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Die-back of Jackfruit: Its Cause and Control

G. M. Mujibar Rahamn
Professor
Department of Agro forestry, BAU, Mymensingh.

M. M. U. Akanda
Graduate Student
Department of Agro forestry, BAU, Mymensingh.

Abstract/ Executive Summary:

The cause of die-back and its control was investigated in the Department of Agroforestry, Bangladesh Agricultural University, Mymensingh during February to October, 1998. The causes of die-back of Jackfruit were identified as Botryodiplodia theobromae and Colletotrichum gloeosporioides. Proof of pathogenicity and symptoms produced by these two pathogens were studied in detail. The symptoms of die-back first appear at the tip of small twigs as a minute dark color lesion which progress downwards following a change in color of the surrounding leaves from dark green to pale green, sometimes light yellow and finally become reddish. The infection of the disease appeared in the tips gradually extending back with drying of the affected twigs having a distinct demarcation from the healthy area. At that time the leaves start to fall off. The infections extended on small branches and gradually on the major branches and sometimes the most part of the crown were found die-backed. The affected twigs and branches which were dying back turned grayish white developing some black dot like structures caused by B. theobromae; while the twigs/branches turned into grayish black without developing any dot like structure as is caused by C. gloeosporioides. As regard control, in vitro screening of fungicides revealed that Topsin M, Rovral 70 WP and Ridomil MZ were highly effective in inhibiting the mycelial growth of the causal fungi. Application of these fungicides in the pruned twigs of jackfruit in situ gave reduction of disease development. Use of balanced fertilizers (urea 1 Kg, TSP 0.8 kg and MP 1 kg/tree) followed by chopped eucalyptus leaves (2.5 kg/tree) and cowdung (80 kg/tree) immediately after harvesting season in the die-back affected trees improved the general health condition of the affected tree. Therefore, integrated approaches incorporating cultural and chemical treatments are suggested for die-back control in Jackfruit.

Keywords: Jackfruit, Diseases, Cause, Control

Location: Department of Agroforestry, Bangladesh Agricultural University, Mymensingh

Start Date: 00-02-1998

End Date: 00-10-1998

Program Area: Pest Management

Commodity: Diseases

Objectives:

1. To identify the cause(s) of the fungal origin

2. To develop its control measures.

Methodology:

The symptoms of the disease were studied on the infected twigs or branches in situ in the field as well as on collected samples. Diseased twigs were used for isolation of the pathogen(s). Sterile blotting papers soaked in sterile water were placed thrice in the petridishes. Inocula were prepared from the junction of disease and healthy portion of collected sample (1 cm X 5 mm) and placed in moist blotter. The petridishes were then kept for incubation at room temperature (28±2^oC) for the growth and sporulation of the fungus. The fungi which sporulated in blotter were identified with help of light microscope and photographs were taken. Stem pieces (bark and wood), 5 mm in length, was cut from infected twigs for isolation. The inocula were surface sterilized with mercuric chloride (1:1000) solution for 1 minute and washed thrice in running water. Inocula were placed on acidified PDA plates aseptically. The plates were then incubated at 28±2^oC for several days and examined daily for any fungal growth. The fungi were transferred to fresh culture plates from where subculture was made into PDA plates by transferring single hyphal tip. The fungi were identified by observing colony character, linear growth, color and sporulation. Two years old seedlings of jackfruit were collected from Horticulture Centre, Mymensingh for pathogenicity test. The seedlings were planted in 10 inch diameter earthen pots. The seedlings were kept 48 hour covered with moist polythene. The test was conducted in glass house of Bangladesh Agricultural University, Mymensingh. Healthy twigs were inoculated with 5 mm fungal blocks of 5 days old culture of two isolated fungi viz. Botryodiplodia theobromae and Colltotrichum gloeosporioides. Inoculations were done with or without injury. The inoculated seedlings were kept 48 hours covered with moist polythene sheet. Control was maintained by following same procedure of inoculation but no inocula were used. Both the inoculated and controlled pots were watered properly and observed for symptom development up to 75 days of inoculation. After symptom development, the organisms were reisolated. Comparative efficacies of seven fungicides viz. Cupravit, Bavistin, Rovral 70 WP, Dithane M-45, Thiovit, Topsin M and Ridomil MZ against die-back pathogens were determined in the laboratory. It was done following the poisoned food technique with slight modifications. The suspensions of fungicides were made on the basis of active ingredient of each of the fungicide. Mycelial blocks of 5 mm diameter from 7 days old culture of the fungus were aseptically placed at the centre of the each petridish in an inverted position so that the fungus remain in direct contact with the medium poisoned with chemicals. Prior to this, the fungicides in different concentrations were incorporated in warm PDA medium. The mixed media were shaken well to give uniform dispersal of test chemicals. Three replications for each dose of the fungicides were maintained along with a control in which no chemical was added. The plates were incubated at room temperature. Linear growth of the fungus was measured 24 hour interval up to 3 day. In this experiment 6 fungicides viz. Ridomil MZ, Rovral 70 WP, Topsin M, Cupravit, Thiovit and Bavistin were included based on their performance in inhibiting the mycelia growth in laboratory test. For this purpose three moderately affected trees were selected in the BAU campus. In each tree, the die-back affected twigs were grouped into three categories having 3, 7 and 10 cm in diameter. All the twigs were cut off just below the junction of die- back affected and healthy area and were mounted with the paste of each of the selected fungicides in 3 replications. The paste of the test fungicides was made by mixing 1 g fungicide in 100 g flour i.e. 1: 100 concentrations. After mounting the paste, the cut surfaces of the treated twigs were covered with polythene. In case of controls paste without adding any fungicides were used followed by polythene covering. Data on the progress of die-back development were recorded after one month. Twelve moderately affected jackfruit trees were selected at BAU campus, Mymensingh to find out the effect of different management practices on the severity of disease. Out of twelve trees, three were managed with cowdung, three with balanced fertilizer, three with chopped Eucalyptus leaves and rest three were kept as control. In case of each treatment, the basal areas having 1.5-2 m diameter around each selected tree was spaded properly at the end of harvesting jackfruit (June, 1998). Cowdung was added at the rate of 80 kg/tree. In case of balanced fertilizers, Urea, TSP and MP was added at the rate of 1 kg, 0.8 kg and 1 kg/tree, respectively; while chopped eucalyptus leaves were applied @ 2.5 kg/tree. In case of control only soil was spaded. Observations on the condition of the treated plants were made after 5 months.

Source of Information: Proceedings of The National Workshop on Jackfruits Problem, Prospects, Research Activities and Development in Bangladesh, March 2011. Forestry Unit, Natural Resources Management Division, Bangladesh Agricultural Research Council, Dhaka-1215, Bangladesh. pp: 59-64.

Article Link (Online Journal):

Funding Source:

1.

Budget:

Total Budget (Tk.) :

Achievement/Findings:

Die-back of jackfruit caused by Colletotrichum gIoeosporioides was identified as a new pathogen in addition to previously reported fungus Botryodiplodia theobromae in Bangladesh. Integrated approaches incorporating cultural and chemical treatments are suggested for die-back control in Jack fruit.

Knowledge Management: Report/Proceedings