Black Sigatoka Risk Model
Two Black Sigatoka Risk Models
One Model (Sigatoka risk by ET) is basing on a) The determination of the evapotranspiration (sensors needed: temperature, rel. humidtiy, wind speed and globar radiation). This model is based on the work of Ganry, J. & Meyer,J.P. (1972): La lutte contrôlée contre le Cercospora aux Antilles. Bases climatiques de l’avertissement. Fruits 27(11):767-774. In this study the ETpiche was used for assessing the climatic favorability to sigatoka. Field.Climate uses the "Penman Montheith" equation (is the most general and widely used quation for calculation reference ET) instead of ETpiche. If the accumulated Evapotranspiration of the last 7 days is:
> 40 mm No Risk
> 30 mm Low Risk
> 22 mm Average Risk
< 22 mm High Risk (we assume that on this low ET0 it is raining and very wet, the sky is cloudy...??)
b) The other model (Sigatoka Risk by Infection) uses the results of the infection model to prove for infections and the range of precipitation during this infection to assess the importance of this infection events. The amount of rain during an infection is responsible for the distributon of the spore. As more equal the spores are distributed on the susceptible tissue as more tissue will become infected and as bigger the spread out of the disease. An infection without any rain has the disease severity value of 1. An infection with less than 2, 5 and 10 mm of rain has the severity value of 2, 3 or 4. If there has been more than 10mm of rain the severity value is 5. The risk indication is done by the accumulation of these severity values for the last 4 days. If we accumulate 0 there is no risk. If we accumulate less than 4 there is a low risk of Sigatoka. If we accumulate between 4 and 12 there is a moderate risk and if we accumulate more than 12 within the last 4 days the risk is stated to be high.
For more Information about the Sigatoka Infection model click here. For more Information about the Black Sigatoka Spray Evaluation model click here. For more Information about the Black Sigatoka Biology click here.