Do coffee varieties and shade trees matter for management of leaf rust disease in India? Evidence for household farmers.

摘要

This paper assesses how Arabica coffee varieties and shade trees affect the management of coffee leaf rust (CLR) by chemical controls (Bordeaux mixture and systemic fungicides). All estimations are based on a new set of sample household survey data involving 575 Arabica coffee farmers (comprising 90% of smallholders) and collected in the traditional coffee growing regions of India. Estimates show that, with no shade trees, the probability of management of CLR by chemical sprays is highest for farmers who cultivate the S.795 variety, and lowest for those who grow the Selection.9 variety. This result is shown to be (1) valid if more than one variety is grown by the same farmer and (2) consistent with the requirement of more chemical controls for CLR-susceptible varieties than for CLR-resistant varieties. Further, of the four main structures of shade trees canopy identified, mixed shade canopy (a combination of various tree species with different height) is the structure that has the least influence on chemical control. When coffee varieties and shade trees are considered together, Selection.9 variety under mixed shade canopy appeared as the best combination for an effective management of CLR. These results unambiguously show that coffee varieties and shade trees do matter for farmers' management of CLR by chemical controls. The overall approach and results have implications for other coffee growing countries in Asia, Central and South America and Africa.