About Disease Risk Maps
On the weekly maps, red dots indicate high risk (generally 4 or more days during the week conducive to disease infection). Moderate risk (yellow dots) generally indicates between 2 and 3 days per week of exposure. Fewer exposure days indicate low risk.
Using the model of Nutter et al. (1983) with slight modifications for compatibility with the available regional weather observations, these maps highlight the risk of pythium blight infection. The index is a function of air temperature and relative humidity.