Etiology and chemical control of the floral browning disease of sampaguita (Jasminum sambac (L.) Aiton) in Sta. Cruz, Laguna

Date

8-2015

Degree

Bachelor of Science in Agriculture

Major Course

Major in Plant Pathology

College

College of Agriculture and Food Science (CAFS)

Adviser/Committee Chair

Johnny F. Balidion

Restrictions

Restricted: Not available to the general public. Access is available only after consultation with author/thesis adviser and only to those bound by the confidentiality agreement.

Abstract

Farmer's field planted with sampaguita in Sta. Cruz, Laguna has experienced to have an outbreak of floral disease that has significant reduced famer's yield in the past years. Floral "browning" disease which resulted to the reduction of the quantity and quality of the harvested flowers was studied. Symptoms observed were browning of the petals and eventually abortion of the flower, foliar spots with chlorotic halo, and chlorotic spots on the leaves. Isolation and pathogenicity test was done to identify the suspected pathogen of the floral "browning" disease. Isolation showed that was fungi that cause the disease. Symptoms observed on the sampaguita farms in Sta. Cruz, Laguna which are in the aerial parts of the plant specifically leaves and flowers. Macromorphological characterization of the isolated fungal pathogen suggests that it belongs to the genus Colletotrichum sp. Three possible Colletotrichum isolates that were pathogenic to sampaguita were isolated namely, L1, L2 and L3. Isolate L1 has measurements of conidia: 10-18µm, hypha: 16-23 µm wide and conidiophores: 20-40 µm long. Isolate L2 has measurements of conidia: 10-13 µm x 2-5 µ m, hypha: 15-24 µm wide and conidiophores: 23-45 µm long. Isolate L3 has measurements of conidia: 8-15 µm x 2-7 µm, hypha: 18-23 µm wide and conidiophores: 30-45 µm long. Difference in the growth rate of the isolates was analyzed using ANOVA and mean growth rate was compared using LSD at a=0.05. Growth rate of isolate L1 and L2 were not significant with 6.79 mm growth/day while L3 is significant different with 7.39 mm growth/day. The three isolates are similar are similar in terms of growth patterns which produces white mycelia with orange pigmentations that forms concentric growth patterns on PDA. Fungicides namely, Tebuconazole, Difenoconazole, Azoxystrobin and Mancozeb, were evaluated for their effectiveness to the three fungal isolates using in vitro plate assays and plot experiments in farmer's fields. Tebuconazole and Difenoconazole completely inhibited the growth of the three fungal isolates while minimal growth was observed in Azoxystrobin and Mancozeb treated in in vitro. In fields trials Azoxystrobin has the lowest percent disease incidence of 38.24% while Tebuconazole has the highest percent of disease incidence of 44.03%. All fungicides are significantly effective in controlling the disease in vitro and in field condition compared to water using LSD at µ=0.05.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 993.5 2015 A3 /G37

Document Type

Thesis

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