Management of Faba Bean Gall Disease (Kormid) in North Shewa Highlands, Ethiopia

Bitew B^* and Tigabie A

Debre Birhan Agricultural Research Center, PO Box 112, Debre Birhan, Ethiopia

Corresponding Author:

Beyene Bitew
Debre Birhan Agricultural Research Center
PO Box 112, Debre Birhan, Ethiopia
Tel: 911338789
Fax: 911338789
E-mail: beyenebitew@yahoo.com

Received date: April 22, 2016; Accepted date: May 16, 2016; Published date: May 26, 2016

Citation:Bitew B, Tigabie A (2016) Management of Faba Bean Gall Disease (Kormid) in North Shewa Highlands, Ethiopia. Adv Crop Sci Tech 4:225. doi:10.4172/2329-8863.1000225

Copyright: © 2016 Bitew B, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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Abstract

Production of faba bean is inhibited by several yield limiting factors, among which diseases are the main. In Ethiopia more than 17 disease causing pathogens were reported on faba bean. Major diseases recoded in faba bean includes, chocolate spot (Botrytis fabae), rust (Uromyces viciae-fabae), ascochyta blight (Ascochyta fabae), zonate leaf spot (Cercospora zonatae), and black root rot (Fusarium sp.). A new disease, faba bean gall locally called “Kormid in North Shewa was expanded in the highland faba bean growing areas. Studies showed that seed dressing and foliar fungicides have some effects against faba bean diseases. Field experiment was conducted in North shewa highlands to control faba bean gall disease at farmers’ field. The experiment was conducted on farmers’ fields in randomized complete block design in six replications. The treatments were arranged with different fungicides (spray and seed dressing), namely Mancozeb, Ridomil, Chlorotalonil, Bayleton wp 25 (Triadimefon 250 g/ kg), Thiram, Apron star and control. Fungicides were applied as manufacturers’ recommendations. Foliar fungicides were applied three times at seedling, flowering and podding growth stage on local faba bean variety. Disease score and other agronomic data were recorded at different plant growth stage. The highest disease score were recorded in control, Thiram and Apron star in 2013. The highest yield was also recorded in Bayleton and mancozeb sprayed plots respectively. In 2014 the disease prevalence and severity was similar to 2013. Maximum disease score were recorded on Control followed by Thiram and Apron star seed dressing plots. Minimum disease score were also recorded in Baylaton (2.66) and Ridomil gold (2.71) sprayed plots. There was a significant difference between biomass yield and grain yield. The highest grain yield was recorded in Baylaton (3129.8 kg) sprayed plot and followed by Ridomil gold (2708.3 kg) and Mancozeb (2705.7 kg) respectively. There was no significant difference between plots in plant height, pod per plant, seed per pot and seed per plant in both years.

Keywords

Disease; Faba bean; Faba bean gall; Incidence; Prevalence; Severity

Introduction

Ethiopia is the world’s second largest producer of faba bean, but its share is only 6.96% of world production and 40.5% of Africa [1]. Faba bean (Vicia fabae L.) is the major cool season food legumes produced in Ethiopia next to cereals. It serves as major source of protein & income. The crop also fixes atmospheric nitrogen and improves soil fertility. Because of its wide importance to the nation it is cultivated in large area in the country as well as in Amhara region. Production of faba bean is inhibited by several yield limiting factors, among which diseases are the main [2]. In Ethiopia more than 17 disease causing pathogens are reported on faba bean [3]. Major diseases recoded in faba bean includes, chocolate spot (Botrytis fabae), rust (Uromyces viciae-fabae), ascochyta blight (Ascochyta fabae), zonate leaf spot (Cercospora zonatae), and black root rot (Fusarium sp).

Currently a new disease faba bean gall locally called “Kormid in North Shewa is expanded in the highland faba bean growing areas of North. It was first observed in Menze Mama District around Bash kebele in farmers’ fields in 2010/2011 main cropping season [4]. Seed dressing & foliar fungicides have some effects against faba bean diseases [5,6]. Report reveals that, chemical control showed better results in controlling gall disease in China and Japan [7]. Hence this study was initiated with the following objectives: to select the right and effective fungicides on gall disease (kormid) on faba bean.

Materials and Methods

The experiment was conducted on farmers’ fields in RCB design with six replication (one farmer field was used as one replication). The experiment was done with foliar and seed dressing fungicides. The treatments were arranged with different fungicides (spray and seed dressing), namely Mancozeb, Ridomil, Chlorotalonil, Bayleton wp 25 (Triadimefon 250g/kg),Thiram, Apron star & control. The plot size was 3.2m × 4m & spacing between rows 0.4m & 1m between replications. Fungicides were applied as manufacturers’ recommendations. Foliar fungicides were applied three times (at the time of diseases appearance (seedling) and repeated two times before start of flowering and podding stage). Local faba bean variety was used and seed rate was applied as recommendation in row planting.

Data collected

Date of seedling emergence, first date of disease appearance, disease score (1-9) scale and converted to percent incidence and severity. Plant height, Number of pod per 10 plant, number of seed per pod, thousand seed weight, biomass and seed yield (grain yield) were recorded.

Data analysis

Analyses of variances for the experiment was done and mean comparisons were carried out using Duncan’s multiple range test (DMRT) at 5% level of probability. The statistical analysis system (SAS) software [8] was used for all statistical analyses.

Result and Discussion

Foliar fungicides were applied at the beginning of symptom appearance. All foliar fungicides were applied at seedling, flowering and podding growth stage. The disease was very serious in first year (2013). But due to higher rainfall, there was high erosion problem and hail damage at seedling stage. The symptom of the disease starts from seedling stage & more severe up to flowering growth stage. In severely infected fields, the disease expands to the stem and the whole plant showed shrinked, shortened and died on control plots. The lowest disease score were recorded on Bayleton, chlorotalonil and mancozeb sprayed plots (Table 1). Among fungicides sprayed better grain yield were recorded on bayleton (2124.0kg), Mancozeb (1702.3k1702.3kg), Ridomil gold (1471.7kg) and chlorothalonil (1470.9kg) respectively. Apron star and Thiram seed dressing fungicides were not effective against the disease. It was similar with control plots (Table 1).

Table 1: Disease score and yield of faba bean in North Shewa 2013.

Values within a column followed by same letter do not differ significantly at 5% level of Duncans Multiple Range Test

 In 2014 the disease prevalence and severity was similar to 2013. Disease score and other agronomic data were recorded at different plant growth stage. Maximum disease score were recorded on Control followed by Thiram and Apron star seed dressing plots. Minimum disease score were also recorded in Baylaton (2.66) and Ridomil gold (2.71) sprayed plots. There was a significant difference between biomass yield and grain yield. The highest grain yield was recorded in Baylaton (3129.8kg) Figure 1 treated plot and followed by Ridomil gold (2708.3kg) and Mancozeb (2705.7kg) respectively (Table 2). There was no significant difference between plots in plant height, pod per plant, seed per pot and seed per plant. Chemical control: treat seeds with fungicides. Studies showed that Thiram, at a dosage of 0.6-1.0 kg/100 kg of seed, 25% Bayleton or 15% Bayleton, at a rate of 0.3% to seed weight, are effective in controlling galls (ICARDA, 1993), but thiram was not effective against the disease.

Table 2: Disease score and yield of faba bean in North Shewa 2014.

Values within a column followed by same letter do not differ significantly at 5% level of Duncans Multiple Range Test, Economic analysis of management options, Cost benefit analysis, Related terms in cost benefit analysis

Total variable costs: the costs of chemicals, fertilizer and labor.

Gross yield: the total output per hectare of the produce of grain and straw.

Adjusted yield: The difference that gross yield is reduced by 10% from the actual due to risk and uncertainty.

Gross benefit: is the product of output and farm get prices of the produce.

Net benefit: is the difference between the gross benefit and the costs of production that vary.

Rate of return (RR): is the rate net benefit to cost of production or benefit cost ratio (BCR).

Information generated from cost benefit analysis is the most important factor to take into account when making correct decision and lack thereof will inevitably lead to suboptimal allocation of limited resources. The only way of determining how the resources allocated for the production of crops for small holder farmers should be put to use based on evaluating the costs and benefits of all (possible) ventures and selecting treatments having the highest return. Cost benefit analysis can be calculated using partial budget analysis method. Partial budgeting is a planning and decision-making framework used to compare the costs and benefits of alternatives faced by a farm business. Gross yield was adjusted from the output obtained lowered by 10% from the actual yield due to management and other production risks (Table 3).

Table 3: Chemical costs and yields of faba bean for treatments.

Partial budget analysis

Partial budget analysis is concerned with evaluating the consequences of changes in treatments that affect only parts than whole. It is budgeting in relation to a partial change to a given farm inputs/budgets. For the evaluation of each treatment only variable costs were included and fixed costs were excluded. The net benefit or farm profit was calculated as net benefit is equal to gross benefit reduced by the costs of inputs and labor. The result was obtained from the farm get price at immediate harvest of grain and straw with 6 and 1.65 Birr per kg, respectively. Labor cost is related to chemical applications and fertilizer cost is the costs incurred for the amount of fertilizer applied based on recommendation. The analysis considers only the treatments that are most candidates having the market prices for full cost information. The result indicated that the treatments that have high net benefit are recommended for future technology packages. From the evaluation bayleton, mancozeb and redomil gold were the most competitive treatment evaluated against the control (Table 4).

Table 4: Cost benefits analysis of treatments.

Sensitivity analysis

Sensitivity analysis is important to evaluate the impact of such changes on economic parameters on the net returns for each treatment studied. Farm budgets may not expect positive net profits as a result of unexpected changes in yield, market prices or production costs. Those can quickly turn the expected benefit into a loss. Analyzing how changes in key budgeting assumptions/components affect income and cost projections is called sensitivity analysis. One way of trying to handle the problems of applying correct weights to risk is checking the outcomes using sensitivity analysis for future production guarantee. Sensitivity analysis allows the producer to have such information to control probabilities of calculating risks. Such changes are evaluated by creating future assumptions that are more or less dubious “scenarios”. Hence, sensitivity analysis was carried out to assess the changes in net benefits of treatments based on the scenarios assumed to be changed. The scenarios cover at least a couple of possible outcomes, usually including a “worst case” scenario and “normal” scenario. The normal considers the existing situations in the given time period. This analysis focused on the following scenarios.

1. When yield reduced by 10% but, cost of production remain unchanged.

2. When cost of production increased by 10% while yield is remain unchanged.

3. When both changes happen at a time.

Based on these situations the gross benefit and the net benefit can be changed accordingly. The result indicated that yield reduction of faba bean for all treatments are highly sensitive than cost of production changes. Baylaton and Mancozeb chemicals are more profitable than other management alternatives in all circumstances (Table 5).

Table 5: Sensitivity analysis result for the best treatments against the changes assumed compared with the check.

Rate of Return (RR) analysis

Rate of return is the rate of change of returns to the rate of change of investment costs. Calculations of returns on investment resulted the value of each crop enterprises tells which production decision allow to make the highest return, taking costs into considerations. As always, it is not wise to overemphasize the usefulness and accuracy of any single measure. The rates of return analysis on total variable cost for those treatments were evaluated. The rate of return analysis result indicated that Bylaton and Mancozeb has high rate of return than other alternative while Redomil has the rate of return value below the control treatment (Table 6).

Table 6: Rate of return analysis.

Usually no single practice will control faba bean gall disease, when different approaches are combined, losses will be minimized. Consequently sustainable disease management has to be focused on a system approach against this disease by suppressing the pathogens before it reaches to economic threshold level. Such a system approach should incorporate various components like selection of variety, crop rotation, field sanitation and time of planting. Thus by manipulation of different integrated disease management (IDM) approaches, it is possible to minimize the risk of the disease. However the success would depend largely on an effective diseases monitoring system, frequent communication among the various disciplines involved in program and active link between research scientists, extension group and farmers.

Conclusion and Recommendation

The primary aim of this experiment was to select the effective fungicide to control faba bean gall. Among treatments the highest disease score were recorded in control, Thiram and Apron star plots in 2013. The highest yield was also recorded in Bayleton and mancozeb sprayed plots respectively. In 2014 the disease prevalence and severity was similar to 2013. Maximum disease score were recorded on Control followed by Thiram and Apron star seed dressing plots. Minimum disease score were also recorded in Baylaton and Ridomil gold sprayed plots. There was a significant difference between biomass yield and grain yield. The highest grain yield was recorded in Baylaton sprayed plot and followed by Ridomil gold and Mancozeb respectively. There was no significant difference between plots in plant height, pod per plant, seed per pot and seed per plant in both years. Seed treatment fungicides were not effective. Even foliar spray fungicides were also less effective except Bayleton.

Usually no single practice will control faba bean gall disease, when different approaches are combined, losses will be minimized. Consequently sustainable disease management has to be focused on a system approach against this disease by suppressing the pathogens before it reaches to economic threshold level. Such a system approach should incorporate various components like selection of variety, crop rotation, field sanitation and time of planting. Thus by manipulation of different integrated disease management (IDM) approaches, it is possible to minimize the risk of the disease. However the success would depend largely on an effective diseases monitoring system, frequent communication among the various disciplines involved in program and active link between research scientists, extension group and farmers.

Future Directions

The study gives clues about faba bean gall disease management with different fungicides, time of application, and different efficacy of fungicides to control the disease. However, testing this fungicides, current rate and frequency may not be enough to recommend full control package, but this information may lead to start further research direction in the area. Then further disease management studies have to be conducted in the area. Moreover efforts should be focused on applying cultural practice and different disease management activities to minimize the pathogen inoculums level in the field. The epidemiology study, environmentally safe and affordable fungicides should be further studied.

Acknowledgements

The author would like to acknowledge, Debre Birhan Agricultural Research Center and ICARDA ADA for technical and financial support during the execution of the experiments in the field.

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