First Report of Colletotrichum dematium on Tomato in Argentina

Abstract

Anthracnose of tomato (Lycopersicon esculentum Mill. var. pyriforme (Dunal) L.H. Bailey) was observed on ripe fruits of pear-shaped tomato in the postharvest phase during September 1998 to February 1999. Anthracnose causes a rot of ripe fruit that can cause significant losses in the field and during storage. Symptoms occurred on fruits of several cultivars grown in commercial fields at La Plata, Buenos Aires Province, Argentina. Fruit rot began as small, round (1 to 2 mm diameter), grayish, sunken, watersoaked lesions. The center of the spots became tan and flecked with small black specks. Individual spots enlarged concentrically to approximately 2 cm in diameter and became covered with numerous, submerged, black acervuli that formed in concentric rings and, under wet conditions, produced a mass of slimy salmon-colored spores. In time, total fruit rot often occurred due to coalescence of multiple lesions. Symptoms developed during storage, resulting in diminished fruit quality and marketable value. Colletotrichum dematium (Pers.) Grove was isolated consistently by plating surface-disinfected lesion margins on acidified potato dextrose agar (PDA). Colonies on PDA were gray, olivaceous to black, with abundant acervuli. Conidia were one-celled, hyaline, and falcate, with acute apices measuring 17 to 28 × 2 to 4 μm, consistent with the description of C. dematium (1). Acervuli were superficial, black, and setose. A fungal isolate was selected to complete Koch's postulates. Surface-disinfected ripe fruits of tomato cvs. Perita and Larga Vida were punctured with a sterile needle containing conidia from sporulating cultures. Inoculated fruits were incubated at 25°C for 48 h in a moist chamber. After 3 to 5 days, soft, watery spots developed at the inoculation point on the fruit, and C. dematium was reisolated from the lesions. Fruits that were punctured but not inoculated did not develop symptoms or yield C. dematium. To confirm pathogenicity on leaves, disease-free tomato plants were sprayed with a conidial suspension (2 × 105 spores per ml) of the pathogen. Control plants were sprayed with sterile water. Inoculated plants and controls were left bagged for 48 h and placed in a greenhouse at 20 to 25°C. After 1 week, necrotic leaf spots developed on inoculated plants. Leaf spots were small, circular, and brown. Yellow rings often surrounded the spots. C. dematium was reisolated from lesions on these leaves. This is the first report of C. dematium on tomato in Argentina. Reference: (1) B. C. Sutton. 1980. The Coelomycetes: Fungi Imperfecti with Pycnidia, Acervuli and Stromata. Commonwealth Mycological Institute, Kew, England.

Single‐marker and haplotype‐based association analysis of anthracnose (Colletotrichum dematium)resistance in spinach (Spinacia oleracea)

“…Colletotrichum siamense has been found on partridge tea, citrus and mango in China, India, South Africa and Brazil (Cheng et al, ; Liu et al, ; Liu, Chen, Liu, & Hou, ). Similarly, C. dematium has been isolated from a range of crops including common knotgrass in China, cowpea in South Africa, tomato fruits and mulberry in Argentina, the ornamental plant German Statice in Bulgaria, and spinach in Australia and the USA (Correll et al, ; Smith & Aveling, ; Yoshida & Shirata, ; Dal Bello, ; Washington et al, ; Bobev, Jelev, Zveibil, Maymon, & Freeman, ; Liu, Jin, et al, ). These studies illustrate that different species and strains of Colletotrichum may thrive in the same environment on the same host plant, on different host plant species, or in the case of C. dematium , on different host plants in a wide range of environments.…”