COMPATIBILITY OF AN ISOLATE OF TRICHODERMA HARZIANUM WITH FUNGICIDES AND ORGANIC AMENDMENTS
Tanbir Rubayet and M. K. A. Bhuiyan. 2012. Compatibility of an Isolate of Trichoderma harzianum with fungicides and organic amendments. Bangladesh J. Plant Pathol. 28 (1&2): 63-66.
An in-vitro study was undertaken to determine the effect of three fungicides namely Provax-200 (Carboxin), Rovral 50 WP (Iprodione) and Bavistin 50 WP (Carbendazim), and four organic materials namely mustrard oilcake, heat meal, chickpea meal, rice bran and tea waste on mycelium growth and sporulation of an isolate of Trichderma harzianum (T-10) following "poison food technique". The fungicides were used at 50, 100, 250 and 500 ppm concentrations. At different concentrations, inhibition in colony diameter ranged 2.22-18.89%, 7.78-22.22% and 90.00-100.00% under Provax-200, Rovral 50 WP and Bavistin 50 WP, respectively. The inhibition in sporulation was 4.52-11.76, 10.07-21.04% and 90.50-100.00%, respectively. At the concention of 10, 20 and 30%, inhibition of mycelium diameter due to amendment of PDA with mustard oilcake, tea waste, rice bran, chickpea meal and wheat meal ranged 0.00-36.30, 2.22-54.07 and 6.30-72.96%, respectively. Similarly inhibition of sporulation of T. hazianum at different concentration was 6.02-53.01, 15.66-71.08 and 25.30-79.52%, respectively. The rate of inhibition was corroborated with concentrations of fungicides. The findings of the study indicate that T. harzianum isolate T-10 was compatible with Provax-200 and Rovral 50 WP only at lower concentration. The biocontrol fungus showed insensitivity to all organic amendments at their lower concentrations except tea waste.
Due to their excellent effectiveness, generally species of Trichoderma are used as biocontrol agents against plant diseases. Insensitivity characters of biocontrol agents to other disease control measures especially fungicides are also desirable because such biocontrol agents are usable in integrated disease management program. Therefore, many researchers test sensitivity to selected biocontrol agents to fungicidal chemicals before recommendation to use. Available reports reveal that some species of Trichoderma are resistant to several chemical fungicides such as methyl bromide, PCNB (Pentrachloro nitrobenzene), Captan, Chlorable-M and metalaxyl (Elad et al. 1980). Such research reports are scanty in Bangladesh (Raihan et al 2003, Khandakar et al. 2010).
An in-vitro experiment was conducted to determine the effect of three fungicides namely Provax-200 (Carboxin), Rovral 50 WP (Iprodione) and Bavistin 50 WP (Carbendazim) on mycelium growth and sporulation of an isolate of T. harzianum (T-10) following “poison food technique” (Dhingra and Sinclair 1985). Each of the fungicides was tested at 50, 100, 250 and 500 ppm concentrations. Potato dextrose agar (PDA) was prepared and poured into conical flasks at 100 ml/flask. Before solidification requisite quantity of individual fungicide was thoroughly mixed with the freshly prepared PDA to have desired concentrations of individual fungicide. The amended PDA was sterilized in an autoclave at 120C under 1 kg pressure per cm2 for 20 minutes. Sterilized medium was poured into 90 mm Petri dishes at 20 ml/dish. After solidification of amended PDA, the plates were inoculated with wheat grains colonized with T. harzianum. One wheat grain was placed in the center of each plate. Plates under control received unamended PDA. The radial diameter of the fungal colony and sporulation was recorded 7 days after incubation when the control plates were covered with the growth of test isolate of T. harzianum. Percent inhibition of the radial growth and sporulation was computed following standard procedures (Sundar et al. 1995).
Another in-vitro experiment was conducted to determine the effect of mustard oil cake, tea waste, rice bran, chickpea meal and wheat meal on the growth and sporulation of the isolate of T. harzianum (T-10) following the some technique mentioned earlier (Dhingra and Sinclair 1985). All of the organic amendments were tested @ 10, 20 and 30%. Freshly prepared PDA was poured into 250 ml conical flasks at 100 ml/flask. Requisite amount of individual organic material was poured into the conical flasks and thoroughly mixed with the PDA. The amended PDA was autoclaved for sterilization. Sterilized PDA was poured into 90 mm Petri dishes at 20 ml per plate. Petri dishes under control received fresh PDA without amendment. The procedures of inoculation and data collection were the same as mentioned earlier.
The experiments were conducted in the plant pathology laboratory, Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur following completely randomized design. Data were analyzed using MSTAT-C computer program. Differences in means of the treatments were evaluated for significant following Duncan’s multiple range tests.
Effect of fungicides on growth and sporulation of T. harzianum is shown in Table 1. At different concentrations of Provax-200, inhibition in colony diameter and sporulation of T. harzianum isolate ranged 2.22-18.89% and 4.52-11.76%, respectively. In case of Rovral 50 WP, inhibition in two parameters was 7.78-22.22% and 10.07-21.04%, respectively. Complete inhibition of colony growth was obtained with Bavistin at 250 and 500 ppm. At 50 and 100 ppm, the fungicide caused 90.00 and 95.56% inhibition of colony growth, respectively. The sporulation of T. harzianum was inhibited by 90.50% at 50 ppm and 100% at three higher concentrations of Bavistin 50 WP. The rate of inhibition was corroborated with concentrations of two fungicides (Table 1).
The findings indicate that Bavistin 50 WP is highly incompatible to the growth and sporulation of T. harzianum. Inhibition in growth and sporulation of the fungus obtained with Provax-200 and Rovral 50 WP was poor, which indicates compatibility of two fungicides with T. harzianum at least at their lower concentrations. Several investigators (Mondal et al. 1995, Khandakar 2004, Nahar et al. 2007) also reported similar findings. They found that T. harzianum is highly compatibility with Provax-200 (Carboxin).
Effect of organic amendment on growth and sporulation of T. harzianum is shown in Table 2. Inhibition of colony diameter due to amendment of PDA with mustard oilcake, tea waste, rice bran, chickpea meal and wheat meal ranged 0.00-36.30, 2.22-54.07 and 6.30-72.96%, respectively. The organic amendments caused respectively 6.02-53.01, 15.66-71.08 and 25.30-79.52% inhibition in sporulation (Table 2).
Among the five organic amendments, the lowest inhibition of radial growth and sporulation was observed under mustard oilcake at the lowest concentration of 10% while the highest inhibition was observed on tea waste. In inhibiting radial growth and sporulation, wheat meal was appeared to be second lowest followed by chickpea and rice bran. The percent inhibition of mycelium growth and sporulation T. harzianum increased with increasing concentration of all the tested organic matters. Findings of the present study suggest that mustard oilcake at the lowest concentration appeared to be compatible with T. harzianum. The findings are in agreement with other investigators (Dutta and Das 1999, Islam et al. 2002, Nahar and Bhuiyan 2003). Sivan et al. (1984) reported that T. harzianum can grow on different agricultural waste products.
One of the most desirable characteristics of an antagonist is its insensitivity to the fungicides and organic amendments, which are used to control plant pathogens. Until and unless antagonists are insensitive to fungicides and organic amendments, they can not be integrated successfully for the purpose of integrated disease management strategy.
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