First report of alstroemeria wilt caused by Fusarium oxysporum in India 

V. Shanmugam*, S. Kumar, M.K. Singh, R. Verma, V. Sharma and N.S. Ajit 

Floriculture Division, Institute of Himalayan Bioresource Technology, Palampur-176061, Himachal Pradesh, India

*shanpatho@yahoo.com

Accepted for publication 25/10/06

Hybrids of Alstroemeria (Alstroemeriaceae), commonly called Peruvian Lily, are an exotic, rhizomatous and perennial cut flower crop widely cultivated under protection in India.  Nine hybrids (cvs. Alladin, Amor, Capri, Cinderella, Pluto, Rosita, Serena, Tiara and No. 14) were procured from three locations in India by the Institute of Himalayan Bioresource Technology (IHBT) in 2000-2001.  During cultivation, plants of all cultivars exhibited leaf chlorosis and slight vein clearing on outer leaflets, followed by leaf yellowing and abscission, discolouration of stem vascular tissue and death. 

Figure 1: Symptoms of alstroemeria wilt following artificial inoculation with Fusarium oxysporum

Fusarium oxysporum was consistently isolated when sections of discoloured stem vascular tissue were surface sterilised (2% sodium hypochlorite) and plated on potato dextrose agar (PDA) or carnation leaf agar.  Single-spore isolates were identified based on morphological characters (Nelson et al., 1983).  Conidiophores were unbranched or branched short monophialides.  Microconidia were abundant, generally single celled, oval to kidney shaped and produced only in false heads 5-12 x 3-3.5 µm.  Macroconidia were abundant, slightly sickle-shaped and thin-walled, with an attenuated apical cell and a foot-shaped basal cell 35.0-60.0 x 3.0-5.0 µm. Chlamydospores were single or in pairs and profusely distributed.  The presence of chlamydospores and microconidia borne in false heads on short monophialides distinguished the fungus from closely related Fusarium species.  The culture has been deposited in the Microbial Type Culture Collection (MTCC 7677) of the Institute of Microbial Technology, Chandigarh, India.  The identity of the culture was also established by PCR amplification and sequencing of the internal transcript spacer (ITS) region (White et al., 1990) (Acc. No. AM 261761).

Pathogenicity tests were done twice in a screen house on 8-week-old plants of cv. No. 14.  Wounded roots were submerged for 10 min in a conidial suspension (1 x 10⁶ conidia per mL in sterile tap water), while control plants were dipped in sterile tap water.  Seedlings were transplanted into pots and maintained in a polytunnel. Symptoms observed on inoculated plants were similar to those in commercial glasshouses, including leaf wilt (3 weeks after inoculation) (Fig. 1), chlorosis, necrosis and plant death.  The pathogen was re-isolated from the stems of affected inoculated plants to confirm Koch’s postulates.  The control plants did not exhibit symptoms.

Root rot complex of alstroemeria caused by F. oxysporum in association with Pythium irregulare and Rhizoctonia solani was earlier reported in Canada (Chang & Mirza, 1993) and Germany (Chang et al., 1994).  This is the first report of Fusarium oxysporum causing alstroemeria wilt in India.  

Acknowledgement

We thank the Director, IHBT (CSIR), Palampur for support and encouragement during the course of this investigation. IHBT Publication Number: 0641.

References 

Chang KF, Barr DJS, Hwang SF, Mirza M, 1994. Effect of interactions between Fusarium, Rhizoctonia and Pythium on root and rhizome rot of Alstroemeria. Zeitschrift-fur-Pflanzenkrankheiten-und-Pflanzenschutz 101, 46-466.

Chang KF, Mirza A, 1993. The occurrence of root rot disease complex of Alstroemeria in Alberta. Canadian Plant Disease Survey 73, 3-8.

Nelson PE, Toussoun TA, Marasas WFO, 1983. Fusarium Species: An illustrated Manual for Identification. Pennsylvania, PA, USA: Pennsylvania State University Press.

White TJ, Bruns TD, Lee S, Taylor J, 1990. Analysis of phylogenetic relationships by amplification and direct sequencing of ribosomal RNA genes. In: Gelfand DH, Sninsky JJ, White TJ, eds. PCR Protocols: a Guide to Methods and Applications. New York, USA: Academic Press, 315-322.

The British Society for Plant Pathology