Effect of temperatures and rainfall variations on the development of coffee berry disease caused by Colletotrichum kahawae

Arabica coffee production in Africa is greatly affected by coffee berry disease (CBD), caused by Colletotrichum kahawae. This disease is specific to green berries and leads to 60–80% harvest losses under conditions conducive to the development of the pathogen. Agricultural practices, combined with chemical control involving 8–12 annual fungicide applications, are known to be very effective against CBD, especially in high altitude regions (>1600 m) where the most damaged coffee farms are found. Temperatures and rainfall may be key factors in the development of CBD epidemics. Therefore, an epidemiological study was conducted on smallholding coffee farms in Cameroon, to assess the dependence of disease development on variations in these climatic factors. Cross-correlations between disease severity and climatic parameters recorded weekly were estimated over two successive years (2004–2005), revealing a significant increase in disease severity in line with decreasing temperatures (minimum or maximum). They also indicated a large variation in disease severity depending on the number of raining days during berry growth. However, no significant correlation was found with the quantity of rainfall over the two years of observations. Thus, temperatures and rainfall distribution appear to be the key climatic parameters that favor the development of CBD epidemics. These results suggest that temperature and rainfall parameters might be very useful for establishing predictive models to optimize effective CBB control in areas with a high disease incidence.

► Temperature and rainfall are the key factors of coffee berry disease epidemics.
► Decreasing temperature favors the disease severity.
► A predictive model was built and could help for a better management of the disease.