STUDY ON MORPHOLOGY AND PHYSIOLOGY OF Cotletotrichum spp, COLLECTED FROM SELECTED FRUIT SEEDLINGS AND THEIR BIOASSAY AGAINST FUNGICIDES AND Trichoderma hanianum

Abstract

Fifty seven diseased (anthracnose) leaf samples of mango, guava, litchi, lemon and jamun from six nurseries of Dhaka namely Krishibid Upakaran Nursery, Kharnarbari Nursery, Nupur Nursery, Yamin Nursery, Tanjila Nursery and Poribesh Sohayok Nursery have been collected. A total of Eighteen isolates of Colletotrichum gloeosporioides and one isolate of Gloeosporium spp. were isolated and studied for morphological and physiological variability. Bioassay of the isolates was conducted against three fungicides and one bio controlling agent. Highest (17.6 um) and lowest (7.1 urn) length of conidia were observed for lemon (Oakjamil) and guava (Apel) isolates respectively where highest (4.S urn) and lowest (2 urn) breadth of conidia were observed for litchi (8ombai) and guava (Apel) isolates respectively. Effect of temperature on ,the mycelial growth of Colletotrichum spp. was studied at 18°C, 24°C, 2SoC and 32°C. The lowest mycelial growth was observed at 1SoC, then it increased at 24°C and the highest growth was observed at 28°C while the growth decreased at 32°C temperature. The highest and the lowest 56.66 mm and 14.16 mm mycelial growth were recorded at 2SoC and ISoC respectively after 7 days of incubation. Tolerance of 19 isolates of Colletotrichum spp. was tested against three fungicides, namely Bavistin 50 WP, Cupravit SO WP and Indofil M- 4S at the rate of SOO, 1000, 1500 and 2000 ug/rnl and was incubated for 7 days. Among the three fungicides Bavistin SOWP showed best performance in controlling Colletotrichum spp. isolates. Colletotrichum spp. isolates could not grow at all in 1500 ug/ml where Cupravit 50W? and Mancozeb SOWP stopped isolates growth at 2000 ug/rnl. Interaction study between CoJletotrichum spp. isolates and Trichoderma were done by using dual culture method. It was observed that in all the cases Trichoderma inhibited growth of Colletotrichum spp. after 7' days of incubation Trichoderma grew over Colletotrichum spp. after IS days and lysed zone was formed at the point of meeting. Trichoderma based bio fungicide could be an effective option to control Colletotrichum gloeosporioides.