|
KMID : 0903619720110010041
|
|
Journal of the Korean Society for Horticultural Science
1972 Volume.11 No. 1 p.41 ~ p.47
|
|
|
Studies on Causal Agents , Overwintering of Organisms and Control of Alternaria Leaf Spot of Apple
|
|
|
|
|
Abstract
|
|
|
An unknown disease of apple causing brown or blackish brown leaf spot has been observed through the main apple areas in Korea since 1966-´67. Some varieties of apple, such as Indo and Delicious group apples are especially susceptible to the disease. This study has been done to see the causal agent of disease, overwintering of organism and the establishment of controlling measure of the disease. The results obtained are summarized as follows.
1. Isolation of causal agents were made on diseased leaves collected from two apple growing area. As the result of the experiment, Alternaria was the most frequently obtained and isolation of Phyllosticta and Coniothyrium were next.
2. The necrotic leaf spot were produced by the artificial inoculation with conidial suspension of Alternaria isolates from the apple varieties Indo and Starking. But Alternaria isolates from Rolls, isolates of Phyllosticta and Conithyrium were not proved pathogenicity to the healthy leaves under the same conditions.
3. According to the laboratory experiments, Alternaria sp. lived overwinter in the diseased lesions of the overwintered fallen leaves and twigs which were infected severely in, the previous year. The fungi were also isolated from the winter bud.
4. According to in vito, the spore germination of Alternaria sp. was highly inhibited by Polvoxin and Difolatan. S-7258 was not effective to inhibition of spore germination, but it wvas reasonably effective to inhibition of mycelial growth and sporulation. The mycelial growth and the sporulation of Alternaria sp. is-ere also markedly inhibited by Polyoxin and Difolatan compared with others.
5. The effectiveness of fungicides was reduced gradually as the time after treatment increased. Difolatan retained approximately 80 percent of the original activity even after 15 days. Difolatan had the highest followed by Polyoxin, S-7258, and Monox in that order.
6. Under the conditions of artificial infection, Difolatan gave the best control of Alternaria leaf spot and followed by S-7258 and Polyoxin.
7. Correlation between the effectiveness of laboratory and pot test of several fungicides against Alternaria sp. which causes apple leaf spot was clearly associated except S-7258 in this experiment.
|
|
|
KEYWORD
|
|
|
|
|
|
FullTexts / Linksout information
|
|
|
|
|
|
Listed journal information
|
|
|
|
|