EFFICACY OF TWO FUNGICIDES AND TWO BOTANICALS TO CONTROL FOOT AND ROOT ROT DISEASE (SCLEROTIUM ROLFSII) OF COWPEA
Z. Rahman, A. H. M. Mafuzul Haque, M. A. Zaman, M. F. Amin, and A. K. Das. 2012. Efficacy of two fungicides and two botanicals to control foot and root rot disease (Sclerotium rolfsii) of cowpea. Bangladesh J. Plant Pathol. 28 (1&2): 29-32.
Effect of two fungicides Provax-200 (Carboxin + Thiram) @ 0.25%, and Bavistin 50 WP (Carbedazim) @ 0.25 %, two botanicals, Neem leaf extract (1:1), and Garlic clove extract (1:1) along with Clean seed and control (untreated seed) were tested under field conditions to control foot and root rot disease (Sclerotium rolfsii) of cowpea. Among the treatments Provax-200 was the most effective followed by Bavistin 50 WP, Neem leaf extract and Garlic clove extract with respect to disease reduction and increase of seed yield. Maximum germination (85.53%), disease reduction (40.67%) and seed yield (1353 kg/ha) were obtained when seed was treated with Provax-200 @ 0.25 % followed by Bavistin 50 WP @ 0.25 %.
Cowpea (Vigna unguiculata) is one of the important crops of coastal and hilly areas of Bangladesh where it is grown as pulse, fodder and green manure. People of hilly areas under Chittagong division use it as a staple pulse. The crop suffers from many diseases but foot and root rot caused by Sclerotium rolfsii is a major one (Talukder 1974, Ahmad and Hossain 1985). The disease is also known as wilt and stem rot (Dutta 1975). The fungus can attack the crop from seedling to flowering stage and are comparatively more destructive at seedling stage. The disease substantially reduces the crop yield annually (De Waard 1979). As the organism is soil – borne it is difficult and expensive to manage it. Good number of fungicides inhibit the germination of sclerotia or mycelial growth of the fungus and effectively control the disease of various crops in the field (Tiwari 1987). Resistant variety of the crop is not yet available. Many researchers tried to control the pathogen by chemical and botanicals means on many other crops (Prasad et al. 1977, Arun et al. 1995, Sinha and Sinha 2004, Rana 2006, Fatema 2007). Seed treatment with fungicides or botanicals may be effective to control the disease.
The present experiment was conducted to evaluate the efficacy of seed treatment with two fungicides and two botanicals for control of foot and root rot disease of cowpea caused by S. rolfsii.
MATERIALS AND METHODS
Two fungicides namely Provax-200 (Carboxin + Thiram) @ 0.25%, and Bavistin 50 WP (Carbedazim) @ 0.25%, and two botanicals namely Neem leaf extract (1:1), and Garlic clove extract (1:1) were tested in the experiment in six different treatments. The treatments (including control) were Provax-200, Bavistin -50 WP, Neem (Azadirachta indica) leaf extract (1:1), Garlic (Allium sativum) clove extract (1:1), seed cleaning and control (untreated seed).
The experiment was conducted at the Regional Agricultural Research Station, BARI, Hathazari, Chittagong during 2009-10 and 2010-11cowpea growing seasons. Cowpea variety BARI Felon-1 was used in the experiment. Size of unit plot was 4.0 m x 4.0 m and plant to plant spacing was 50 cm x 10 cm. The experiment was conducted under natural infection condition. Recommended doses of fertilizers and manure were used. Irrigation and weeding were done as and when necessary. Seeds of a cowpea variety (BARI Felon-1) were treated with the fungicides separately @ 2.5 g/kg (0.25%) before sowing. Required amount of seeds and individual fungicides were taken in a conical flask, few drops of sterilized water were added and shaken well with hands for 10 minutes. To prepare the standard plant extracts solution (100%), fresh leaves of Neem leaf and garlic cloves were collected, washed and crushed with sterilized distilled water at the rate of one gram tissue in one milliliter of water (1:1w/v) separately as described by Shindhan et al. (1999). Seeds were uniformly coated with the plant extracts. Required amount of seeds and individual plant extract were taken in a conical flask and thoroughly mixed by shaking with hands for 10 min. In other two treatments clean seeds and seeds washed with sterilized distilled water (control) were used. Treated seeds were air dried for 30 min and sown in the field.
The experiment was carried out in randomized complete block design with three replications. Data on germination, pre-emergence mortality and post-emergence mortality, yield and yield contributing characters of the plant were recorded. The data were analyzed statistically and means per treatment were compared using least significant difference test (P=0.05).
RESULTS AND DISCUSSION
During 2009-2010, pre and post emergence seedling mortality of cowpea ranged 5.65-17.11 and 5.75-17.07%, respectively. During 2009-2010, the ranges of two parameters were 5.65-17.11 and 5.75-17.07%, respectively. The lowest seedling mortality was observed in seeds treated with Provax-200 and the highest under control. All treatments with two fungicides, two botanicals and clean seeds significantly reduced seedling mortality compared to control during both the years. The highest reduction in pre and post emergence mortality was achieved with two fungicides followed by botanical and clean seed in both years. The reduction in disease severity was 8.46-37.83% during 2009-2010 and 11.00-40.67% during 2010-2011 (Table 1).
Germination and seed yield ranged 61.44-84.68% and 740-1327 kg/ha, respectively during 2009-2010, and 60.80-85.53% and 753-1353 kg/ha, respectively during 2010-2011. The highest germination and seed yield were observed when seeds were treated with Provax-200 and the lowest under control. All treatments with fungicides, botanicals and clean seed gave significant increase in germination as well as grain yield compared to control during both the years. Every year, the maximum increase in both the parameters was achieved with two fungicides followed by two botanicals and clean seed. Efficacy of Provax-200 was better than Bavistin 50 WP. The increase of germination was 24.79-59.56% and that of yield was 40.79-74.61% over control during 2009-2010. The increase in both the parameters was slightly higher during 2010-2011 than 2009-2010 (Table 1).
The data on most important yield contributing parameters such as plant height, branch and pod number/plant, pod length, seed/pod and seed size recorded during 2009-2010 and 2010-2012 crop seasons were almost similar. Therefore, only second year’s data on those yield attributes are presented in the Table 2. Plant height and branch number ranged 42.72-43.87 cm and 4.7-4.57/plant, respectively under different treatments including control. However, the variations in both parameters under different treatments were not significant. Seed treatment with fungicide as well as botanicals and use of clean seed caused significant increase over control in pod number per plant and seed number per pod, which are most important yield attributes of cowpea. All treatments with two fungicides and two botanicals gave significant increase in pod length and 1000-seed weight compared to control (Table 2). The highest increase in pod number/plant, pod length, seed number/pod and 1000-seed weight was obtained with Provax-200 treatment followed by Bavistin 50 WP and Neem leaf extract. The lowest increase of those parameters was obtained with clean seeds followed by Garlic clove extract (Table 2).
Results of the present experiment reveal that seed treatment with Vitavaxe-200, Bavistin 50WP, Neem leaf extract and Garlic clove extract cause appreciable reduction in foot and root rot severity and substantial increase in plant growth and grain yield of cowpea. Many other workers also reported that seed treatment with Vitavax-200 improved germination, yield contributing characters and yield of wheat (Deway and Albrechten 1977, Singh and Saksena 1986). In case of seed treatment, higher number of grain per spike, number of spikelet per spike and ultimately increased yield were obtained by Singh and Saksena (1986), Dey et al. (1992), Deway and Albrechtsen (1997).
Findings of the present study indicate that significant reduction of seedling mortality and thereby increased germination and crop yield of cowpea can be achieved with seed treatment with fungicides as well as botanicals. On the basis of the findings of two year’s experiment, it can be noted that Provax-200 and Bavistin 50 WP are effective to control foot and root rot disease and to increase germination and seed yield of cowpea.
Based on results of the present investigation it may be concluded that pre sowing seed treatment with Provax-200 (0.25%) and Bavistin 50 WP (0.25%) is effective to control foot and root rot (S. rolfsii). Efficacy of Neem leaf extract and Garlic clove extract (1:1w/v) as seed treating botanicals is almost at par with the fungicides tested.
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