TY - BOOK AU - Deiparine, Karen Louise K. TI - Etiology of the orange spot disease on cladodes of dragon fruit [hylocereus undatus (haworth) britton and rose] PY - 2009/// KW - SMIARC (Southern Mindanao Integrated Agricultural Research Center) KW - Davao City KW - Philippines KW - Department of Agriculture KW - Manambulan, Tugbok District, Davao City KW - Pathogenicity KW - Morphology KW - Cladodes KW - Pitahaya KW - Dragon fruits KW - Plant wilting KW - Fungicides KW - Hylocereus undatus KW - Cultivation KW - Assay efficacy KW - Southern Mindanao KW - Undergraduate Thesis KW - BIO200, KW - BSB N1 - Thesis (BS Biology) -- University of the Philippines Mindanao, 2009 N2 - Thielaviopsis sp. was consistently isolated from dragon fruit cladodes [Hylocereus undatus (Haworth). Britton and Rose] infected with orange spots bordered by yellow halo. Reisolation of the causal organism from inoculated cladodes confirmed the association of the fungus with the disease. The reisolated cultures have dense, white, filamentous mycelia that turn black after a few days. Under microscopy, its hyphae, which measure 59.18 (22.25) m long and 9.61 (1.48) m wide, are septated, thick-walled, hyaline, long and narrow to broad. It produces two types of conidia: 1) hyaline, cylindrical endoconidia measuring 9.40 (2.08) m long and 4.35 (1.25) m wide; and 2) pigmented, catenulate, subrectangular to circular aleurioconidia measuring 9.53 (1.89) m long and 6.1 (1.06) m wide. Colony growth and spore production of Thielaviopsis sp. in vitro were affected by several factors. Light was a key stimulator on the mycelial growth and spore production of Thielaviopsis sp. Colony growth was profused at pH 5.62 than on pH 6.62 and 7.62, but no differences on the three pH regimes were noted in terms of spore yield. Thielaviopsis sp. also preferred a higher temperature set-up (room temperature) than under a daytime air-conditioned environment mainly because its host normally lives in tropical and subtropical environments where temperatures are relatively high. An assay of various fungicides revealed that the growth of Thielaviopsis sp. was successfully inhibited by mancozeb event at concentrations below its generally recommended rates ER -