Etiology and control of anthurium flower rot

• Main Authors: Wu San Zu, 吳珊如
• Other Authors: Ho Wang Ching
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/52969646997008579795

碩士 === 國立屏東科技大學 === 植物保護系 === 93 === Recently, the symptoms of flower rot, spathe petiole canker, leaf spot and root rot of Anthurium ‘Nitta Orange’ were found in two anthurium commercial nurseries at Shinpi and Chaochou of Pingtung county in southern Taiwan. Seven isolates of Corynespora sp. obtained from disease portions caused the typical flower rot symptoms on detached anthurium spathes. None of the control spathes developed disease symptoms. Corynespora sp. was reisolated from the inoculated tissues, fulfilling the Koch’s postulates. AC-7 was found to be the most virulent isolate, when the detached spathes were inoculated with spore suspensions of seven anthurium isolates. Colonies were pale brown on 10%VA and dark-green on PDA. Conidiophores were erect and simple, straight or slightly curved, unbranched, pale to mid brown. Conidiophores formed on host tissues often with a bulbous base, 67.2-267.9 × 4.1-7.9 μm (mean 133.3±38.0 × 5.5±0.8 μm). Conidiophores of AC-7 formed on PDA were 23.5-199.6 × 3.5-8.8 μm (mean 80.9±32.7 × 5.2±0.9 μm). Conidia were borne singly or in chains at the apex of conidiophores, hyaline brown, straight or slightly curved, obclavate to cylindrical. Conidia formed on host tissues were 14.2-261.1 × 4.7-11.6 μm (mean 73.0±44.7 × 7.8±1.3 μm), with 0-17 pseudosepta. Conidia of AC-7 formed on PDA were 12.3-196.1 × 4.1-12.7 μm (mean 51.0±29.8 × 7.8±1.5 μm), with 0-13 pseudosepta. Conidiophores and conidia of AC-3 are similar to those of AC-7 in size. The fungus was identified as Corynespora cassiicola (Berk.＆Curt.) Wei according to the references of Wei(1950) and Ellis(1957). The disease on anthurium spathes caused by C. cassiicola was named as anthurium flower rot. This new disease on anthurium has not been reported previously in the world. The optimum temperature for spore germination and mycelial linear growth of C. cassiicola isolates AC-3 and AC-7 was 28℃. Among 10%VA, PSA and PDA, the best medium for mycelial linear growth and spore production of C. cassiicola isolates AC-3 and AC-7 was PDA. Spore germination of C. cassiicola occurred under high humidity, and spore germination rate was 98% in the water. The optimum pH value for spore germination and mycelial linear growth of C. cassiicola was 5-11. Disease incidence of anthurium flower rot was higher on wounded sapthes than unwounded spathes. The optimum temperature for development of anthurium flower rot was 28℃. The minimum concentration of spore for infection was 103 spores/ml. In cross inoculation trials with isolates from anthurium, cucumber and tomato, AC-7 isolate from Anthurium, and Cory-13 and Cory-18 isolates from tomato were pathogenic on cucumber, tomato and anthurium, but CC-2 isolate from cucumber was pathogenic on cucumber and tomato, but not anthurium. C. cassiicola AC-7 was pathogenic on eggplant, hot pepper, sweet pepper, tobacco, soybean, asparagus bean, papaya, watermelon, mint, arrowhead vine, African violet, poinsettia, and zebra plant, but caused no symptoms on arrowroot, aglaonema, rubber plant, lipstick vine, and azalea. In diseases resistant screening tests among anthurium cuttings cultivars, 10, M22, M01, ‘Anuenue’, ‘Rosa’, ‘Vanilla’, and ‘Pistache’ were immune to anthurium flower rot caused by C. cassiicola, while ‘Nitta Orange’, ‘Mini Obake’ and LOB1 were highly susceptible, M01、M02、M03、M06、M12、M15、H5-4 were immune to anthurium seedling damping-off caused by C. cassiicola, while ‘Mini Obake’, LOB1 and M23 were highly susceptible. Among the 18 fungicides tested, benomyl, thiabendazole＋oxine-copper and propineb＋thiophanatemethyl were most effective in suppressing spore germination and mycelial linear growth of AC-7. Detached spathe tests showed that all eight fungicides were excellent in protection against anthurium flower rot, and that benomyl 1500X, propineb＋thiophanatemethyl 500X and 1500X had better curative effect than other fungicides. The dual culture test showed that T1, T7 and T14 of Trichoderma spp. could inhibit the growth rate of AC-7 more than 60% and that they could grow over the AC-7 colony. Antibiotic activity tests with the cellophane method showed that T8 has better ability to produce antibiotics than other Trichoderma isolates. The T7 showed better protection effect on detached spathe tests. Trichoderma isolates T1, T7 and T8, Bacillus subtilis (Tai-yen) and Streptomyces sp. (Tai yen) did not have curative effect against anthurium flower rot.