Call Prefix : PR-T

Call Suffix : 1971

Call Cutter : T - PlPa 1

Location : SEARCA Library

Format : TD

Publisher : University of the Philippines Los Baños (UPLB),

Publication Date : February 1971

Publication Place : College, Laguna, Philippines :

Summary : Four isolates of Phytophthora fruit rot of eggplant in the Philippines are identical to Phytophthora nicotianae var. parasitica (Dastur) Waterhouse. Morphological studies revealed that there was no taxonomic difference among them. hyphal swellings were observed in young hyphae after placing them in sterile distilled water for 1 day. Their hyphae were 3.82 to 9.09 microns in width. Chlamydospores were not produced on oatmeal agar or when submerged 1 1/2 inches in water at 20 and 26 to 30 C. Sporangia were 34.04 x 24.95, 39.09 x 32.21, 36.53 x 29.81 and 41.89 x 31.74 microns in size and their length to breadth ratio was 1.36,1.21,1.23 and 1.36 respectively. No oogonia and oospores were formed on oatmeal agar, potato dextrose broth culture, on infected eggplant fruits or in pairings between the different isolates in hemp seed broth under laboratory conditions. Zoospores of P. parasitica showed chemotaxis but not chemotropism for Dumaguete strain of eggplant fruits. More spores germinated and longer germ tubes were formed by zoospores that encysted near the fruit. The eggplant fruit extract increased the germination of zoospores. However, the germination was lower at concentrations above 5% and completely inhibited at 30% and above. Dumaguete strain of eggplant fruits rotted after 2 days when placed in Hoagland's solution containing 5,000 spores per ml. All fruits were infected after 6 days in the 5,000 and 500 zoospore concentration in both Hoagland's solution and distilled water. Zoospores germinated on the fruit surface of Dumaguete strain, after 25 minutes and entered the host after 2 hours. hyphae spread inside inter-and intracellularly. the fungus infected all tissues, except xylem vessels. The pathogen killed cells only after the latter were penetrated. The Dumaguete strain was hghly susceptible. No histologic defense reaction was observed. The first symptom of infection on young fruit became evident 18 hours after inoculation.