Rice Blast

Rice Blast

 

(also rotten neck), a serious disease of rice caused by the imperfect fungus Piricularia oryzae. Rice blast occurs in rice-growing regions throughout the world. It is characterized by the formation of variously shaped and colored spots on the leaves, leaf sheaths, stem axils, panicles, and seeds. The leaves die, the stems break, and the panicles dry prematurely or form undersized seeds. The disease causes greatest harm during heading and flowering. Harvest losses are 15 to 40 percent, and the quality of the grain is significantly lowered. When the disease is epiphytotic, the plants die.

The causative agent of rice blast has several generations during the vegetative period and spreads by means of conidia; it winters in the form of mycelium on post-harvest remains (one to three years) and in seeds. The disease develops when there is high air humidity (no lower than 88 percent) and high temperature (15° to 35°C). The infection may be transmitted with irrigation water. Wild rice and other grains may be reservoir hosts of the disease. Control measures include cultivating resistant varieties, plowing under live remains, burning the stubble on areas with severe development of the disease, and treating infected plantings and rice seeds with fungicides.

REFERENCE

Peresypkin, V. F. Sel’skokhoziaistvennaia fitopatologiia. Moscow, 1969.

N. A. TIKHONOVA

References in periodicals archive ?
Tissue-adapted invasion strategies of the rice blast fungus Magnaporthe oryzae.
Identification and characterization of rhizosphere fungal strain MF-91 antagonistic to rice blast and sheath blight pathogens.
Rice blast caused by the fungal pathogen Magnaporthe oryzae is one of the most destructive diseases of rice threatening the sustainability of global food production.
The first was realized at November, 22, 2012 with Cioermetrin (100 mL [ha.sup.-1]) for larvae control and with the insecticide Tebuconazole (0.75 L [h.sup.-1]) for rice blast neck preventive control; the second application was carried out two months later using the insecticide acephate (1 kg [ha.sup.-1]) with the fungicides tricyclazole (0.3 kg [ha.sup.-1]) and Tebuconazole (0.75 L [h.sup.-1]).
Several problems including vulnerability to rice blast a weak ability of the seedlings to emerge through the soil surface and low vegetative vigor limit the widespread adoption of aerobic rice.
Screening of rice germ plasm against Pyricularia oryzae the cause of rice blast disease.
In the same way, weather conditions such as the minimum and maximum levels of temperature, humidity and rainy days can help estimating the behavior of rice blast [10].
The technique is particularly effective at reducing loss from rice blast disease, a destructive fungus that causes damage on panicles and leaves, killing them before rice grains form, he added.
Similarly, he said, the growing two or more crops in proximity helps reduce disease outbreaks and the technique is particularly effective at reducing loss from rice blast disease, a destructive fungus that causes damage on panicles and leaves, killing them before rice grains form.
In the first season, rice plants were affected by drought while in the second, they were infested with rice blast fungus.