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Anthracnose and Leaf Spot Diseases of Aloe Vera L.from Bangladesh.

ANITA RANI SHUTRODHAR
Department of Botany, University of Dhaka, Dhaka-1000, Bangladesh.

SHAMIM SHAMSI
Department of Botany, University of Dhaka, Dhaka-1000, Bangladesh.

Abstract/ Executive Summary:

Characteristic symptoms of anthracnose and leaf spot were recorded from diseased leaf samples of Aloe vera L. A total of 8 fungal species, namely Alternaria plurise ptata (Karst. & Har.) Jorstad, Aspergillus flavus Link, Aspergillus niger Van Tieghem, Cladosporium oxysporum Berk. & Curt., Col/etotrichum gloeosporioides (Penz.) Sacc., Nigrospora oryzae (Berk. & Br.) Petch, Penicillium sp. and Pestalotiopsis guepinii (Desm.) Stay. were found to be associated with healthy and diseased leaf samples. In addition to above 8 fungi, Curvu/aria brachyospora Boedijn, Epicoccum purpurascens Ehrenb. ex Schlecht and Sclerotium sp. were also associated with diseased leaf samples of the plant. The prevalence of the fungi ranged 1.43 - 13.35% on healthy leaves and 1.43 - 62.16% on infected leaves. The frequency of C. gloeosporioides was the maximum and that of Aspergillus and Penicillium was the lowest. Pathogenicity test revealed that C. gloeosporioides causes anthracnose and E. purpurascens and P. guepinii cause leaf spots of A. vera.

Keywords: Anthracnose, Leaf spot diseases, Aloe vera

Location: Healthy samples of Aloe vera were collected from Farmgate, Gulshan, Mirpur, Mohakhali and Botanic Garden of Dhaka University Campus

Start Date: 00-02-2010

End Date: 00-04-2011

Program Area: Pest Management

Commodity: Aloe Vera

Objectives:

To identify diseases of Aloe plant with their causal agents occur in Bangladesh. .

Methodology:

A total of 30 diseased and healthy samples of Aloe vera were collected from Farmgate, Gulshan, Mirpur, Mohakhali and Botanic Garden of Dhaka University Campus during February, 2010 to April, 2011. Symptoms of the disease were recorded. The fungi associated with the healthy as well as infected leaf samples were isolated on potato dextrose agar (PDA) medium following tissue planting method. The leaf samples were cut into small pieces (2² mm) with a sterilized scalpel from each sample. The inocula were surface sterilized by dipping in 10% Clorox for 3 minutes and rinsed in sterilized distilled water for 3 times. The surface sterilized inocula were placed in Petri plates containing sterilized PDA medium, with 3 inocula per plate and incubated for 5 - 7 days at 25 ± 211C. The fungi isolated from the inocula were identified based on their morphological characteristics using appropriate key books(^8-12) Identified fungi were purified and their pathogenicity was examined by inoculating fresh healthy leaves of Aloe plant. Healthy seedling of Aloe plant was transplanted in pots (30 cm diam) containing sterilized soil with three seedlings per pot and allowed to grow for one month in net house provided necessary water and nutrients . Healthy leaves of the seedlings were washed with sterilized distilled water and then surface sterilized with 10% Chlorox and again washed with sterilized distilled water . Pricked and unpicked leaves were inoculated. Surface sterilized leaves were pricked with sterilized needle. For inoculation 5 mm (diam) mycelial block cut from young PDA culture of each test fungus were placed on both pricked and unpricked leaves and wrapped with surface sterilized polythene paper. Leaves under control received only fresh PDA block without fungal inoculum . Three leaves were inoculated for each treatment and for each fungus. The inoculated plants were placed in a clean bench following completely randomized design. The plants were examined daily and continued for 10 days to record the development of symptoms. Symptom produced on artificial inoculated leaves were recorded and compared with those observed on naturally inoculated leaves. The fungi were reisolated from the inoculated leaves of A. vera on PDA mediu m to ful fi l l Koch's postul ates. Al l diseased speci mens and associated causal fungi were preserved in the Herbarium, Myology and Plant Pathology Division, Department of Botan y, Uni versity of Dha ka, Bangladesh .

Source of Information: Dhaka Univ . J. Biol. Sci. 22(2): 103-108, 2013 (July)

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

Aloe plants were found to be infected with severe leaf spot and anthracnose symptoms under natural and inoculated conditions. The symptoms appeared on the leaves, as dark brown spots and the leaves become dried . Spots were subcircular 2 - 6 mm in diameter. In severe case infection started from the leaf edge and the affected leaves shrinked and dried from the tip. A total of 11 species of fungi were isolated and they were associated with diseased samples. Curvularia brachyos pora, E . pur pura scens and Sclerotium sp. were not associated with healthy leaf samples. The prevalence of the fungi ranged 1.43 - 13.35% on healthy leaves and 1.43 - 62.16% on infected leaves. In case of infected leaves, the frequency of Colletotrichum gloeosporioide was the maximum and tha t of Aspergillus niger and Penicillium sp. was the mini mum . In India Colletotrichum gloeosporioide, Fusarium solani (Mart.) Sacc., Peslalotiop s is versicolor (Speg.) Stay., Phoma sorghina (Sacc.) Boerma, Dovenbosch & Vankest and Uromyces aloes (Cks.) P. Magn have been recorded from infected l eaves of Aloe species (¹³⁾The results of pathogenicity test revealed that C. g loeosporioides, E. purpurascens and P. guepinii were capable of causing characteristic symptoms on inoculated leaves The disease symptoms produced by the fungi were similar to those which were observed i n naturally infected plants. Plants inoculated with pure PDA (control) and without prickin g did not produce any symptom. It indicates that the test fungi C. gloeosporioides, E. pur pura scens and P. guepinii were capable of causing infection on pricked leaves only. The inoculated fungi were also re-isolated from the symptoms successf ully . The finding reveals that A. pluriseptata, A. flavus, A. niger, C. oxysporu m., C. g loeosporioide, C. brachyospora, E. pur pura scens, N. oryzae, Penicillium sp. and P. guepinii. and Sclerotiu m sp. are associated ted wi th Aloe vera leaves. Among them E. purpurascens and P . guepinii are responsible for leaf spots and C. gloeosporioide caused anthracnose of A. vera plant. This is the first report on pathogenic potentiality of E. purpuras cens and P. guepinii on the plant. At the same time this is the first report of diseases of Aloe vera and its causal agents from Bangladesh.

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