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Effect of Spray Interval of Rovral 50 Wp Against Alternaria Blight and Seed Yield of Cabbage

Dr. Md. Sakhawat hossain
Senior Scientific Officer
Plant Pathology Division, BARI, Gazipur

M. M. Hossain
Scientific Officer
Plant Pathology Division, Bari, Gazipur

Abstract/ Executive Summary:

An experiment was conducted at the Regional Agricultural Research Station (RARS) Jamalpur to find out the effective spray interval of Rovral 50 WP (0.2%) for the management of Alternaria blight (Alternaria brassicicola) of cabbage seed crop. Rovral 50 WP was applied at 7 days, 10 days, 12 days, 15 days and 18 days interval. Spraying Rovral at 7-15 days interval was found effective to control the disease and 7 days interval appears to be the best for the highest disease control. The yield contributing characters like pod number, pod length, per pod seed number were enhanced when fungicide was sprayed at 10 - 15 interval and 12 days interval was the best among the treatments. Seed yield per plant and per hectare was also the highest in plant sprayed at 12 days interval. Higher seed germination with lower seed-borne Alternaria obtained from plant sprayed at 10 days interval. Considering disease reduction, yield components, seed yield and quality 10-15 days may be stated as the optimum spray interval of Rovral for effective management of the disease. However, 12 days was noted as the best spray interval of Rovral for the highest yield of quality seed of cabbage with maximum disease reduction.

Keywords: Spray interval, Alternaria blight, Cabbage

Location: RARS, BARI, jamalpur

Start Date: 01-07-2004

End Date: 30-07-2006

Program Area: Pest Management

Commodity: Cabbage

Objectives:

In Bangladesh, a total of nine diseases of cabbage have been identified and Alternaria blight caused by Alternaria. brassicae (Berk) Sacc. and A. brassicicola (Schew) Wiltshire is considered to be the major. Alternaria brassicicola causes tremendous loss to cabbage seed yield through foliar destruction leading to reduce flowering and pod formation. There has been a multifarious effort to control different diseases of crops. Crop disease management with chemical is very much popular because of its quick action, broad spectrum and easy availability to the growers. However, the issue of environmental pollution is linked with indiscriminate and unplanned use of chemicals which provokes health hazard. So, minimum rate and frequency of chemical spray is sought. Rovral 50 WP has been used successfully in controlling the Alternaria blight of cabbage but investigation for suitable spray interval of it for maximum disease reduction is yet to be done. Therefore, the present experiment was under taken at Regional Agricultural Research Station (RARS), Jamalpur to find out the effective spraying interval of Rovral 50 WP for the management of Alternaria blight of cabbage seed crop.

Methodology:

The experiment was conducted during the winter season of 2003-2004 and 2004-2005. Rovral 50 WP (0.2%) was applied in five different spray intervals viz., 7 days, 10 days, 12 days, 15 days and 18 days. A control treatment (spaying with plain water) was maintained for comparison. The experiment was laid out in a Randomized Complete Block Design (RCBD) with three replications. Recommended rate of manure and fertilizers were applied in the bed before transplanting (Sattar et al. 2005). Thirty days old seedlings of BARI Cabbage-2 (Agradute) were transplanted in 2 m x 1 m plots in the field on November 1. Fifty-centimetre wide and 30 cm deep drain was made surrounding each block for facilitating irrigation and drainage. Ten seedlings were transplanted in each plot in two rows at 50 cm x 40 cm spacing. Subsequent weeding, mulching and irrigation were done as and when necessary. Spraying of fungicides was started immediately after onset of disease and continued up to pod maturity stage. Aphid infestation was controlled by spraying Malathion 57 EC @ 1.5 ml/ l.

When 70% pods of the plant showed the symptoms of maturity (partial yellowing) 5 plants from each plot were randomly selected and tagged for data collection. Data on Alternaria blight component {percent pod infection, number of spot per pod and percent disease index (PDI) of pod spot}, yield component (number of pod per plant, pod length, number of seed per pod, 1000 seed weight), seed yield (per plant and per hectare) were recorded.

Source of Information: Annual Report (2006-07). Palant Pathology Division, BARI, Gazipur. 50-51 pp.

Article Link (Online Journal):

Funding Source:

1. Government

Budget:

Total Budget (Tk.) :

Achievement/Findings:

Disease severity: Spraying of Rovral 50 WP significantly reduced all the parameter of disease severity over control. The lowest pod infection percentage was observed at 7 days interval followed by 10, 12, 15 and 18 days interval, respectively in both crop seasons (Table 1). The lowest and statistically similar number of spot/ pod was recorded at 7 and 10 days spray intervals in both cropping seasons. In 2003-2004 crop season the effect of 12, 15 and 18 days spray intervals and in 2004-2005 crop season 7, 10 and 12 days spray intervals were statistically similar but significantly lower than the control treatment. Irrespective of spray intervals, the effect of fungicide on PDI of pod spot was significant as compare to control in 2003-2004 but the effect of treatments were statistically similar. In 2004-2005 crop season the lowest PDI was recorded on 7 days interval followed by 10 and 12 days interval but the effect of these treatments was statistically similar. effect of 10, 12, and 15 days interval were also statistically similar and 12, 15 and 18 days interval were also had statistically similar effect on PDI.

Yield component: Different spray intervals had significant effect on pod number. The highest number of pod/ plant was recorded from plots sprayed at 12 days interval in 2003-2004 and 10 days interval in 2004-2005 cropping season. However, the number of pod/ plant obtained from plot sprayed at 7, 10, and 12 days interval were statistically similar in both the study seasons. In 2003-2004 crop season the number of pod/ plant obtained from plots sprayed at 15 and 18 days intervals were statistically similar but significantly higher than the control plot. In 2004-2005 season 18 spray interval had no significant effect on pod production. The longest pod were recorded in plots sprayed at 12 days interval in both the cropping seasons but the effect of spray interval on pod length was non significant. The highest number of seed/ pod was recorded in pod harvested from plot sprayed at 12 days interval followed by 10 days interval but the effect of treatments on that parameters was non significant. In 2004-2005 crop season the highest number of seed/ pod was recorded from 12 days interval followed by 10 days interval. However, the effect of 7, 10, 12 and 15 days spray interval on seed number/ pod was statistically similar but significantly higher than the control plots. Effect of 18 days spray interval on per pod seed number was non significant compare to control. The effect of different spray intervals on 1000 seed weight was also non significant in both the study seasons.

Seed yield: The significantly highest seed yield/ plant was obtained from plots sprayed at 12 days interval in both the crop seasons. In 2003-2004 statistically similar per plant seed yield was recorded at 7, 10, 12 and 15 days interval. The effect of 18 days spray interval on per plant seed yield was non significant as compare to control in both the study seasons. In 2004-2005, significantly the highest and statistically similar per plant seed yield was recorded from 10, 12 and 15 days interval followed by 7 and 18 days interval that were statistically similar but significantly higher than the control treatment (Table 2). In 2003-2004 cropping season, the highest seed yield / ha was recorded from plots sprayed at 12 days interval. Per hectare seed yield obtained from plant sprayed at 7, 10, 15 and 18 days interval was statistically similar but significantly higher than the control treatment. In 2004-2005, the highest seed yield/ ha was recored from 12days interval that was statistically similar with 10 and 15 day spray interval. Statistically similar per hectare seed was obtained from 7 and 18 days interval but that were significantly higher than the control.

Knowledge Management: Report/Proceedings