Rice Blast Model
The Rice Blast Infection model points out date time and severity of infection. Light infections finish faster than severe infection. For severe infections it will need higher temperatures and longer leaf wetness periods. The severity of infection is rated by the possibility of a light or a sever infection and the amount of rain at the initial of the infection. Higher rain amounts with higher intensities will lead to a better distribution of spores. The model goes back to publications of Yoshino 1974, 1979 and Hashimoto et al 1984.
Infection starts with rain smaller than 4 mm and leaf wetness. The infection progresses in dependence of temperature. The graphs below is showing the relation in temperature and leaf wetness period to fulfil a light (level 1) and a severe (level 2) infection. On base of this curves the model indicates the possibility of infection by this disease. If the disease progress curve reaches 100% the light or severe infection is finished and symptoms are expected after 4 to 5 days.
The severity is depending on temperature during infection and on precipitation. The graph shows the relation of severity and temperature during infection.
The rice blast model points out infection date and infection severity. This information is valid to improve the applied spray program. In a preventative spray program plant growth is reducing the protected plant surface within days. An infection which takes place immidiatly after a preventative spray will be covered perfectly. If an infection will be 6 or more days after the last spray disease control can be sustainable reduced by the high volume of uncovered leaves. In this case a curative spray will be indicated to ensure the success of disease control.