Rice
Bakanae and Foot Rot
Gibberella fujikuroi
Fungus
In a Nutshell
- Thin plants with yellowish green leaves and pale green flag leaves.
- Abnormal stem elongation. Less tillering and rooting of rot stem joint.
Rice
Symptoms
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, sterile, or empty grains. In those plants, the flag leaf is noticeable by its elevated and more horizontal orientation.
Recommendations
Organic Control
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.
Chemical Control
Always consider an integrated approach with preventive measures together with biological treatments if available. Soaking seeds in a fungicide solution containing triflumizole, propiconazole, prochloraz (alone or in combination with thiram) for five hours has been shown to be useful. Seed treatment with sodium hypochlorite (bleach) is also effective at reducing the incidence of this disease. Spraying of the compounds above during vegetative stage for two times at weekly intervals also helps to control the disease.
What caused it?
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 of 30 to 35°C favour the development of the disease.
Preventive Measures
- Use clean seeds to minimize the occurrence of the disease.
- Check the resistant varieties available.
- Monitor your seedlings and avoid planting palish, albino plants.
- Avoid over-fertilization with nitrogen-rich fertilizers.
- Deep plowing of fields before planting helps to expose the soil to UV light.
- Destroy the stubbles of the previous crop by plowing before sowing.
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