Antifungal activity of Thuja orientalis against transmittedseed-borne Alternaria zinniae, causing leaf spot disease in zinnia (Zinnia elegans L.)

• Published in: Australasian plant pathology Vol. 48; no. 6; pp. 583 - 594
• Main Authors: Moharam, Moustafa H. A., Soliman, Yasin M. Y.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-11-2019; Springer Nature B.V
• Subjects: Agriculture; Alternaria; Antifungal activity; Biomedical and Life Sciences; Ecology; Embryos; Entomology; Field tests; Fungicides; Germination; Leaf area; Leafspot; Life Sciences; Methanol; Mycelia; Original Paper; Plant extracts; Plant Pathology; Plant Sciences; Plants; Seedlings; Seeds; Spore germination; Water treatment; Zinnia; Seed transmission; Control; Extract
• ISSN: 0815-3191; 1448-6032
• DOI: 10.1007/s13313-019-00661-z

In this study, four species of
Alternaria
as
A. alternata
(Fr.) Keissler,
A. solani
(Sorauer),
A. tenuissima
(Kunze) Wiltshire and
A
.
zinniae
M.B. Ellis were detected in seed samples of zinnia collected from the commercial lots in Egypt. Koch’s postulates performed in pots under greenhouse conditions proved that only
A
.
zinniae
was the main causal pathogen of leaf spot. Moreover, it was frequently detected in all seed components of coat, cotyledon, and embryo. Disease severity induced by all isolates of
A
.
zinniae
was highly related to growth stages of zinnia, where it increased with the development of plant age from 1 to 8 weeks old. Transmission of
A
.
zinniae
infected seed to seedling was at 51.3% (blotter method), whereas using seedling symptom test and test tube agar method exhibited infected seedling of 58.5 and 55.8%, respectively. In the efficacy test of extracts from different materials of thuja against
A
.
zinniae
performed in vitro, leaf methanol and water extracts were the most effective treatments, where they completely inhibited spore germination at a concentration of (5 and 3%, respectively) and mycelial growth at (7 and 7%, respectively) followed by seed methanol and water extracts. In the field experiments conducted during 2016 and 2017, a highly significant reduction in the percent of leaf area infected with
A. zinniae
of zinnia occurred after seeds were treated by soaking in methanol extracts of 3% leaf and 7% seed for 15 min before sowing. Hence, there is a scope to integrate thuja leaf and seed extracts as plant-derived agents for eco-friendly management of
A
.
zinniae
on zinnia.