Anthracnose of lucky bamboo Dracaena sanderiana caused by the fungus Colletotrichum dracaenophilum in Egypt

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Dracaena sanderiana, of the family Liliaceae, is among the ornamental plants most frequently imported into Egypt. Typical anthracnose symptoms were observed on the stems of imported D. sanderiana samples. The pathogen was isolated, demonstrated to be pathogenic based on Koch’s rule and identified as Colletotrichum dracaenophilum. The optimum temperature for its growth ranges from 25 to 30 C, maintained for 8 days. Kemazed 50% wettable powder (WP) was the most effective fungicide against the pathogen, as no fungal growth was observed over 100 ppm. The biocontrol agents Trichoderma harzianum and Trichoderma viride followed by Bacillus subtilis and Bacillus pumilus caused the highest reduction in fungal growth. To the best of our knowledge, this report describes the first time that this pathogen was observed on D. sanderiana in Egypt. Journal of Advanced Research (2016) 7, 327–335 Cairo University Journal of Advanced Research ORIGINAL ARTICLE Anthracnose of lucky bamboo Dracaena sanderiana caused by the fungus Colletotrichum dracaenophilum in Egypt Ahmed A Morsy, Ibrahim E Elshahawy * Plant Pathology Department, Agricultural and Biological Research Division, National Research Centre, Giza, Egypt G R A P H I C A L A B S T R A C T A R T I C L E I N F O Article history: Received November 2015 Received in revised form 21 January 2016 Accepted 22 January 2016 Available online 16 February 2016 A B S T R A C T Dracaena sanderiana, of the family Liliaceae, is among the ornamental plants most frequently imported into Egypt Typical anthracnose symptoms were observed on the stems of imported D sanderiana samples The pathogen was isolated, demonstrated to be pathogenic based on Koch’s rule and identified as Colletotrichum dracaenophilum The optimum temperature for its growth ranges from 25 to 30 °C, maintained for days Kemazed 50% wettable powder (WP) was the most effective fungicide against the pathogen, as no fungal growth was observed * Corresponding author Tel.: +20 1279180670; fax: +20 57 2403868 E-mail address: ibrahim_nrc@yahoo.com (I.E Elshahawy) Peer review under responsibility of Cairo University Production and hosting by Elsevier http://dx.doi.org/10.1016/j.jare.2016.01.002 2090-1232 Ó 2016 Production and hosting by Elsevier B.V on behalf of Cairo University 328 Keywords: Anthracnose Dracaena sanderiana Colletotrichum dracaenophilum Lucky bamboo A.A Morsy and I.E Elshahawy over 100 ppm The biocontrol agents Trichoderma harzianum and Trichoderma viride followed by Bacillus subtilis and Bacillus pumilus caused the highest reduction in fungal growth To the best of our knowledge, this report describes the first time that this pathogen was observed on D sanderiana in Egypt Ó 2016 Production and hosting by Elsevier B.V on behalf of Cairo University Introduction Pathogenicity tests Lucky bamboo (Dracaena sanderiana hort ex Mast.) is among the ornamental plants most frequently imported into Egypt This bamboo is also known as Dracaena braunii [1] Although the word bamboo occurs in several of its common names, D sanderiana is actually of an entirely different taxonomic order from true bamboos In Egypt, lucky bamboo is the most popular indoor plant and is frequently imported and resold in attractive pots Colletotrichum spp is an imperfect fungus belonging to the Melanconiales Members of the genus Colletotrichum cause diseases on a number of host plants These diseases, often referred to as anthracnose, include strawberry black spot and key lime anthracnose (caused by Colletotrichum acutatum), tomato fruit anthracnose (caused by Colletotrichum coccodes), red sorghum stalk rot (caused by Colletotrichum graminicola), coffee berry disease (caused by Colletotrichum kawahae), bean anthracnose (caused by Colletotrichum lindemuthianum) and many others [2] Additional species of Colletotrichum with conidia greater than 20 lm have been encountered on living plants of D sanderiana (lucky bamboo) from China [3] In Bulgaria and Iran, Bobev et al [4] and Komaki et al [5], respectively, provided the first reports that Colletotrichum dracaenophilum infects the stems of potted D sanderiana plants, causing anthracnose disease In the United States, Sharma et al [6] isolated, characterized and tested fungicide treatments to control Colletotrichum spp causing anthracnose on lucky bamboo, D sanderiana They also reported that C dracaenophilum caused the most severe disease on lucky bamboo, whereas one isolate of the Colletotrichum gloeosporioides species complex was less pathogenic to all Dracaena spp and varieties tested In Egypt, during March 2015, anthracnose symptoms were recorded on D sanderiana plants Therefore, the objectives of this work were (i) to describe the symptoms of lucky bamboo anthracnose, (ii) to isolate, identify and test the pathogenicity of the causal agent, (iii) to determine the effect of temperature on the growth of the causal pathogen and (iv) to evaluate the effect of certain fungicides and biocontrol agents on the growth of the pathogen Pathogenicity was confirmed by fulfilling Koch’s postulates on rooted cuttings of lucky bamboo plants as well as detached stem segments, according to Bobev et al [4] Twenty cuttings of lucky bamboo plants were surface disinfected with 1.5% sodium hypochlorite (NaOCl) for min, followed by several rinses with sterile distilled water before being sown in five glass bottles containing 500 mL sterile water Thirty days later, these bamboo plants were divided into two sets The stems of the first set were wounded (ten wounds per plant) using a sterile needle at cm intervals The stems of plants of the first set were inoculated by inserting small mycelial plugs from 10day-old potato dextrose agar (PDA) cultures of C dracaenophilum into wounds, which were subsequently covered with Parafilm strips Pure agar plugs were used to inoculate the wounded stems of the control plants (5 plants) Both inoculated and control plants were kept at 28 ± °C Anthracnose symptoms were observed visually for sixty days after inoculation The stems of the second set (5 plants) were injected with 0.5 mL plantÀ1 of C dracaenophilum conidial suspension (2 Â 106 conidia mLÀ1) using a sterilized syringe [9] The injected and un-injected (5 plants) stems of lucky bamboo plants were covered with plastic polyethylene bags for 24 h to provide humid conditions Anthracnose symptoms were observed visually In addition, the stems of apparently healthy lucky bamboo plants were cut longitudinally and horizontally into 1–3 cm segments These segments were inoculated with one drop of C dracaenophilum conidial suspension (2 Â 106 conidia mLÀ1) after surface disinfection Five stem segments from each type of longitudinal and horizontal pieces were used as replicates, and the experiment was replicated twice The rot of the detached stem segments was observed visually Material and methods Isolation and identification of the causal pathogen In March 2015, disease problems on the stems of imported (Netherlands) indoor lucky bamboo plants (D sanderiana) were observed The symptoms were observed during several months after the consumer purchased them from the retail stores located in Giza governorate More than 50 diseased samples with typical anthracnose symptoms were collected to isolate the pathogen based on Koch’s rule [7] The obtained fungal colonies were identified according to the Colletotrichum description reported by Sutton [8] and according to Farr et al [3] Effect of temperature on the growth of C dracaenophilum Fresh potato dextrose agar (PDA) plates were inoculated with a mm mycelial disk cut with a sterile cork borer from the margin of a 10-days-old colony of C dracaenophilum Plates were incubated in an incubator at 5, 10, 15, 20, 25, 30, 35 and 40 °C The radial growth of C dracaenophilum was measured in two perpendicular directions at 4, 8, 10 and 14 days after inoculation Four Petri plates were used as replicates for each combination of temperature and incubation period Inhibitor effect of fungicides on the growth of C dracaenophilum The inhibition effects of ten different fungicides under different concentrations viz., 0, 25, 50, 100, 200, 300, 400, 500 and 600 ppm against the pathogen were determined The systemic fungicides were dimethomorph 6% + copper oxychloride 40% (Acrobat Copper 46%), carbendazim (Kemazed 50% Anthracnose of lucky bamboo Dracaena sanderiana in Egypt Table 329 Analysis of variance for RCBD SOV Replication A (temperature T or fungicide F) B (incubation period I or concentration C) AB Error Total Table Table df P-values df P-values (r À 1) = AÀ1=7 BÀ1=3 (A À 1) (B À 1) = 21 (AB À 1) (r À 1) = 93 (ABr À 1) = 127 0.48
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