Bakanae and Foot Rot
Bakanae is conspicuous as a seedling disease but it can also be observed at all stages of plant growth. The fungus infects plants through the roots or crowns and then grows systemically within the plant through the stem. If they survive the first stages of the infection, the seedlings develop into abnormally tall plants (often several inches) with pale, thin and dry leaves, and with fewer tillers. The inner side of the stem becomes rotten and new roots develop from the upper nodes of the stem. Brown spots develop on the stem of infected plants.If the plants survive to maturity stage, they develop partially filled grains, sterile, or empty grains. In those plants, the flag leaf is noticeable by its elevated and more horizontal orientation.
Bakanae is a seedborne fungal disease. The disease occurs most frequently when infested seeds (i.e., seeds covered in fungal spores) are used, but also can occur when the pathogen is present on plant material or in the soil. It spreads through wind or water that carries the fungal spores from one plant to another. Bakanae can also be transmitted during farm operations such as harvesting infected plants allowing fungal spores to spread to the healthy seeds, and soaking seeds in water that contains the fungus.High temperatures 30 to 35°C favour the development of the disease.
No biological treatment against this disease is known to this day. Salt water can be used to separate lightweight (infected) seeds from healthy ones during soaking.
Always consider an integrated approach with preventive measures together with biological treatments if available. Applying a fungicide containing benomyl or benomyl-t (at 1-2% of seed weight) to treat infested seed can be effective. Soaking seed in a fungicide solution for five hours has also been shown to be useful. In cases where resistance to benomyl occurs, use a fungicide that contains triflumizole, propiconazole, prochloraz or a combination of thiram and benomyl.