Vettraino A M, Shrestha G P, Vannini A
Department of Plant Protection-University of Tuscia, Via S. Camillo de Lellis 01100 Viterbo, Italy.
Fruit Development Directorate, Kirtipur, Kathmandu, Nepal.
Plant Dis. 2009 Feb;93(2):200. doi: 10.1094/PDIS-93-2-0200A.
Leaf drop, wilt, and mortality were observed in September of 2007 on approximately 10% of 1- to 2-year-old olive (Olea europaea cv. Leccino) plants shipped from Europe and growing in a nursery in the District of Makwampur, Nepal. Roots of symptomatic and asymptomatic plants were disinfected in 1% NaOCl, cut into 1 cm long pieces, plated on 2% potato dextrose agar, and maintained at 20°C with 14 h of light per day. Colonies with white mycelium developed after 3 days. Microconidia and three-septated macroconidia averaged 11 × 3.9 μm and 38 × 5 μm, respectively. Chlamydospores were produced singly and in pairs. On the basis of culture characteristics, the fungus was identified as Fusarium solani (2). The ITS1-5.8S-ITS2 DNA sequences of 10 monoconidial cultures shared 99% identity with F. solani strains available on the NCBI databases (GenBank Accession Nos. 1115947 and 1115999). Pathogenicity tests were conducted with F. solani isolates NR1 and NR2 obtained from symptomatic plants. Twelve-month-old rooted cuttings of O. europaea cv. Leccino were transferred to pots containing a soilless mix and F. solani-infected oat grains (10:1 vol/vol). Fifteen plants of each F. solani isolate were inoculated. Noninfested sterilized oat grains were used for the control treatment. Symptoms on inoculated plants included leaf abscission followed by wilting and plant death approximately 10 days after inoculation and resembled those observed on the naturally infected plants. Noninoculated control plants remained healthy. The fungus was reisolated from roots of symptomatic tissues and was identical in appearance to the isolates used to inoculate the plants. No colonies of F. solani were isolated from noninoculated plants. F. solani has been reported as weakly pathogenic on olive in Spain (4) and highly aggressive on olive in Argentina (1) and India (3). To our knowledge, this is the first report of F. solani causing wilt and mortality of young olive plants in Nepal. References: (1) S. Babbit et al. Plant Dis. 86:326, 2002. (2) C. Booth. Fusarium Laboratory Guide to the Identification of the Major Species. CMI, Kew, England, 1977. (3) R. L. Munjal et al. Studies on diseases of olive in Himachal Pradesh. Page 437 in: Improvement of Forest Biomass. Symposium Proceedings. Indian Society of Tree Scientists. P. K. Kosla, ed. Sdan, India, 1982. (4) M. E. Sánchez Hernández et al. Eur. J. Plant Pathol. 104:347, 1998.
2007年9月，在从欧洲运来并种植于尼泊尔马克万布尔区一家苗圃中的约10%的1至2年生油橄榄（油橄榄品种莱基诺）植株上，观察到落叶、枯萎和死亡现象。将有症状和无症状植株的根系在1%次氯酸钠中消毒，切成1厘米长的小段，接种到2%马铃薯葡萄糖琼脂培养基上，置于20°C、每天光照14小时的条件下培养。3天后长出了带有白色菌丝体的菌落。小型分生孢子和具3个隔膜的大型分生孢子平均大小分别为11×3.9微米和38×5微米。厚垣孢子单个或成对产生。根据培养特征，该真菌被鉴定为茄形镰刀菌（2）。10个单孢培养物的ITS1-5.8S-ITS2 DNA序列与NCBI数据库中（GenBank登录号1115947和1115999）的茄形镰刀菌菌株有99%的同源性。用从有症状植株上分离得到的茄形镰刀菌分离物NR1和NR2进行致病性测试。将12月龄的油橄榄品种莱基诺扦插生根苗转移到装有无土基质和被茄形镰刀菌感染的燕麦粒（体积比10:1）的花盆中。每个茄形镰刀菌分离物接种15株植株。未受侵染的灭菌燕麦粒用于对照处理。接种植株上出现的症状包括接种后约10天叶片脱落，随后枯萎并植株死亡，与在自然感染植株上观察到的症状相似。未接种的对照植株保持健康。从有症状组织的根部重新分离出该真菌，其外观与用于接种植株的分离物相同。未从未接种植株上分离到茄形镰刀菌菌落。据报道，茄形镰刀菌在西班牙对油橄榄致病性较弱（4），在阿根廷（1）和印度（3）对油橄榄具有高度侵袭性。据我们所知，这是关于茄形镰刀菌导致尼泊尔幼龄油橄榄植株枯萎和死亡的首次报道。参考文献：（1）S. Babbit等人，《植物病害》86:326，2002年。（2）C. Booth，《镰刀菌主要种类鉴定实验室指南》，CMI，英国基尤，1977年。（3）R. L. Munjal等人，《喜马偕尔邦油橄榄病害研究》，载于《森林生物量改良》，研讨会论文集，印度树木科学家协会，P. K. Kosla主编，印度斯丹，1982年，第437页。（4）M. E. Sánchez Hernández等人，《欧洲植物病理学杂志》104:347，1998年。
