Epidemiological study and non-pesticide control of anthracnose disease of water caltrops
Date Issued
2016
Date
2016
Author(s)
Lin, Yen-An
Abstract
Water caltrops (Trapa taiwanensis Nakai) is a common annual aquatic crop in Guan Tian, Tainan. It adapts well in wetland like swamp or paddy areas. The most common diseases affecting water caltrops are anthracnose and sclerotium rot. The anthracnose disease of water caltrops is caused by Colletotrichum gloeosporioides Penzig. On water caltrops, the anthracnose can cause black spot symptoms that can coalesce into big lesions on leaves, petiole and fruits. This study is aimed to confirm the pathogenicity of anthracnose fungi on water caltrops and to investigate the epidemiology of this disease in Guan Tian area. Some herbal material extracts and antagonistic microorganisms are also evaluated for their potential for controlling this disease. Through the pathogenicity tools and molecular identification, we accomplish the Koch’s postulates of this disease. Culturing this pathogen at different temperatures showed that the pathogen grows best at 25℃. The epidemiological study from 2014 to 2015 showed that the disease occurred after a long period of raining summer season and may continue to the winter time. The correlation coefficient between last-monthly rainfall and disease severity in 2014 and 2015 are 0.9371 and 0.9297, respectively. If we combine the favorable rainfall, temperature and wind speed in together, the correlation coefficient between favorable hours and the disease severity in 2014 and 2015 can be as high as 0.9485 and 0.9271, respectively. Results indicated that the disease severity is positively correlated with favorable temperature, high wind speed and high rainfall. The non-pesticide control study showed that antagonistic microorganism had better effectiveness than herbal extracts. Water extracts of all herbal material showed low control rate on PDA. Although ethanol extracts of all nine herbal material showed significant inhibition rate in spore germination and mycelial growth tests, they didn’t have good effectiveness in the pot plant test. Both Bacillus subtilis and Streptomyces sp. YU01 has about 45 % control rate in pot plant test, when applied 3 days before inoculation with pathogen. Whereas Trichoderma asperillum expressed only about 30% control rate in pot plant test. Besides non-pesticide materials, difenoconazole and carbendazim showed best satisfactory to control this disease. We also found that anthracnose isolates from mango, strawberry and pomelo, cannot cause anthracnose disease on the water caltops.
Subjects
Water caltrops
anthracnose
epidemiology
non-pesticide control
SDGs
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-105-R02633023-1.pdf
Size
23.54 KB
Format
Adobe PDF
Checksum
(MD5):c2ce7aa36a1f43b1b23e3a79ee2ed7c2