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Leaf Spot Disease of Kaatoan Bangkal (Anthocephalus Chinensis (Lamk.) A. Rich. Ex Walp.) at Seedling Stage
Thesis Abstract:
The study on leaf spot disease of kaatoan bangkal (Anthocephalus chinensis (Lamk.) A. Rich. ex Walp.) at seedling stage was conducted at the Makiling Experimental and Demonstration Forest (MEDF) nursery in Los Baños, Laguna on 16 July 1981-22 June 1982.
This pathological problem caused severe leaf spots on seedlings of A. chinensis, resulting in stunted hrowth and premature falling of leaves. Approximately 100 percent of the observed seedlings in the nursery were in different stages of the disease with calculated infection index of 71.47 percent. The visual symptoms of the disease were circular spots, very irregular, yellowish to brownish with apparent gray to black concentric rings similar to contour lines.
The fungus produced hyaline and granular mycelium when young, and five-celled Olivaceous conidia with two ir three setae in the superior hyaline cell. The inferior hyaline cell tapers into an erect pedicel. The causal organism of the disease closely resembled the Pestalotia annulata Berk. and Curt.
The fungus grew and sporulated better in all the tested media except in water agar. It grew on a wide pH range of 3-10 but optimally on pH 6.
The temperature range for the growth of the fungus was 10-30°C with maximum growth at 25°C. The thermal death point was between 36°C and 40°C.
Light is essential for the sporulation of the fungus.
Maltose and sucrose favorably supported the growth and sporulation but ammonium nitrate was poorlyu utilized by the fungus.
The fungal pathogen might be mechanically transmitted by the two coleopterous pests of kaatoan bangkal.
Systematic fungicides such as Benlate, Fungitox, and Topsin M were promising chemicals for the control of the disease.
