Evaluation of Fungicide against Taro Leaf Blight Disease Caused by Phytophthora colocasiae in Three

The taro leaf blight disease (Phytophthora colocasiae) causes a 50 to 70 percent loss of yield globally. In three agroecological zones of Cameroon, four taro landraces were planted; the Western Highlands (Bambui), Mono-Modal Humid Forest (Ekona) and the Bimodal Humid Forest (Nkolbisson) and evaluated in March and July 2018 and 2019 for taro blight intensity in four successive growing seasons. To control taro blight before and during plant development, various concentrations of copper oxide (600 g)-metalaxyl (120 g) fungicide were applied. Results showed that Phytophthora colocasiae's disease severity decreased significantly below 1.5 in all field sites with varying concentrations of copper oxide (600 g)-Metalaxyl (120 g) fungicide applied at two-week intervals. The highest taro blight severity of 7.8 was reported by the control field at Ekona. There was no substantial difference in the intensity of taro blight (P ≤ 0.05) between landraces treated with different copper oxide (600 g)–metalaxyl (120 g) fungicide concentrations. In the pre and post monitoring of taro blight in the field, lower concentrations (0.33 percent and 0.27 percent) of copper oxide (600 g)-Metalaxyl (120 g) can also be effectively used. All the landraces in the experiments in the screen house were vulnerable to P. colocasiae. Landrace L2 (red petiole small leaves) was highly resistant to P. colocasiae in all the zones and should be recommended to farmers in the three agro-ecological zones and zones with similar characteristics for optimum taro production.

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