Efficacy of various fungicides on growth of Colletotrichum musae Berk. & Curt. Causing banana anthracnose in vitro

Abstract

Banana is one of the important fruit crops and economically profitable crop of India having high export potential. Cultivated banana is susceptible to many diseases, among them Colletotrichum musae has been the most notorious fungal pathogen. C. musae infects wounded green fruits and also ripe fruit, as well as has been reported causing crown and tip rot of banana. The anthracnose symptoms appeared as peel blemishes, black or brown, sunken spots on banana fruits. The spots bear masses conidia and salmon coloured acervuli sometimes. To know the effect of different 20 fungicides viz., non systemic (chlorothalonil, mancozeb, copper oxychloride, copper hydroxide, captan, wettable sulphur at 500, 1000, 1500 and 2000 ppm), systemic (carbendazim, benomyl, fosetyl-Al, metalaxyl, propiconazole, thiophanate methyl, picoxystrobin at 50, 100, 250 and 500 ppm) and readymix  captan+hexaconazole, azoxystrobin+tebuconazole, zineb+hexaconazole, tebuconazole+trifloxystrobin at 100, 250, 500 and 1000 ppm) fungicides were tested for their effect on mycelium growth of Colletotrichum musae using poisoned food technique at four concentrations. Among them, in case of non systemic fungicides, cent per cent mean growth inhibition of test fungus was observed in mancozeb 75% WP at 2000 ppm and found significantly superior over all other fungicides. Looking to the systemic fungicides, the results revealed that among the all seven fungicides, carbendazim 50% WP at 50, 100, 250 and 500 ppm was found superior and gave cent per cent inhibition of test pathogen. Among the different seven ready mix fungicides the mixture of carbendazim 12%+mancozeb 63% WP at 100, 250, 500 and 1000 ppm were significantly superior among all the fungicides with cent per cent mean growth inhibition.

Keywords

Banana anthracnose; Fungicides; Colletotrichum musae; In vitro; Growth inhibition

INTRODUCTION

Banana (Musa paradisiaca L.) belongs to the family musaceae is one of the most important crops in tropical and subtropical countries. Banana is popularly known as “poor man’s fruit”. In many Asian and African countries, banana is an important staple food crop next to rice, wheat, and maize. In India, annual production of banana is 308.09 lacs MT from an area of 8.84 lacs ha has spread all over the country with the productivity of 34.86 MT/ha. In India, Gujarat holds first position among all states in production of banana by annual production of 41.85 lacs MT from an area of 0.65 lacs ha with the productivity of 64.70 MT/ha [1]. Based on gross value, it is considered to be the fourth most important food crop in the world after rice, wheat and milk/milk products. Banana is second most important fruit crop in India. Bananas are highly perishable commodities with post-harvest losses estimated to the tune of 25-30 per cent [2]. During post-harvest storage and handling of banana, among the various plant disease control approaches, fungicides gave maximum control of banana anthracnose.

MATERIALS AND METHODS

Different 20 fungicides viz., non-systemic (chlorothalonil 75% WP, mancozeb 75% WP, copper oxychloride 50% WP, copper hydroxide 53.8% WP, captan 75% WP and wettable sulphur 80% WP) at 500, 1000, 1500 and 2000 ppm; systemic (carbendazim 50% WP, benomyl 50% WP, fosetyl-Al 80% WP, metalaxyl 72% WP, propiconazole 25% EC, thiophanate methyl 70% WP and picoxystrobin 25% EC) at 50, 100, 250 and 500 ppm and readymix fungicides (carbendazim 12%+mancozeb 63% WP, carbendazim 37.5%+thiram 37.5% DS, metalaxyl 8%+mancozeb 64% WP, captan 70%+hexaconazole 5% WP, azoxystrobin 11%+tebuconazole 18.3 % SC, zineb 68% WP+hexaconazole 4% WP, tebuconazole 50%+trifloxystrobin 25% WG) at 100, 250, 500 and 1000 ppm concentration were tested for their effect on mycelium growth of C. musae using poisoned food technique [3]. The technique involved cultivation of test organism on a medium containing the test chemical.

In all experiments PDA was used as a basal medium. The calculated quantities of fungicides were thoroughly mixed in the molten almost cool PDA medium before pouring into Petriplates aseptically, so as to get desired concentration of each fungicide separately. Twenty millilitre of fungicide amended medium was poured in each 90 mm sterilized Petri plates and allowed to solidify. The plates were aseptically inoculated with 5 mm disc cut from the periphery of 7 days of old actively growing cultures of C. musae. Control without fungicides amended was maintained for comparison. The experiments were conducted in factorial completely randomized design with three repetitions of each treatment and the inoculated plates were incubated at 25 ± 2°C. The colony diameter was measured after 10 days when the control plates were full of fungal growth. Per cent inhibition of growth of mycelium for each treatment was calculated by using the formula given by Vincent [4].

RESULTS AND DISCUSSION

Evaluation of different non-systemic fungicides

The relative efficacy of six different non-systemic fungicides was tested against C. musae at four concentrations. The observations regarding per cent inhibition of linear growth are presented in Table 1. The results revealed that all the non systemic fungicides tested were capable of inhibiting the fungal growth at all the concentrations tried in the present investigation. Their mean inhibitions were ranged from 43.94 to 94.55 per cent. Among the all six fungicides tested maximum mean inhibition of C. musae was observed in mancozeb 75% WP (94.55%) and found significantly superior over all other fungicides. Next effective fungicide was captan 75% WP (91.07%) followed by chlorothalonil 75% WP (89.85%) and reported better then rest of the fungicides. In comparison to these, other treatments showed lower inhibition which was copper hydroxide 53.8% WP (64.71%), copper oxychloride 50% WP (46.64%). Wettable sulphur 80% WP (43.94%) noted inferior for growth inhibition.

The positive correlation was found between concentration and growth inhibition of test pathogen. It was observed that with increasing concentration in all fungicides, growth inhibition of pathogen also increased. All four concentrations of all fungicides were found differing from each other. At higher concentrations of 2000 ppm, all the fungicides gave significantly more inhibition as compared to their lower level of concentrations. Within the concentrations, the outcome of per cent growth inhibition indicated that mancozeb 75% WP at lower concentration 500 ppm (90.91%) was at par with its higher concentration 1000 ppm (92.12%). Copper oxychloride 50% WP at 1500 ppm (58.79%) and 2000 ppm (60.59%) were statistically at par with each other. Wettable sulphur 80% WP at 1000 ppm (46.18%) was at par with its 1500 ppm (47.15%) concentration.

Looking to the interactions of fungicides and concentrations, among the all six non-systemic fungicides tested cent percent inhibition of pathogen was found in presence of mancozeb 75% WP (100%) at higher concentration of 2000 ppm which was at par with captan 75% WP (100%) at same level of concentration. The first superior fungicide mancozeb 75% WP, at 1500 ppm (95.15%) was at par with chlorothalonil 75% WP at 2000 ppm (93.94%). Secondly mancozeb 75% WP at 1000 ppm (92.12%) was statistically at par with chlorothalonil 75% WP at 1500 ppm (90.91%), mancozeb 75% WP at 500 ppm (90.91%), captan 75% WP at 1500 ppm (90.31%). Captan 75% WP at 1000 ppm (88.49%) was statistically at par with its 500 ppm (85.46%) and chlorothalonil 75% WP at 1000 ppm (88.48%) and its 500 ppm (86.06%).

Table 1. Effect of different non-systemic fungicides on growth inhibition of C. musae in vitro.

These results are in general agreement with the report of Ekbote, et al. and Gaikwad who observed cent per cent inhibition of Colletotrichum at 0.3% and 0.2% mancozeb, respectively [5,6]. Similar results were also obtained by Venkataramanappa, et al. and Nath, et al. [7,8].

Evaluation of different systemic fungicides

For testing the efficacy of systemic fungicides on growth inhibition of C. musae different seven fungicides were tested at four concentrations. The per cent inhibition of mycelial growth recorded and presented in Table 2.

The perusal of data presented in the Table 2 showed that all fungicides were capable of inhibiting mycelial growth at all concentrations tried in the present investigation. Their mean inhibition ranged from 39.22 to 100 percent.

The results indicate that all seven systemic fungicides tested against C. musae were significantly differing from each other in mycelia growth inhibition. Among the all seven fungicides, the cent per cent mean inhibition of mycelial growth was found in carbendazim 50% WP and remained superior than the rest of the systemic fungicides. Next effective fungicide was propiconazole 25% EC showing 88.93% mean growth inhibition. Another systemic fungicide benomyl 50% WP (75.41%) was moderately effective in mean mycelial growth inhibition. More than 50% mean growth inhibition was found in fosetyl-Al 80% WP (58.39%) and thiophanate methyl 70% WP (52.87%). Minimum mean growth inhibition was found in picoxystrobin 25% EC i.e., 39.22 percent. The positive correlation was found between concentration and growth inhibition of pathogen. It was observed that with increasing concentration with all fungicides, growth inhibition of pathogen also increased. All four concentrations of all fungicides, except carbendazim 50% WP, were significantly differing from each other. At higher concentrations of 500 ppm all the fungicides gave significantly more inhibition as compared to their lower level of concentrations.

Within the concentration, the outcome of per cent growth inhibition at each concentration level of carbendazim showed cent per cent mean inhibition. Except that at 50, 100, 250 and 500 ppm, highest growth inhibition was found in propiconazole 25% EC with 83.33, 86.20, 92.52 and 93.68 per cent, respectively. More than 50% growth inhibition was found in benomyl 50% WP 54.49, 72.41, 83.90 and 90.85 per cent, respectively. The least growth inhibition was found in picoxystrobin 25% EC 13.79, 28.16, 43.67 and 71.25 per cent, respectively. Looking to the interactions of fungicides and concentrations, within the all concentrations of all fungicides, carbendazim 50% WP found superior and showed cent per cent growth inhibition of pathogen at each level of concentrations. Propiconazole 25% EC at 500 ppm (93.68%) and its 250 ppm (92.52%) were at par with each other. Propiconazole 25% EC at 100 ppm (86.20%) was at par with benomyl 50% WP at 250 ppm (83.90%). Whereas, benomyl 50% WP at 250 ppm (83.90%) was also statistically at par with propiconazole 25% EC at 50 ppm (83.33%). Thiophanate methyl 70% WP at 500 ppm (73.56%) was at par with benomyl 50% WP at 100 ppm (72.41%) and higher concentration (500 ppm) of picoxystrobin 25% EC (71.25%) and metalaxyl 72% WP (70.43%).

Effectiveness of carbendazim on growth inhibition was also obtained by Frossard, et al., Datar and Ghule, Gaikwad and Nath, et al. [9,10]. Similar results showing the maximum growth inhibition by carbendazim, propiconazole and benomyl were also observed by Ramma, et al., Patel and Joshi, Patel, Nath, et al. and Nath, et al. [11-14].

Table 2. Effect of different systemic fungicides on growth inhibition of C. musae in vitro.

Evaluation of different ready mix fungicides

The relative efficacy of seven different ready mix fungicides was tested at four concentrations. The observations regarding per cent inhibition of linear growth are presented in Table 3.

The results indicate that among the all seven ready mix fungicides significantly the most effective fungicide was carbendazim 12%+mancozeb 63% WP with cent per cent mean growth inhibition closely followed by carboxin 37.5%+thiram 37.5% DS with 93.51 per cent inhibition. However, azoxyystrobin 11%+tebuconazole 18.3 % SC (77.53%) and tebuconazole 50%+trifloxystrobin 25% WG (72.18%) also recorded well in mean growth inhibition of pathogen. More than 50% mean mycelial growth inhibition were observed in all fungicide combinations, except zineb 68% WP hexaconazole 4% WP (40.66%) and metalaxyl 8%+mancozeb 64% WP (34.65%) which showed minimum mean mycelial growth inhibition.

There was also found positive correlation between concentration and growth inhibition of pathogen. It was observed that with increasing concentration with all fungicides, growth inhibition of pathogen also increased. All four concentrations of all fungicides, except carbendazim 12%+mancozeb 63% WP and carboxin 37.5%+thiram 37.5% DS at higher concentrations of 500 and 1000 ppm were significantly differing from each other at all concentrations. At higher concentrations of 1000 ppm all the fungicides gave significantly more inhibition as compared to their lower level of concentrations. Within the interaction effect of all concentrations of all fungicides, carbendazim 12%+mancozeb 63% WP found superior and at par with each other at each level of concentrations showed cent per cent growth inhibition of pathogen. Carboxin 37.5%+thiram 37.5% DS at 500 and 1000 ppm also showed cent per cent inhibition and at par with superior treatment.

The results obtained were also supported by the findings of Venkataramanappa, et al., Nath, et al. and Nath, et al.

Table 3. Effect of different fungicide combinations on growth inhibition of C. musae in vitro.

CONCLUSION

In conclusion, the study on the efficacy of various fungicides against Colletotrichum musae, the causative agent of banana anthracnose, provides valuable insights into effective management strategies for this damaging fungal pathogen. The findings from this in vitro investigation underscore the importance of selecting appropriate fungicides to control the spread of banana anthracnose, especially during post-harvest storage and handling, where the disease often leads to significant losses.

Among the non-systemic fungicides tested, mancozeb 75% WP demonstrated the highest efficacy, achieving 100% inhibition of mycelial growth at the highest concentration (2000 ppm). This result aligns with previous studies indicating the effectiveness of mancozeb in controlling fungal pathogens, including Colletotrichum species. Other non-systemic fungicides like captan and chlorothalonil also showed promising results, making them suitable candidates for managing banana anthracnose, particularly in integrated disease management programs.

The systemic fungicides tested in this study, particularly carbendazim 50% WP, exhibited complete inhibition of mycelial growth at all concentrations, making it a standout choice for controlling C. musae. This result is consistent with existing literature that recognizes carbendazim as an effective fungicide against a range of fungal pathogens. Similarly, propiconazole and benomyl showed substantial efficacy, though their performance was not as superior as carbendazim.

The ready-mix fungicides, particularly the combination of carbendazim 12%+mancozeb 63% WP, provided excellent results with 100% inhibition at all concentrations, making it a highly effective option for managing anthracnose in bananas. These formulations combine the strengths of both systemic and non-systemic components, enhancing their overall performance. The study highlights that fungicides, particularly mancozeb, carbendazim, and effective combinations, offer significant potential for controlling banana anthracnose. However, it is important to consider the environmental impact, cost effectiveness, and resistance management when selecting fungicides for large-scale application. Future research should explore the development of fungicide-resistant strategies and integrate biological control methods for sustainable disease management in banana production.