In vitro efficacy of fungicides for control of phytophthora nicotianae a causal organism of pineapple heart rot disease in Uganda

Abstract

Pineapple heart rot disease (PHRD) caused by Phytophthora nicotianae is a threat to pineapple industry in Uganda. Currently, there is uncertainty in the management of the disease. Elsewhere, fungicides are used for management of Phytophthora diseases. The objective of this study was to determine in vitro efficacy of fungicides for the control of Phytophthora nicotianae causing PHRD. Twenty isolates of Phytophthora nicotianae were tested for sensitivity to Metalaxyl, Victory 72 powder and Fosetyl Al on 10% V8 media at 0.1g L^-1, 0.01 L^-1 and 0.001 g L^-1 in vitro. All isolates were sensitive to Metalaxyl and Victory 72 powder at 0.1 g L^-1 with no growth in the plates. However, there was a significant (P<0.05) difference in isolate growth at 0.01 and 0.001 g L^-1 Metalaxyl and Fosetyl Al. At 0.01 g L^-1 Fosetyl Al, the highest and lowest colony diameters were 71.89 mm (MAS 01) and 17.61 mm (MUK 01) compared to 77.44mm (MAS 01) and 0.00mm (MUK 01; MAS 02) in Metalaxyl amended plates respectively. Based on this result, it was concluded that Metalaxyl and Victory 72 powder were effective in suppressing Phytophthora nicotianae. However, determining the efficacy of these formulations under field conditions is recommended.