Chocolate Spot Research Articles

Evaluation of endod (Phytolacca dodecandra L.) extracts against Botrytis fabae, a causative agent of chocolate spot disease of Vicia faba

The use of botanicals to control phytopathogens of crops is an alternative to the use of synthetic fungicides. The objective of this study was to evaluate the in vitro growth inhibitory effect of P...

Association of Chocolate Spot and Faba Bean Rust Epidemics with Climate Change Resilient Cultural Practices in Bale Highlands, Ethiopia

Field survey was conducted in south eastern Ethiopia to determine the disease intensity of chocolate spot and rust and to investigate the association of disease intensity (incidence and severity) with environmental factors and crop cultural practices. A total of 280 faba bean fields were surveyed in eight districts, and type of cropping system, weed management practices, crop growth stage, previous crop in the field, and sowing date were recorded. The associations of disease intensity with independent variables were evaluated using logistic regression model. Mean disease incidence of chocolate spot varied from 70.9 to 93.2% in most fields while percentage severity index (PSI) ranged from 10.5 to 47.1%. In a reduced multiple variable model, chocolate PSI ≤ 30% showed high probability of association with mixed cropping system, good weed management practices, late planting, and when faba bean was rotated with vegetables and cereals. The mean disease incidence of faba bean rust was varied from 23.6 to 78.2%, while the mean PSI of rust was varied from 4.8 to 37.9%. In Gasera, Dinsho, and Agarfa districts, poor weed management practices, fields planted in the month of July, and when previous crop was legume had a high probability of association to (>20) rust PSI in a multiple variable reduced model. In contrast, soil types, fertilizer applied, and fungicides sprayed were not associated with disease intensity. The present study has identified cropping system, planting date, previous crop, district, and weed management practices as important variables that influence faba bean chocolate spot and rust epidemics in diversified fields. Therefore, proper weeding management practices, late planting, crop rotation habit, and other related farm practices should be carried out to reduce chocolate spot and rust impact until resistant faba bean genotypes are developed and distributed to the area.

English

Field experiment was conducted at Chencha Woreda with the objective of evaluating faba bean varieties for better yield and chocolate spot disease resistance during 2015 main cropping season. Ten improved faba bean varieties and two local controls were evaluated in randomized complete block design (RCBD) with three replications. Field performances of varieties were evaluated for grain yield and yield parameters on sampled plant. Chocolate spot disease severity was recorded following 1 to 9 disease scale and used for area under disease progress curve (AUDPC) calculation. There was significant (P < 0.05) difference among the varieties for yield and resistance to chocolate spot disease. Higher yield was recorded in Moti, Gora and Wolki varieties while low yield was recorded from Hachalu and Degaga. Maximum chocolate spot severity and AUDPC were recorded on Baela, Degaga, Gora and Gebelcho varieties while minimum disease severity and AUDPC were recorded from Tumsa, Moti, Hachalu and CS-20DK varieties with a mean severity of 29.63, 24.69, 25.93 and 25.93%, respectively. Moti, CS-20DK, Hachalu and Tumsa varieties showed moderately resistant to chocolate spot disease severity while Dosha was moderately susceptible varieties. From the result it could be concluded and recommended that varieties Moti, Gora and Tumsa are promising at high lands of Chencha, and may used them in larger plot for identification of adaptable variety. Key words: Faba bean, varieties, yield, disease severity, chocolate spot.

DISEASES OF BROAD BEANS CAUSED BY MICROSCOPIC FUNGI

The unique biochemical composition of broad bean seeds (Vicia faba L. var. major Harz) makes them a promising vegetable crop. The quantity and quality of the yield of beans depends to a large extent on the mycoses caused by microscopic fungi. The aim of the work was to study the diseases of broad beans caused by microscopic fungi in the soil and climatic conditions of the South Central zone of the region. At the Botanical garden BelSU (Belgorod) on a natural infectious background were grown and studied of different broad beans varieties Belarusian, Velena, Russian black, Aquadulche. In some years, the prevalence of Alternaria leaf spot was 8-57%, but the lack of yield did not exceed 12%. Fusarium wilt was spread to 90%, with a disease development index of up to 82% and a loss of yield of 16-64%. In cases of mixed infection (fusariosis + alternariosis, fusariosis + chocolate spot) on plants in the budding-flowering phase (before and after the phase of fruit formation), the destruction of affected plants was noted. The spread of mixed infection was prevented by dry weather during the development of plant generative organs. The development of bean leaf and pod spot, which reduced the productivity by no more than 15%, contributed to the dry period of bean growth. Chocolate spot (not marked on varieties Russian black and Velena) and blackish spotting were noted not on all grades and not annually, reducing the yield of beans by 2-10%. In general, over the years of research, the lowest losses of yield from mycoses are noted for the Belarusian.

Genetic variability of faba bean genotypes for chocolate spot (Botrytis fabae) resistance and yield

Faba bean (Vicia faba L.) has high utility as a food and soil fertility improving crop. One of the major fungal pathogens of faba bean is Botrytis fabae, the causative agent of chocolate spot. The disease affects significantly the leaf, stem, pod and seed of faba bean compromise its productivity in the smallholder farming sector. Nonetheless, there are limited resistant/tolerant faba bean varieties available and disease control technology options. Therefore, it was prudent to evaluate faba bean landraces for chocolate spot resistance. Fifty landraces together with ten improved varieties were evaluated both in the field and in the greenhouse under natural and artificial inoculation with previously selected aggressive Botrytis fabae isolate (Iso-016) from West Gojjam, in Ethiopia. There were highly significant differences (p < 0.001) among the landraces for reaction to the disease and agronomic traits. Significant positive correlation was recorded between reaction of genotypes in the field and greenhouse disease data. The overall mean disease epidemics varied from 92.5 to 697.5 for the area under disease progress curve (AUDPC). The highest level of resistance was found in the ICARDA lines, ILB-4726, ILB-938 and BPL-710. Of all 18 landrace collections displayed significantly lower disease reaction than the susceptible check. However the resistance was moderate. The selected eighteen landraces will be recommended for use in breeding for chocolate resistance. Overall, resistance was highly heritable, suggesting that phenotypic selection can be exploited to improve chocolate spot resistance in faba bean varieties.

Combination between Benzothiadiazole and Trichoderma Viride to Control Chocolate Spot Disease of Faba Bean and Their Effects on some Biochemical Characters

Combination between Benzothiadiazole and Trichoderma Viride to Control Chocolate Spot Disease of Faba Bean and Their Effects on some Biochemical Characters

Integrated management of faba bean chocolate spot caused by Botrytis fabae in Gondar, Ethiopia

Integrated management of faba bean chocolate spot (Botrytis fabae Sard.) was studied using moderately tolerant variety, “Hachalu” and the local cultivar at Chilga district during 2016 main cropping season. The objective was to evaluate effect of host resistance, intercropping and fungicide applications on epidemics of faba bean chocolate spot, yield and yield components of faba bean, and sole and intercrop systems productivity. The experiment was randomised complete block design in a factorial combination of two faba bean cultivars, two cropping systems (Hachalu- and local-barley intercropping in 2:1 ratio) and four levels of fungicide (Chlorothalonil) spray and integration in three replications of faba bean and barley, respectively. Cultivars and spray intervals significantly (p < .01) affected the seed yield while cultivars alone had significant variation (p < .01) on 100-seed weight as a main effect. Therefore, 21-days fungicide spray intervals integrated with Hachalu sole and Hachalu-barley intercropping may be considered for chocolate spot management.

On-farm demonstration of fungicide for the control of chocolate spot (Botrytis fabae L.) on faba bean in Bale zone, Ethiopia

Faba bean ( Vicia faba L.) is one of the most important food legumes in the world and in Bale-highlands as well. The experiment was executed for one year at Goba and Dinsho districts with the objectives of demonstrating different fungicide for the control of chocolate spot on faba bean and to give awareness on the use and effectiveness of the fungicide against chocolate spot on faba bean. The experiment was conducted using one faba bean varieties; Moti and two fungicide Mancozeb 80% (2.5 kg/ha) and Odeon 825 WG (2.5 kg/ha). The highest mean chocolate spot severity index recorded was 55% on unsprayed plot and the minimum mean chocolate spot severity index was recorded on Odeon 825 WG sprayed plot 27.5% severity at Goba district. Mancozeb 80% WP sprayed plots gave higher yield 2680 kg/ha and 2490 kg/ha at both locations as compared to Odeon 825 WG and unsprayed plots. Maximum percent of seed yield was increased over check by Mancozeb 80% WP 34.33% at Goba. Mancozeb 80% WP sprayed plot provided the highest gross returns (birr 40,200/ha) and 37,350/ha at Goba and Dinsho, respectively. The lowest gross return was computed from untreated check at both locations. The plot sprayed with Mancozeb 80% WP gave the maximum net return and also gave the highest benefit cost ratio at both locations. Farmers and others stakeholders can use these fungicides by integrating with other option to maximize their production and productivity as well as quality.

Integrated Management of Faba Bean Chocolate Spot (Botrytis Fabae Sard.) Through Host Resistance, Intercropping and Fungicide Applications in Arsi, Ethiopia

Integrated Management of Faba Bean Chocolate Spot (Botrytis Fabae Sard.) Through Host Resistance, Intercropping and Fungicide Applications in Arsi, Ethiopia

Trichoderma harzianum and some antioxidants for suppressing faba bean chocolate spot incidence under natural field infection

Chocolate spot is one of the most important diseases affecting faba bean in Egypt. The field experiment was conducted for two cropping seasons with the objective of evaluating the efficacy of 'Trichoderma harzianum' and five antioxidant agents, i.e. Vitamin C, Vitamin E, Selenium, VitaMax Plus against Chocolate spot disease incidence and severity under field conditions. Field study was performed during two successive growing seasons (2015/2016 and 2016/2017) using the bioagent T. harzianum and antioxidants individually or in combinations. All treatments were applied as faba bean foliar spray three times with 15 days interval starting at the beginning of flowering stage. Percentages of disease incidence and severity were measured for each growing season and their mean was calculated. Results showed that all applied treatments could reduce chocolate spot disease incidence at a range of 66.6 to 92.2% compared to the fungicide Diathane M45 (39.0%). Meanwhile, disease severity followed similar trend. It was reduced by a range of 38.7 up to 75.1% and 20.9% relatively to control at applied treatments of antioxidants individually or combined with 'T. harzianum' and the fungicide, respectively. Combined treatments showed that when 'T. harzianum' combined with either one or all of the used antioxidants, they had superior effect for reducing disease incidence and severity on faba bean plants compared to fungicide and the control. Meanwhile, all of the antioxidants in combination showed lesser suppression effect on disease incidence and severity than individual treatment. The present findings demonstrate that bio-agent 'T. harzianum' integrated with antioxidant as foliar spray treatment can be recommended for the future use in a commercial scale for effective management of Chocolate spot on faba bean.

Yield loss of faba bean (Vicia faba L.) due to chocolate spot (Botrytis fabae Sard.) in Sinana, Southeastern Oromia

Field experiment was conducted at Sinana Agricultural Research Center in the 2014 main cropping season with the objective to assess yield losses caused by chocolate spot ( Botrytis fabae ) of faba bean varieties. The highest number of days to physiological maturity was recorded on the variety Shalo (141.6 days) and lowest in the variety Mosisa (138.5 days). The maximum biomass on hectare basis (6.6t/ha) was obtained from plot sprayed at weekly interval. The maximum relative grain yield loss were recorded from the varieties of Mosisa and local, 47.8% and 46.7% on unsprayed plots, respectively. Losses in hundred seed weight greater on the variety local than others, this variety had maximum hundreds seed weight loss of 16% when it was protected against the diseases. The local variety shows the maximum biomass loss compared to other varieties under unsprayed plots. This variety has a biomass loss of 33% under unsprayed plots. The highest marginal benefit (32022.9 ETB/ha) was obtained from variety Mosisa sprayed at weekly intervals and highest (233.7 ETB) marginal rate of return was obtained also from this variety when treated at weekly intervals.

Evaluation of Faba Bean Varieties against Chocolate Spot (Botrytis fabae Sard) Disease at Farta, South Gondar, Ethiopia

Faba bean (Vicia faba L.) is an important food legume crop in Ethiopia, and its production and productivity are decreased by biotic and abiotic stresses. Among the biotic stresses, chocolate spot disease is the major and the most destructive disease in faba bean-growing areas. A field experiment was conducted at Farta to evaluate the genetic variation of faba bean varieties to chocolate spot, and for yield and yield components during the 2014 and 2015 main cropping seasons. A total of 13 improved faba bean varieties and one local check were sowed in three replications using a randomized complete block design. The chocolate spot disease incidence and severity were taken four times in 10-day intervals. There was a significant difference (P < 0.05) among faba bean varieties on disease incidence and severity. The disease incidence was lower on varieties Obse and Moti. The severity of chocolate spot was lower on varieties Obse, Tumsa, and Degaga. Varieties Obse, Degaga, and Tumsa significantly reduced the severity of chocolate spot disease by 8.89, 6.85, and 5.91%, respectively, over Bulga 70 and Adet-Hana. Varieties Obse, Degaga, and Tumsa significantly reduced the AUDPC of chocolate spot disease by the amount of 229.63, 214.81, and 187.96% over variety Bulga 70, respectively. The highest yield (t/ha) was obtained from variety Degaga (1.55) and Tumsa (1.30). Thus, to conclude and recommend that variety Degaga and Tumsa are moderately tolerant or less susceptible to chocolate spot disease than other varieties with a better yield.

English

Field survey was done in North Gondar during 2014/2015 and 2015/2016 cropping seasons with the objective of, assessing the importance of faba bean diseases. Disease severity varied across and within districts. Chocolate spot (Botrytis fabae), gall-forming (Olpidium viciae), rust (Uromyces fabae) and aschochyta blight (Aschochyta fabae) were the most dominate and frequently occurring diseases of faba bean. The highest mean severity of chocolate spot (43%) and rust (36%) were recorded at Takusa district whereas the highest mean severity (42%) of gall-forming disease was recorded at Debark district. The association of independent variables with faba bean disease varied among themselves. Variables such as year, altitude, growth stage of the crop and crop conditions were significantly associated with the chocolate spot, gall-forming, and rust diseases. Chocolate spot, gall-forming, and aschochyta blight diseases severity was higher in surveyed fields with an altitude greater than 2,700 m above sea level (masl). However, rust severity was higher in areas with an elevation below 2,200 m.a.s.l. Among growth stages, the highest disease severity of chocolate spot, rust, and aschochyta blight was recorded on fields during the flowering stage. Therefore, integrated disease management options should be developed for the future for those major diseases of faba bean. Key words: Aschochyta blight, chocolate spot, gall-forming disease, severity, rust.

Botrytis fabae and Bean common mosaic virus (BCMV) are the most common diseases of Faba bean (Vicia faba L.) in TRNC

Surveys were conducted on the fields of faba bean culture in Turkish republic of North Cyprus (TRNC) during 2011-2013 indicated that Botrytis fabae and Bean common mosaic virus (BCMV) are the diseases that cause crop loss at economic level. During the field surveys 117 infected plants that have the symptoms of both diseases were collected from 38 different locations. Symptomatologic, morphologic and classic tests indicated that 96 of the faba bean samples had Chocolate spot disease caused by Botrytis fabae and the conidia lengths have been measured between 12.7-22.4 x 9.4-17.8 microns. Faba bean samples with virus symptoms that were collected from 38 locations. All samples were infected by Bean common mosaic potyvirus (BCMV) serologically (DAS-ELISA). The 850 bp section of BCMV isolates coat protein was increased using RT-PCR method. This section was sequenced directly using ClonJet and characterization was determined. According to Blast obtained from sequences 98% and 96 % resemblances with Mexican and Columbian isolates have been found.

Analysis of genotype × environment interaction and stability for grain yield and chocolate spot (Botrytis fabae) disease resistance in faba bean (Vicia faba)

Analysis of genotype × environment interaction and stability for grain yield and chocolate spot (Botrytis fabae) disease resistance in faba bean (Vicia faba)

Heterosis and path analysis for grain yield and chocolate spot disease resistance in faba bean (Vicia faba L.)

Heterosis and path analysis for grain yield and chocolate spot disease resistance in faba bean (Vicia faba L.)

INTEGRATED MANAGEMENT OF CHOCOLATE SPOT (BOTRYTIS FABAE) DISEASE OF FABA BEAN (VICIA FABA L.) IN ETHIOPIA: A REVIEW

The primary producers of pulses are small-scale farmers with small and dispersed plots under rain-fed conditions with substantially lower yields of less than 0.9 t/ha as compared to the improved faba bean varieties and international yields. There are many biotic and abiotic factors which hampers faba bean production in Ethiopia. From biotic factors chocolate spot (Botrytis fabae Sard.) is the major fungal disease hampering faba bean production in Ethiopia.). It is a highly prevalent and destructive disease, causing yield loss up to 61% on a susceptible and 34% on tolerant faba bean genotypes in the central highlands. But we can manage this economically important disease in manner which comprises all available diseases management methods in combination that is IPM (Integrated Pest management). So, the objective of this review work was to review available integrated pest management option for management of chocolate spot disease of faba bean in Ethiopia. We can control the disease by using different methods from these late sowing of faba bean, mixed cropping of faba bean with cereal crops and mancozeb spray reduced the disease and increased the grain yield and seed weight over sole and mixed cropping with field pea; also cereal mixing with faba bean has advantages over faba bean mixing with field pea. Suppressive effects can be ascribed to a combination of host biomass reduction, altered microclimate and physical barriers to spore dispersal. Also creation of a physical barrier in the form of non-host plants prevents some of the dispersed spores from being deposited on the host tissue by interception. In Ethiopia, study has revealed that the biological control agents for chocolate spot of faba bean and Bacilli are natural residents of faba bean leaves. Additionally recommendation have been given that, further study has to be done to explore the mode of action by bacillus subtilis against fabae.

Management of Chocolate Spot ( Botrytis fabae L. ) on Faba Bean in Bale Highland’s, Ethiopia

Field experiment was conducted at Sinana Agricultural Research Center in the 2014 main cropping season with the objectives wasto study the reaction of faba bean varieties to infection of the chocolate spot and to assess yield losses caused by chocolate spot (Botrytis fabae) of faba bean four varieties. The highest mean final disease severity at (118 DAP) 38.29% was recorded on the main plots of the local variety and lowest mean final disease severity 32.75% was on the main plots of the variety Mosisa. The maximum Area Under the disease progress curves (AUDPC) was calculated on the unsprayed plots of local variety and Walki, which were 1817%-days and 1716.42%- days respectively. On unsprayed plots of variety local chocolate spot development was increasing at a rate of 0.03 units per day. For the variety local, chocolate spot severity index assessed from 90 DAP had significant negative correlation with yield and had highly significant negative correlation with hundred seed weight with coefficient of correlation ranging from(r=-0.67 to r=-0.62, P<0.05 and r–0.71 to r=-0.75, P<0.01) for yield and hundred seed weight, respectively. The linear regression of AUDPC better described the relationships between faba bean yield and disease severity compared to percent severity index for the variety Shallo. The estimate showed that for each unit increase in percent of chocolate spot AUDPC, there was a grain yield loss of 1.19 kg/ha The estimated slope of the regression line obtained for the variety Shallo was -1.19. Based on coefficient of determination (R2) value, the equations explained about 78% of variation in yield due to chocolate spot severity. Maximum relative grain yield losses of 47.8 and 46.7% were recorded due to chocolate spot severity on the varieties Mosisa and Sinana local, respectively.

English

Botrytis fabae incites chocolate spot, one of the most devastating fungal diseases infecting and constraining faba bean cultivation in Ethiopia. Culturing of B. fabae and mass production of its infective conidia has been very difficult for pathological researches on the disease caused by this fungus. Therefore, two in vitro experiments were conducted to evaluate influence of culture media on mycelial growth and sporulation of B. fabae. Ten and six separate media were evaluated for mycelial growth and sporulation, respectively. A 6 mm agar plug of fresh B. fabae culture was inoculated to each medium, arranged in CRD with 4 replications and were incubated at 22°C. Of the media tested, significantly highest (89.40 and 88.15 mm) mycelial growth were recorded on chickpea dextrose agar (CDA) and soybean dextrose agar (SBDA), respectively. Sabouraud dextrose agar supported the lowest (66.40 mm) mycelial growth 7 days after inoculation at 22°C. Significantly excellent conidial formation and spore count were recorded from Chrysanthemum flower dextrose agar (CFDA) medium (1.07 x 106/ml). Potato dextrose agar (PDA) was found inferior both in growth and sporulation of the fungus ad compared to those tested media which exhibited maximum mycelial growth and excellent sporulation. The overall results of this study indicated that cultural characteristics, mycelial growth and sporulation of B. fabae were influenced by media sources, implying that CDA and SBDA were best suited for mycelial growth. CFDA supported maximum sporulation and conidial production as compared to PDA medium. This study might be helpful for studying various aspects of B. fabae and further enhanced by complementing the tested media with different C, N and salt sources to investigate various biological and molecular characteristics of the fungus. Key words: Botrytis fabae, conidial formation, culture media, mycelial growth, spore count.

Study on Prevalence and Importance of Faba Bean Diseases in Sidama and Gedeo Highlands, South Eastern Ethiopia

Ethiopia is the largest producer of Faba bean in world next to China. Faba bean is valuable as the cheap source of protein in most Ethiopian diet. However, the productivity remains far below the crops potential. Disease is the major treat to production in Ethiopia. Survey was conducted in Sidama and Gedeo zone highlands of Ethiopia during the 2016 cropping season to determine the prevalence, incidence and severity of faba bean chocolate spot (Botrytis fabae Sard.), rust (Uromyces viciae-fabae) and ascochyta blight (Ascochyta fabae) in major growing districts, and the influence cultural practices on faba bean disease epidemic. A total of 49 faba bean fields were surveyed in four districts. Sample plants were systematically selected in an “X” fashion. In each field, five plants in 1×1 meter quadrant were sampled for disease assessment. During the survey, altitude, cropping system, planting pattern, crop growth stage and weed management practices were recorded. The overall mean prevalence of faba bean chocolate spot, rust, ascochyta blight were 100%, 58.5%, and 33.8%, respectively. Significant differences among districts were showed with respect to chocolate spot, rust and ascochyta blight incidence and severity. The districts varied in incidence and severity of chocolate spot. The mean incidence of chocolate spot varied from 60.0% in Hulla to 100% in Melga, while severity varied from 37.7% in Dara to 50.0% in Bulle district. The mean incidence of the rust varied from 22.0% in Bulle to 58.3% in Melga while severity varied from 16.6% in Bulle to 42.2% in Dara district. The mean incidence of the ascochyta blight varied from 3.3% Melga to 45.8% in Hulla, while severity varied from 14.8% in Melga to 37.7% in Hulla district. The survey was identified cropping system, growth stage, planting pattern and weed management as important variables that influenced faba bean disease epidemic. The result indicated that mixed cropping system resulted in less chocolate spot severity. Fields having good weed management score showed the lowest incidence and severity of rust as compared to their respective other variable classes. Maximum severity of ascochyta blight recorded in where faba bean was at broadcast. The survey revealed high prevalence and distribution of faba bean chocolate spot, rust, ascochyta blight in the study area and the need for effective and feasible management options to be developed.