Cochliobolus

Cochliobolus

The fungus Cochliobolus sativus is the causal agent of a wide variety of cereal diseases. The pathogen can infect and cause disease on the root (where it is known as common root rot), leaf and stem, and head tissue.The fungus causes disease symptoms similar to Fusarium spp. Seedborne infection can result in seedling death although infected plants usually grow to maturity. Affected plants show brown spotting on the lower leaves and, if severely affected, can show stem-base rotting and poorly filled heads. The pathogen perennates both externally as conidia and internally as mycelium in the seeds.

Disease Cycle: Along with the germination of the diseased seeds, the causal organism becomes active. This is the starting point of the disease.   Maximum development of symptoms appears when the leaves remain wet for more than 18 hours with a mean temperature greater than 18˚C. Under favourable conditions conidia are formed which are transmitted by rain splashes and wind. Conidia on germination produce a germ tube, the germ tube then swells to produce appressorium from which infection hyphae are developed. The infection hyphae then enter the host tissue. Immediately after the entrance in the host tissue, the infection hypha divides rapidly.

Disease Control:  Disease incidents can be controlled in a number of ways. Integrated pest management is by far the best method of controlling the pathogen. This approach utilizes a broad-based approach that integrates a range of practices for economic control of pests. It aims to suppress pest populations below the economic injury level.  Selection of disease free seeds and utilizing proper fertilization technique can also be used to effectively control severity.  Seeds are one of the important sources of primary infection. Therefore, seed treatment with a suitable fungicide reduces the carry over inoculums potential.  Macro and micronutrients have long been recognized as being associated with size, quality, and yield of crops. Macro and micronutrients helps plants to withstand pathogen attack at the time of stressful conditions.  Besides increasing grain quality, the main objective of nutrient application is also to protect crops against pathogens.   Crop rotation favours beneficial soil organisms as well as promotes better plant nutrition.