partially or wholly filled by a black powdery mass. The grain does not swell in the process and the glumes usually remain intact. As the disease progresses, more grains on other spikes are affected. When crushed, these grains emit a smell of rotting fish. However, the number of grains smutted is rarely exceeding 5 or 6 per spike. Infected plants may be dwarfed. The disease has only minimal effects on grain yield, but seeds may be refused because of quality problems or simply because of the presence of the spores.
Karnal bunt is caused by the seed- or soil-borne fungus Tilletia indica. The fungus can survive up to 4-5 years in the soil. The spores present in contaminated soils or plant residues spread to healthy plants and inflorescences. Infection can take place throughout the flowering period but plants are more susceptible during the emergence of spikes. The fungus colonizes the developing seeds and gradually empty them of their content. Climate is an important factor in the development of of symptoms. Humid weather conditions (>70%) and temperatures between 18 and 24°C during grain formation are favorable for the progression of the disease . The spores can also be dispersed via farm equipment, tools, clothes and even vehicles.
Sorry, we don't know of any alternative treatment against Tilletia indica . Please get in touch with us in case you know of something that might help to fight this disease. Looking forward to hearing from you.
Always consider an integrated approach with preventive measures together with biological treatment if available. No seed treatment is 100% effective, but there are several treatments that inhibit the growth of the fungus and the damage to grain. Fungicides based on carboxin-thiram, difenoconazole, mefenoxam or tebuconazole can effectively eliminate the air-borne infection of fields.
Use seeds from healthy plants or from certified sources.,Grow resistant varieties if available.,Avoid cultivation of alternative hosts in the surrounding fields.,Implement a wide crop rotation with non-host plants for up to 5 years.,Adjust sowing time to avoid the formation of heads under optimal weather conditions for the fungus.,Improve field drainage and avoid excessive irrigation at the time of flowering.,Avoid excessive fertilization with nitrogen.,Restrict the movement of farm machinery and soil from contaminated fields.,Plastic mulch can be used to raise soil temperature and reduce fungal spreading.