Effects of soil-applied metalaxyl on feeder root rot of durian and sporulation of Phytophthora palmivora.
1993
Lee Boun Siew | Teoh Ho Peng
In a recent study in Selangor, 15-year old mature clonal durian trees, mostly severely affected with stem canker and FRR, were treated with metalaxyl. Untreated trees acted as control. Soil below the canopy was treated at 3-monthly intervals with Ridomil 5G* (5 percent granule) at 0.5 kg/tree and Subdue 250 EC* (liquid formulation) at 2 g active/m* canopy/tree. Because efficiency of fungicide uptake depends largely on the presence or absence of weeds, some of the durian trees were also cleared of weeds with Basta* (glufosinate-ammonium) 7 days before each fungicide application. Soil and root samples, up to a depth of 15 cm, were sampled from each tree at 1, 4 and 8 weeks after each fungicide application. Results showed that Ridomil 5G* applied on clean-weeded soils effectively control FRR. On unweeded trees, the effect of Ridomil 5G* was only evident after the third application. The liquid formulation has little or no effect on FRR control, probably due to its rapid mobilitly suppress sporangial production of P. palmivora when the fungus was grown in 50 percent soil extracts obtained from the treated soils. Granulat metalaxyl applied on clean-weeded soil thus appears promising for the control of FRR.
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