Survey on Nigerian Castor Germplasm for Potential Resistant  Genotypes to Cercospora Leaf Spot

Fungal diseases cause a lot of economic damage in castor and in some instances; it is a limiting factor to commercial cultivation of the crop. In the present study, survey on castor germplasm for sources of resistant genes to Cercospora leaf spot was carried out at National Cereals Research Institute Badeggi, Nigeria. The genotypes were grown in a resolvable incomplete block design with three replications. The results obtained revealed high variability of host resistance among the genotypes. Percentage disease incidence ranged between 16.67% and 100%. A range between 1.43 score and 4.17 scores with average score of 2.89 were recorded for disease severity among the genotypes. Highest (95.92%) and lowest (13.03%) damage index were observed in the genotypes Acc. 059 and Acc. 022 respectively. The Principal component (PC) 1 to 4 explained 100% of the variability in the germplasm. PC1 explained 69.72% of the variability with the major contributory parameters being the disease incidence, severity and damage index. Significant negative correlations were recorded between the seed yield and all the three disease indices. The result of cluster analysis revealed six cluster groups among the germplasm with cluster membership ranging between 4 and 40 members. The cluster I contained members (Acc. 002, Acc. 017, Acc. 022, Acc. 026, Acc. 027, Acc. 048 and Acc. 061) with low average disease incidence, severity and damage index. The results reported here could serve as a basis for further screening of the potential resistant genotypes under controlled condition to develop resistant lines.

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Compatibility of Mancozeb 75 WP with some plant extracts in the integrated management of Cercospora leaf spot disease of okra (Abelmoschus esculentus (L.) Moench)

Ghana Journal of Agricultural Science ◽

10.4314/gjas.v55i2.3 ◽

2020 ◽

Vol 55 (2) ◽

pp. 26-38

Author(s):

V.O. Dania ◽

N. E. Sam

Keyword(s):

Leaf Spot ◽

Sandy Loam ◽

Integrated Management ◽

Disease Incidence ◽

Block Design ◽

Foliar Spray ◽

Leaf Spot Disease ◽

Syzygium Aromaticum ◽

Cercospora Leaf Spot ◽

Combined Application

The use of synthetic mancozeb fungicide has not been effective in the control of okra leaf spot (Pseudocercospora abelmoschi) disease amidst critical issues of environmental concerns. Therefore, this study evaluated the compatibility of mancozeb 75 WP with some botanicals in the integrated management of the disease. Laboratory assay was a 3×4×2 factorial laid out in a completely randomized design with three replications, while the field experiment was a randomized complete block design with 14 treatments. Four extract concentrations, 15, 30, 45 and 50% w/v and 0.5 g/l Mancozeb 75 WP were evaluated. The application of Syzygium aromaticum extract at 50% w/v concentration had the highest mycelial growth reduction of 71.89% of the pathogen. The soil textural class was sandy loam and treatments effect on okra growth indices did not differ significantly (p>0.05). The highest pod yield of 15.48 t/ha-1 was obtained in treatment inoculated with P. abelmoschi. but treated with a combination of S. aromaticum and Mancozeb. The same treatment had the lowest disease incidence of 4.01%, while combined application of C. papaya, S. aromaticum and Mancozeb recorded significantly (p<0.05) lower disease severity among inoculated plants. Therefore, this combination is recommended as foliar spray on okra in place of Mancozeb.

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Evaluation Of Different Concentrations Of Mancob M For The Control Of Cercospora Leaf Spot (Cercospora Sesami Zimm) On Some Sesame Varieties In Yola, Nigeria

Journal of Agriculture and Horticulture Research ◽

10.33140/jahr.02.01.06 ◽

2019 ◽

Vol 2 (1) ◽

Keyword(s):

Field Experiment ◽

Laboratory Experiment ◽

Leaf Spot ◽

Disease Incidence ◽

Block Design ◽

Mean Value ◽

Cercospora Leaf Spot ◽

Plot Size ◽

Randomized Complete Block Design ◽

Disease Parameters

Diseases pose serious constraints to Sesame production in producing areas. Cercospora leaf spot (Cercospora sesami Zimm) has been identified as one of the most prevalent diseases which is to be controlled by Mancob M fungicide. The field experiment was carried out using a Randomized Complete Block Design and was replicated three times on a plot size of 4m x 5m with four sesame varieties and three Mancob-M fungicide levels (0, 2 and 4g) to give a total of twelve treatments. The laboratory experiment involved isolation of the pathogens from diseased leaves with symptoms of Cercospora leaf spot which was identified as Cercospora sesami. Data collected includes growth and disease parameters. The result revealed that 4g Mancob M recorded the lowest mean value for disease incidence and severity at 8WAS which was 90.30% and 35.60% respectively, while the control (0g) recorded the highest mean value for disease incidence and severity at 90.30% and 59.80% respectively. Ex-sudan recorded the lowest value of 720 kg/ha while NCRIBEN 03 recorded the highest yield of 834 kg/ha-1. For the concentrations, 2g recorded a higher yield of 843 kg/ha-1 followed by 0g which recorded 765 kg/ha-1. Variety E8 has a higher resistance to the disease while NCRIBEN 03 tends to be more susceptible but gave a higher yield. It therefore implies that variety E8 which showed higher resistance to the disease can be merged with NCRIBEN 03 (through hybridization) to produce a much better variety.

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Screening of French Bean (Phaseolus vulgaris L.) Genotypes against Alternaria Leaf Spot Caused by (Alternaria alternata) under Dryland Conditions of Kashmir

International Journal of Plant & Soil Science ◽

10.9734/ijpss/2021/v33i2330715 ◽

2021 ◽

pp. 25-30

Author(s):

Sabiya Bashir ◽

Mohammad Najeeb Mughal ◽

Zahida Rashid ◽

Shabeena Majid ◽

Sabeena Naseer ◽

...

Keyword(s):

Alternaria Alternata ◽

Leaf Spot ◽

Disease Incidence ◽

French Bean ◽

Phaseolus Vulgaris L ◽

Dryland Agriculture ◽

Disease Reaction ◽

The Mean ◽

Selection For ◽

Resistant Genotypes

Sixty-three genotypes of french bean was screened against leaf spot (Alternaria alternata) in sick plots at Research Farm of Dryland Agriculture Research Srinagar, Rangreth during Kharif 2018 and 2019. The highest mean disease incidence ranged from 0.00 to 85.00 per cent with the mean disease intensity ranged from 0.00 to 53.26 per cent .One genotype namely ‘Local Pulwama’ was highly susceptible in their disease reaction. Among the screened germplasm, ‘Highly Resistant’ genotypes was SKU-R-601, SKUA-R-105, SKU-R-927, DARS-25, DARS-66, DARS-R-615, while as ‘Susceptible’ genotypes was DARS-8, DARS-12, DARS-11, SKUAST-R-155, SKU-R-928, DARS-7, DARS-R-4, Bhaderwah (L), Local Kupwara black and Raj Jawala. Local Pulwama was found to be a highly susceptible (HS) genotype. Twenty nine genotypes namely., DARS-16, DARS-9, DARS-54, DARS-39, VL-125, DARS-63, ENTO-504, SKUAST-204,SKU-R-925, DARS-60, DARS-109, DARS-43, DARS-44, SKU-R-23, DARS-4, DARS-74, SKU-R-105, DARS-40, DARS-23, DARS-18, SKU-R-71, WB-341, SKU-R-605, Uri local, Shopian (L), SKU-R-23, DARS-71, SSGB-729, DARS-R-19 showed resistant reaction to disease. The selection for resistance was based on the reaction of varieties on leaves.

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Hybridization between resistant and susceptible fenugreek accessions and evaluation of Cercospora leaf spot resistance in segregating generations

Canadian Journal of Plant Science ◽

10.1139/cjps-2018-0223 ◽

2020 ◽

Vol 100 (1) ◽

pp. 1-15

Author(s):

U. Subedi ◽

S. Acharya ◽

S. Chatterton ◽

J. Thomas ◽

D. Friebel

Keyword(s):

Leaf Spot ◽

Dominant Gene ◽

Single Dominant Gene ◽

Narrow Sense ◽

Cercospora Leaf Spot ◽

Narrow Sense Heritability ◽

Trigonella Foenum Graecum ◽

Resistant Genes ◽

Simple Pathway ◽

Resistant Genotypes

Cercospora leaf spot (CLS), caused by Cercospora traversoana, is an important phyto-pathological problem of self-pollinated fenugreek (Trigonella-foenum graecum). Developing resistant genotypes in crop plants has been considered the best option to control diseases for economic, environmental, and social reasons. However, before this can be accomplished, knowledge about the inheritance of disease-resistant genes is necessary for creating high-yielding resistant genotypes. One susceptible fenugreek cultivar, Tristar, and two resistant accessions L3717 and PI138687 were used in two-way crosses using hand emasculation and pollination technique in a greenhouse. F1 plants were grown in a greenhouse and allowed to grow till maturity to produce F2 seeds. Some flowers from F1 plants were crossed back to both resistant and susceptible parents separately to generate backcross (BC1) seeds. Parents, F1, F2, and BC1 populations were grown in the greenhouse using a RCBD with four replications. Plants were inoculated 30 d after sowing with a suspension of C. traversoana at 2 × 105 conidia mL−1. Symptoms were observed and rated on individual plants 25 d after inoculation, and plants were categorized according to susceptible or resistant reactions based on rating scores. Mean disease score was significantly different (p < 0.0001) among generations. In both the cross combinations, results showed CLS resistance in fenugreek (from L3717 and PI138687) was governed by a single dominant gene which is moderately heritable (46% narrow sense heritability). This indicates a relatively simple pathway for transfer of genes to adapted fenugreek cultivars.

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Diversity and occurrence of major diseases of vegetables and fruit crops during spring season at Aanbukhaireni rural municipality of Tanahun district, Nepal

Journal of Agriculture and Natural Resources ◽

10.3126/janr.v2i1.26043 ◽

2019 ◽

Vol 2 (1) ◽

pp. 60-74

Author(s):

Subash Subedi ◽

Sheela Koirala ◽

Saraswati Neupane

Keyword(s):

Leaf Spot ◽

Control Measure ◽

Disease Incidence ◽

Fruit Rot ◽

Spring Season ◽

Cercospora Leaf Spot ◽

Survey Period ◽

Rural Municipality ◽

Vegetables And Fruits ◽

Leaf Curl

A survey has been conducted to assess the diversity and occurrence of major vegetables and fruits cultivated in Aanbukhaireni rural municipality of Tanahun district, Nepal during spring season of 2019.The surveyed areas were Satrasayaphant, Baradiphant and Dumridanda villages of ward no 1, Yeklephant, Markichowk and Pateni villages of ward no2 , Gaadapani village of ward no 3, Saakhar village of ward no 4 and Ghummaune village of ward no. 5. The surveyed area consists of upper tropical and sub tropical climate. The total no of farmers field selected for the survey was 34, 32, 24, 17 and 21 from ward no 1,2,3,4 and 5 respectively.The major vegetables cultivated during survey period in the surveyed area were bean, bitter-gourd, brinjal, chilli, cowpea, cucumber, okra, pumpkin, sponge-gourd, tomato, snake-gourd and bottle-gourd. Similarly, the fruits found in the region were banana, papaya, grapes, mango, litchi, peach, guava, lemon, mandarin orange etc. The major diseases of vegetables noticed were early blight, late blight, cercospora leaf spot, powdery mildew, downey mildew, fruit rot, bacterial wilt, bacterial spot, leaf curl and mosaic. In case of fruits, sigatoka leaf spot, panama wilt, black rot, algal leaf spot, canker, root rot, foot rot, sooty mold, red rust, anthracnose, rust, mosaic, alternaria leaf spot, downey mildew and leaf curl were the major diseases. The higher disease incidence (70%) and severity (48%) in vegetables were recorded in ward no 2 where as the lower incidence (45.2%) and severity (37.71%) were found in ward no 4. Similarly, the higher fruit disease incidence (70.24%) and severity (51.27%) in ward no 1 followed by ward no 2 with disease incidence and severity of 66.79% and 45.14% respectively. The reasons for those results are low educational level, lack of best bet technology, no proper irrigation and fertilizer, unavailability of pesticides for controlling the diseases. This study will be useful to identify the major diseases of vegetables and fruits of terai and inner terai region of Nepal and applying control measure, looking for the best possible solutions.

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Binucleate Rhizoctonia on Tobacco in Zimbabwe

Plant Disease ◽

10.1094/pdis.1998.82.2.263a ◽

1998 ◽

Vol 82 (2) ◽

pp. 263-263 ◽

Cited By ~ 2

Author(s):

A. J. Masuka

Keyword(s):

Leaf Spot ◽

Rating Scale ◽

Disease Incidence ◽

Block Design ◽

Stem Rot ◽

Damping Off ◽

Binucleate Rhizoctonia ◽

Tobacco Seedlings ◽

Disease Rating ◽

Causal Pathogen

Rhizoctonia solani Kühn (teleomorph Thanatephorus cucumeris (A. B. Frank) Donk) anastomosis groups AG 4 and AG 3 cause, respectively, widespread stem rot and leaf spot diseases of tobacco in Zimbabwe (2). Stem rot leads to substantial field losses, necessitating routine chemical and biological control (1). A recent increase in reports on Rhizoctonia-induced damping-off in tobacco seedlings and lodging of mature field plants prompted detailed studies on the causal pathogen. Nuclear fluorescence microscopy studies of 83 isolates from diseased tobacco revealed the presence of binucleate isolates. The isolates were collected in 1981 (1 isolate), 1990 (1 isolate), 1996 (3 isolates), and 1997 (1 isolate) and caused damping-off in seedlings (2 isolates) and stem rot and lodging in field tobacco (4 isolates). We confirmed that all binucleate isolates contained only two nuclei per cell. There was variability in the number of nuclei among the multinucleate stem rot (mean 4.2, SE 0.265) and leaf spot (mean 7.5, SE 0.259) isolates. Two tested binucleate Rhizoctonia isolates were pathogenic to 7-week-old tobacco seedlings (cv. Kutsaga 35) in a greenhouse experiment, laid out as a randomized complete block design. Uninoculated healthy plants served as control. Based on a disease rating scale of 1 to 5 (1 = no disease and 5 = >50% stem damage), overall disease incidence was 88.9% 5 days after inoculation with macerated mycelium at the rate of 3.60 × 105 CFU per seedling, applied around the stem base. Over 50% of inoculated seedlings were rated in disease categories 4 and 5. Binucleate Rhizoctonia were consistently isolated from infected plants. A country-wide survey is being conducted to determine the incidence, distribution and severity of diseases caused by binucleate Rhizoctonia on tobacco in Zimbabwe. References: (1) J. S. Cole and Z. Zvenyika. Plant Pathol. 37:271, 1988. (2) S. I. Mpofu and A. M. Julian. J. Phytopathol. 140: 367, 1994.

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Effective Plant Ages for Screening for Field Resistance to Alternaria Leaf Spot (Caused by Alternaria spp.) under Natural Infection in Jerusalem artichoke (Helianthus tuberosus L.)

Agronomy ◽

10.3390/agronomy9110754 ◽

2019 ◽

Vol 9 (11) ◽

pp. 754 ◽

Cited By ~ 1

Author(s):

Wanalai Viriyasuthee ◽

Suwita Saepaisan ◽

Weerasak Saksirirat ◽

Mark L. Gleason ◽

Ruey Shyang Chen ◽

...

Keyword(s):

Leaf Spot ◽

Disease Incidence ◽

Natural Infection ◽

Block Design ◽

Jerusalem Artichoke ◽

Plant Age ◽

Growth Stages ◽

Alternaria Leaf Spot ◽

Progress Curve ◽

The Impact

Host plant resistance has proven to be effective for controlling Alternaria leaf spot on Jerusalem artichoke (JA), but efficient screening techniques have not been developed yet. The objective of this study is to estimate the relationship between disease resistance parameters of JA as a function of plant age. Six JA varieties and three plant ages at the time of inoculation (20, 40 and 60 days after transplanting) (DAT) are evaluated in a factorial experiment in randomized complete block design (RCBD) with four replications. Disease incidence (DI) and severity (DS) are estimated, from which area under the disease progress curve (AUDPC) was calculated. Disease parameters are positively and significantly correlated for plant ages of 40 and 60 DAT. Based on our results, screening of JA at 40 DAT for resistance to Alternaria leaf spot is recommended. Knowledge of the impact of plant age on resistance to key diseases can help breeders to accelerate breeding programs so superior genotypes can be identified before reproductive growth stages.

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Diagnosis and prescription for Cercospora leaf spot of chilli

Journal of the Bangladesh Agricultural University ◽

10.3329/jbau.v13i2.28779 ◽

2016 ◽

Vol 13 (2) ◽

pp. 191-196

Author(s):

MS Islam ◽

K Fatema ◽

KMB Alam ◽

MB Meah

Keyword(s):

Leaf Spot ◽

Plant Disease ◽

Disease Incidence ◽

Cost Ratio ◽

Cercospora Leaf Spot ◽

Benefit Cost Ratio ◽

Benefit Cost

The experiments were carried out during 2009 to 2013 on diagnosis and prescriptions for management of Cercospora leaf spot of chilli. The studies were undertaken in 250 growers field of five upazillas viz. Mymensingh sadar, Kushtia sadar, Kumarkhali, Chandina and Sher-e-Bangla Nagar. The highest disease incidence (38.6%) and severity (17.4%) of Cercospora leaf spot of chilli was recorded. Cercospora capsici produced leaf spot of chilli. The prescription given by Plant Disease Diagnostic Clinic (PDDC) was effective in the farmers field against the disease. Cercospora leaf spot of chilli is the most important diseases of spices in Bangladesh as the diseases significantly reduce the quality and yield. Prescription was Bavistin-50 DF @ 1g/l sprayed 4 times at 15 days interval for management of Cercospora leaf spot of chilli. The practices reduced the incidence by 72.82%, severity by 65.60%. The yield increased by 35.11%. Benefit cost ratio (BCR) was 3.34.J. Bangladesh Agril. Univ. 13(2): 191-196, December 2015

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Effect of Production System and Pruning on Temporal Development of Cercospora depazeoides and on Berry Yield in Black Elderberry Orchards

Plant Disease ◽

10.1094/pdis-93-6-0625 ◽

2009 ◽

Vol 93 (6) ◽

pp. 625-631 ◽

Cited By ~ 1

Author(s):

I. J. Holb ◽

J. M. Gáll ◽

B. Fodor

Keyword(s):

Leaf Spot ◽

Production Systems ◽

Disease Incidence ◽

Organic Production ◽

Integrated System ◽

Disease Development ◽

Temporal Development ◽

Cercospora Leaf Spot ◽

Organic System ◽

Disease Progress

In a 2-year study, the temporal development of Cercospora leaf spot (Cercospora depazeoides) and berry yield were evaluated in two production systems (integrated and organic) and in two winter pruning treatments (trees pruned to four and eight scaffolds) in two black elderberry (Sambucus nigra) orchards in Hungary. Under organic production, leaf spot onset occurred 2 to 4 weeks earlier (mid- and late July) in both years and both orchards compared with the integrated program. Disease then continuously progressed until the final assessment date (late September) in both years, reaching a maximum final disease incidence of 15.9% in the integrated system and of 38.2% in the organic system. In general, disease progress after late August was greater on trees pruned to eight scaffolds than on trees pruned to four scaffolds in both production systems. Both final disease incidence and area under the disease progress curves (AUDPC) were significantly lower (P < 0.001) in the integrated treatments compared with organic ones. Across all treatments, both disease measures were significantly (P < 0.05) lower on trees pruned to four scaffolds compared with trees pruned to eight scaffolds. However, when the effect of pruning on final disease incidence and AUDPC was analyzed separately for integrated and organic systems, pruning caused uniformly significant differences in disease development only for the organic system. Berry yield was significantly higher (P < 0.05) in the integrated system compared with the organic system, but pruning showed no significant effect on yield. Overall, pruning to four scaffolds resulted in consistently lower disease development in organic production compared to integrated. Thus, winter pruning may be useful as a Cercospora leaf spot management practice in organic elderberry orchards.

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Development of a Sequential Sampling Plan using Spatial Attributes of Cercospora Leaf Spot Epidemics of Table Beet in New York

Plant Disease ◽

10.1094/pdis-07-20-1619-re ◽

2021 ◽

Author(s):

Daniel Winter Heck ◽

Julie R Kikkert ◽

Linda Hanson ◽

Sarah Jane Pethybridge

Keyword(s):

New York ◽

Leaf Spot ◽

Disease Incidence ◽

Sequential Sampling ◽

Sampling Plan ◽

Classification Models ◽

Cercospora Leaf Spot ◽

Sample Number ◽

Sequential Sampling Plan ◽

True Value

Sampling strategies that effectively assess disease intensity in the field are important to underpin management decisions. To develop a sequential sampling plan for the incidence of Cercospora leaf spot (CLS), caused by Cercospora beticola, 31 table beet fields were assessed in New York. Assessments of CLS incidence were performed in six leaves arbitrarily selected in 51 sampling locations along each of the three to six linear transects per field. Spatial pattern analyses were performed, and results were used to develop sequential sampling estimation and classification models. CLS incidence (p) ranged from 0.13 to 0.92 with a median of 0.31, and beta-binomial distribution, which is reflective of aggregation, best described the spatial patterns observed. Aggregation was commonly detected (>95%) by methods using the point-process approach, runs analyses, and autocorrelation up to the fourth spatial lag. For SADIE, 45% of the datasets were classified as a random pattern. In the sequential sampling estimation and classification models, disease units are sampled until a prespecified target is achieved. For estimation, the goal was sampling CLS incidence with a preselected coefficient of variation (C). Achieving the C = 0.1 was challenging with less than 51 sampling units, and only observed on datasets with an incidence above 0.3. Reducing the level of precision, i.e. increasing C to 0.2, allowed the preselected C be achieved with a lower number of sampling units and with an estimated incidence (p̂) close to the true value of p. For classification, the goal was to classify the datasets above or below prespecified thresholds (pt) used for CLS management. The average sample number (ASN) was determined by Monte Carlo simulations, and was between 20 and 45 at disease incidence values close to pt, and approximately 11 when far from pt. Correct decisions occurred in over 76% of the validation datasets. Results indicated these sequential sampling plans can be used to effectively assess CLS incidence in table beet fields.

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