Yield of potato as influenced by crop sanitation and reduced fungicidal treatments [in Cameroon]

The effects of crop sanitation and reduced sprays of Ridomil plus (12 percent metalaxyl + 60 percent cuprous oxide) on the control of potato late blight caused by Phytophthora infestans were evaluated in two field experiments in 1993 in Dschang, Cameroon. In the first experiment, sanitation (five weekly removals of blighted leaves) and two fungicidal treatments were initiated from first symptoms. In the second experiment, both fungicidal sprays were made at varying rates. Marketable yields increased by 50 percent in sanitation-treated plots, by 94 percent in plots sprayed with Ridomil plus (2.24 kg a.i./ha), or by 55 percent in those exposed to both control methods. The fungicide equivalence of the sanitation treatment was two sprays of Ridomil plus at 0.76 kg a.i./ha. These results suggest that proper removal of diseased leaves or reduced fungicidal protection may be an effective late blight control method in potato farming.