Infected Pods Research Articles

The cacao pathogen Moniliophthora roreri (Marasmiaceae) produces rhexolytic thallic conidia and their size is influenced by nuclear condition

Moniliophthora roreri, the causal agent of frosty pod rot of cacao, is a member of the mushroom-forming family Marasmiaceae (Marasmiineae, Agaricales, Basidiomycota). Yet, M. roreri has never been observed to produce a mushroom fruiting body, but rather produces billions of spores on the surface of infected pods. The question of whether these spores are produced via meiosis or mitosis has been the subject of some speculation. However, numerous molecular-based studies have been unable to support a hypothesis of sexual recombination for this fungus. We re-examined sporogenesis and the nuclear condition of hyphae and spores in M. roreri via nuclear staining and spore germination studies. Conidia are produced asexually in a thallic and rhexolytic manner as is true for other Marasmiineae species such as M. perniciosa, Flammulina velutipes and Marasmius puerariae. We also found that hyphal cells as well as spores harbor one or two nuclei, rarely three, that conidium size is influenced by number of nuclei within, and that individual isolates produced consistently and significantly different proportions of binucleate and mononucleate spores regardless of varietal group.

Impact of anthracnose on the yield of soybean subjected to chemical control in the north region of Brazil

ABSTRACT Losses due to soybean anthracnose, caused by Colletotrichum truncatum, have not been systematically quantified in the field, and the efficacy of chemical control of this disease is not known. This study shows an estimate of losses associated with the disease in soybean crops in the north of the country. Two trials with cv. M9144 RR were carried out in commercial fields in Tocantins State in the 2010/2011 and 2011/2012 growing seasons, in randomized blocks, with four replicates. Foliar applications were performed on plants at R1/R2 and R5.2 stages, employing CO2-pressurized equipment and application volume of 200 L ha-1. Nine fungicides and one untreated control were compared, and the disease gradients in the two seasons were obtained. The percentage of infected pods was calculated at the R6 stage. Grain yield ranged from 3,288 to 3,708 kg/ha in the untreated plots in 2010/2011 and 2011/2012, respectively, and from 3,282 to 4,110 kg/ha in the treated plots. In the 2010/2011 season, only azoxystrobin + cyproconazole significantly reduced the disease incidence, compared to untreated control plots, not differing from the remaining treatments. In the 2011/2012 season, there were no significant differences between treated and untreated plots. Highly significant correlations (p < 0.01) were found between yield and soybean anthracnose incidence on pods in both years (r = -0.85). For each 1% increment in the disease incidence, c. 90 kg/ha of soybean grain were lost. The current study determined that significant losses due to anthracnose occur in commercial crops in the north of the country and highlighted the limitation of chemical control as anthracnose management method.

Cultivar resistance offers the first opportunity for effective management of the emerging powdery mildew (Erysiphe cruciferarum) threat to oilseed brassicas in Australia

Powdery mildew of brassicas, caused by Erysiphe cruciferarum, is an emerging threat to oilseed Brassica production in Australia. Resistance to powdery mildew was assessed in 112 current and historic Australian Brassica napus canola cultivars and five cultivars of B. juncea mustard cultivars under controlled environmental conditions. Only 18% of leaf area was infested by the end of the test on the most resistant cultivars, compared with means of up to 70% for the most susceptible cultivars as well as severe stem and pod infection. For B. napus, cultivars with the greatest potential for reducing the impact of powdery mildew in the field were Trooper, Bravo TT, Summit, Tumby, Narendra and Hyola 650TT, all ranked in the 10% of cultivars with the lowest leaf infestation (Area Under The Disease Progress Curve (AUDPC) <537) and with <10% of stem area infested. For B. juncea, the level of leaf infestation was lowest for Sahara CL and Xceed X121 CL (AUDPC 303 and 380 respectively), but the high levels of stem infestation (42% and 28% respectively) in these cultivars may reduce their usefulness in the field. The most resistant cultivars identified can be immediately deployed into regions where powdery mildew is prevalent, providing the canola industry with an immediate and effective option for management of this increasingly troublesome disease.

Integrated management of Ascochyta blight (Didymella fabae) on faba bean under Mediterranean conditions

Integrated disease management options (two sowing dates, three fungicides and 3–6 faba bean genotypes) in managing Ascochyta blight affecting faba bean were evaluated for three cropping seasons (2006/07–2008/09) in northern Syria for their effects on disease parameters, seed infection and dry seed yield. The combined results of the three seasons on disease parameters showed that sowing dates significantly affected final disease severity and area under the disease progress curve (AUDPC); faba bean genotypes significantly affected final disease severity, rate of disease development and AUDPC. The highest AUDPC (255% days) was observed in early than late planted (168% days) faba bean genotypes. The mean AUDPC of faba bean genotypes ranged from 189% days on genotype 1053–1325 to 234% days on ILB-1814. Only faba bean genotypes and fungicides showed significant interactions in affecting final disease severity and AUDPC. Fungicide sprays significantly affected mean percent pod infection and rate of disease development but not mean percent seed infection. Faba bean genotypes showed significant differences in dry seed yield and the yield ranged from 1.7 t ha−1 in cv. Ascot to 2.4 t ha−1 in faba bean genotype 945-105. Improved varieties with Ascochyta blight resistance are not currently released and available for farmers in northern Syria and the integration of early planting (November–December) with one foliar fungicide spray at vegetative stage can help to reduce Ascochyta blight severity, pod and seed infections. Chlorothalonil and azoxystrobin are widely used fungicides to manage Ascochyta blights on food legumes in many countries and one of them could be used depending on their availability and costs to managing faba bean Ascochyta blight in Syria and other Mediterranean type environments.

Infection of canola pods by Leptosphaeria maculans and subsequent seed contamination

Blackleg disease caused by the pathogen Leptosphaeria maculans is the most devastating disease of canola (Brassica napus, oilseed rape). This disease occurs in all canola-growing regions of the world except China. It has been suggested that L. maculans contaminated seed and admixture (associated plant debris) could lead to a blackleg epidemic in China and as a consequence, restrictions on importations into China were placed on canola seed from Australia and Canada in 2009. We show that canola pods infected by L. maculans can lead to seed contamination, and resultant seedling infection, which then leads to cankering in adult plants. The fungus can sexually reproduce over summer on stubble derived from these plants. Airborne sexual spores are then released in the following year– thus completing the life cycle of the fungus from a contaminated seed and providing a potential source for an epidemic, particularly in countries such as China where canola cultivars do not have high levels of resistance to L. maculans. Furthermore, sexual fruiting bodies can also be produced on admixture. The presence of blackleg lesions on canola pods correlated with seed contamination by the blackleg fungus. Viability of L. maculans is reduced on contaminated seed over a twelve month period. Surveying blackleg disease in field trials in Australia showed that the presence and degree of stem cankers did not correlate with the level of pod infection. This suggests that pod lesions are likely to arise as a result of new infection events, rather than the pathogen moving from pre-existing infections (stem cankers) onto the pods. Furthermore, pod infections are likely to be a result of seasonal conditions rather than specific to regions where canola is cropped at a high intensity.

The Isolation and Identification of Soybean Pod and Stem Blight in Taiwan

Phomopsis seed decay (PSD) caused by Diaporthe phaseolorum var. sojae (Lehman) Wehmeyer, Diaporthe phaseolorum (Cooke & Ellis) Sacc. var. caulivora Athow & Caldwell, and Phomopsis longicolla Hobbs reduces quality of soybean (Glycine max (L.) Merr.) seed when it is wet and warm condition during seed maturation period. To study of the PSD in Taiwan in March 2008, three unidentified fungal isolates (isolate1, isolate2 and isolate3) were isolated from soybean stems infected with pod and stem blight which is associated with seed decay. Based on their morphological and genotypic characteristics, three isolates were regarded as Diaporthe phaseolorum var. sojae. For PSD assay, we found that the best condition for the fungal isolates growth was on potato dextrose agar (PDA) media at 24°C temperature for 24 or 15 hr photoperiod. Leaf- stem and pods of soybean were inoculated by an atomizer with two isolates among three isolates to investigate PSD infection. In the result of two inoculation parts with two isolates, there was no significant difference in degree of pod infection and seed infection rate (%) between isolate2 and isolate3, but there was a tendency that pod inoculation than leaf- stem inoculation caused higher level of seed infection. These isolates obtained in this study would be applicable to screening of PSD resistant soybean germplasms in the breeding program.

Dieback of cocoa (Theobroma cacao L.) plant tissues caused by the brown cocoa mirid Sahlbergella singularis Haglund (Hemiptera: Miridae) and associated pathogenic fungi

The brown cocoa mirid,Sahlbergella singularisis the most important insect pest of cocoa for field damage has been classified into three categories that include blast, stagheadedness and mirid pocket. The mirid attack predisposes the cocoa plant to secondary infection by opportunistic pathogenic fungi. This study evaluated the dieback conditions associated with mirid damage due to associated fungi from lesions on pods, twigs and pin punctures. The relationship betweenPhytophthorablack pod infection and mirid infestation in the field was also established. The results indicated that dieback progression from the mirid lesions (8.5 mm) was significantly different (P< 0.05) from that of pin punctures (7.8 mm).Lasiodiplodia theobromaehad the highest proportion of isolates from pods (33%), twigs (47%), and pin punctures (38%).Fusarium decemcellulare(Albonectria rigidiuscula) accounted for 27.8% and 31.6% from pods and twigs; however, it was not recovered from pin punctures. Other isolated pathogens wereAspergillusspecies andRhizoctoniaspecies. There was a significantly strong positive correlation coefficient of 0.74 between the mirid population and the black pod disease infection in the field. The major fruit-bearing season of cocoa witnessed an increase in mirid infestation and blackpod infection. The effect of mirid–pathogenic fungi-associated damage could be ameliorated through effective crop husbandry practices to ensure that cocoa plant tissues are not unduly exposed to biological and mechanical injuries.

INTEGRATED CONTROL OF Etiella zinckenlla INFECTED COWPEA IN UPPER EGYPT AND ITS EFFECT ON PRODUCTIVITY.

Field studies were conducted at Shandweel Agricultural Research Station (Sohag Governorate) to evaluate the integration program which include varietal tolerancy of three cowpea cultivars (Kaha-1, Cream-7 and Dokki-126) against the infestation with E. zinckenella, also, the effect of Trichogramma evanescans, the use Neem extract and Lannate insecticides. The release of egg parasitoid T. evanescans at rat of 30.000 wasps/fed. in cawopea fawned significantly with the Neem in the infested pods and infested seeds. The %infested pods clearly decreased after application of these considered treatments with about 69.21, 75.96 and 75.13% when used Trichogramma wips, but these results in Neem about 57.50, 54.55 and 64.93%, respectively, however, the results were about 72.62, 74.18 and 73.56%, respectively when used Lannate compared with the control, in the first season. Insignificant differences in %infested pods were observed between the three cultivars. No significant differences were found in percent reduction of %infested pods, infested seeds and number of larvae/pods between cowpea plants treated with Trichogramma and those treated with Lannate insecticide. Could be recommended relesease of egg parasitoid T. evanescens to control agents against E. zinckenella. Correlation studies showed highly negative significant among percentage infected pods and seeds traits and each of number of pods/plant, weight of pods/plant, weight of seeds/plant, 100-seeds weight and dry seeds yield/fed., but, it was positive insignificant with number of branches/plant, in the both seasons.

Imaginal and ovicidal effect of some insecticides against Bruchus pisorum L. (Coleoptera: Chrisomelidae)

Abstract Trials were conducted in 2011 and 2012 at the Institute of Forage Crops, Pleven, Bulgaria, in order to study the imaginal and possible ovicidal effect of some insecticides against Bruchus pisorum under field conditions. Treatments with insecticides were started after the appearance of the first pea weevils eggs on pods located on the bottom two nodes. It was found that treatment with acetamiprid; thiacloprid; thiacloprid+deltamethrin; 50 g cypermethrin+480 g chlorpyrifosethyl, 50 g cypermethrin+500 g chlorpyrifosethyl and zeta-cypermethrin resulted in the cessation of additional oviposition on the lower nodes by Bruchus pisorum, due to the toxic effect of the insecticides on the pea weevil. It was found that spraying with acetamiprid and zeta-cypermethrin was the most effective. These insecticides significantly reduced the proportion of infected pods in comparison with the proportion of pods with eggs before the treatment by 30.2 and 27.4% and by 15.8 and 24.0% in 2011 and 2012, respectively. The use of acetamiprid and zeta-cypermethrin was also associated with the lowest percentage of infected seeds (21.7 and 23.6%, respectively), with the lowest percentage of infected seed in infected pods (40.5 and 42.5%, respectively) and the highest weight of 1000 infected seeds (161.94 and 182.04 g, respectively). It was concluded that the management of pea weevils in the crop with acetamiprid and zetacypermethrin can lead to satisfactory results when spray timing is chosen when the first eggs are visible.

Cost effective strategies for the management of Fungal leaf spot of greengram caused byCercospora canescensEll. & Mart. under temperate condition of Jammu and Kashmir

Greengram sown from May-26 to July-5 at 10 days interval in Kashmir manifested variable disease scores. While May-26 sown crop suffered significantly lower leaf spot intensity (25 %) and pod infection (34 %), the following sowings such as June-5, June-15, June, 25 and July-5 suffered 32-47, and 39-64 per cent leaf spot intensity and pod infection, respectively. May-26 sowing supported maximum seed yield (8.2 q/ha) and a proportionate decrease in seed yield of late sowings was recorded with lowest (7 q/ha) obtained in July-5 sown crop. Fungicides were evaluated as seed treatment as well as one or two foliar applications. Seed treatment with carbendazim and captan showed poor results in both disease control and seed yield. However, application of carbendazim (0.05 %) at first appearance of disease followed by another spray with hexaconazole (0.02 %) ensured significant reduction in pod infection (77 %) and leaf spot intensity (68 %) besides supporting proportionately attractive seed yield (8.62-8.95 q/ha) at an acceptable B:C ratio (6.38:1).

دراسة مرجعية لمرض لفحة الأسكوكيتا على الحمص = A Review of Ascochyta Blight of Chickpea

This article aimed to present detailed literature review on chickpea Ascochyta blight disease. Ascochyta blight caused by Ascochyta rabiei is one of the most biotic stresses reducing chickpea yield. The fungus now exists in the most chickpea growing areas in the world. The most damaging symptoms are stem breakage and pod infection. The life cycle of the fungus consists of a single sexual generation (Didymella rabiei) per season which develops on infected plant debris during winter followed by several asexual generations during the growing season of the crop. The use of resistant cultivars is the most effective, economical and environmentally safe means to manage the disease. Other cultural practices, such as the use of disease free seeds or treated seeds, crop rotation for at least 4 years and deep ploughing of previous infested crop debris accompanied with spraying suitable fungicides in the correct times will minimize the disease severity.

Effect of microwave radiation on dry bean seed infected withColletotrichum lindemuthianumwith and without the use of chemical seed treatment

Friesen, A. P., Conner, R. L., Robinson, D. E., Barton, W. R. and Gillard, C. L. 2014. Effect of microwave radiation on dry bean seed infected with Colletotrichum lindemuthianum with and without the use of chemical seed treatment. Can. J. Plant Sci. 94: 1373–1384. Seed-borne anthracnose, caused by Colletotrichum lindemuthianum, is a serious disease that affects dry bean (Phaseolus vulgaris L.) seed quality and yield. A 2-yr study was conducted to examine the effect of microwave radiation on two bean cultivars, Navigator (navy bean) and AC Ole (pinto bean). In the laboratory, a maximum exposure time between 40–50 s caused <10% decrease in seed germination and 0.14 and 0.10% s−1decrease in pathogen viability for the Navigator and AC Ole cultivars, respectively. Field studies were conducted at Ridgetown and Exeter, ON, to evaluate the effect of microwave radiation and two chemical seed treatments (thiamethoxam+fludioxonil+metalaxyl-M+azoxystrobin and pyraclostrobin+fluxapyroxad+metalaxyl), on emergence, percentage of infection, seed pick, yield and return on investment. Microwave treatment decreased emergence by <10% in both cultivars and decreased disease symptoms by 17–23% for leaf and stem infection in cv. AC Ole when combined with chemical seed treatment. Microwave treatment did not affect pod infection, seed pick, yield, or return on investment, yet chemical treatment increased yield between 9 and 25% in cv. Navigator.

Micronutrient and fungicides management practices to control the Alternaria blight of mustard

Experiments were conducted to evaluate the efficacy of different micronutrients and fungicides against Alternaria brassicae and Alternaria blight on growth and yield contributing attributes of mustard. Among the treatments, T6 showed the highest performance against Alternaria blight in terms of disease incidence. The lowest leaf infection (9.9%), leaf area diseases (2.5%), pod infection (9.3%) and number of spots per pod (0.6) were recorded in T6. Highest leaf infection (56.1%), diseased leaf area (18.31%), pod infection (42.7%) and number of spots per pod (1.9) were recorded in control. The highest yield (1086.0 kg/ha), germination percentage (99.1) and the lowest seed infection (6.5%) of harvested seeds were obtained from the T6, whereas lowest from T1. The performances of micronutrients were better than control but the performances of micronutrients did not differ significantly when it was used in combination with fungicides. DOI: http://dx.doi.org/10.3329/jbas.v38i1.20212 Journal of Bangladesh Academy of Sciences, Vol. 38, No. 1, 61-69, 2014

Field Management of Anthracnose (<i>Colletotrichum lindemuthianum</i>) in Common Bean through Foliar Spray Fungicides and Seed Treatment Bioagents

Common bean anthracnose is a major production constraint in bean growing regions of Ethiopia. This study aimed to determine whether foliar sprays of mancozeb, folpan and mancolaxyl or antagonistic bioagents; Trichoderma harzianum, Trichoderma viride and Pseudomonas fluorescens could reduce anthracnose symptoms and consequently, increase yield and yield components. A total of seven treatments were arranged in a randomized complete block design with three replications. Statistical analysis showed significant differences among treatments. Anthracnose incidence, severity, infected pods per plant and the area under disease progress curve were highest in the control plots compared to the fungicide sprayed and bioagent treated seed plots. The highest percentage of infected pods per plant, 78.9 and 55 were recorded on the control and mancozeb sprayed plots respectively. The highest AUDPC value resulted in the lowest yield of 1.01 t/ha in the control plots compared to a highest yield of 3.33 t/ha from the sprayed plots with folpan and 1.79 t/ha from plots treated with Pseudomonas fluorescens. Relative yield losses of 69.67, 46.25 and 22.82% were recorded from the control, seed treated plots with P. fluorescens and sprayed plots with mancolaxyl respectively. Economic analysis revealed that the highest rate of return of 8,740 was obtained from Pseudomonas fluorescens seed treatment and the highest net benefit; 43,154 on folpan foliar spray treatment. The results of the present study support the novel possibility of using folpan foliar spray and Pseudomonas fluorescens seed treatments to decrease anthracnose symptoms in bean plants and consequently, achieve greater yield.Keywords: Bioagents; Folpan; Pseudomonas fluorescens; Mancolaxyl; seed treatment

English

Black pod is a major hindrance to cocoa production in Nigeria. It is caused by three different Phytophthora species with Phytophthora megakarya as the most important species in Nigeria and West African sub-region. Phytophthora spp. may enhance infections by opportunistic pathogens such as members of the Botryosphaeriacea that cause branch and trunk cankers in many woody plants across the world. Botryosphaeriacea has not been reported in cocoa nor in any woody plants in Nigeria to our knowledge. In the cocoa belt of Nigeria, research and understanding on cocoa black pod and Phytophthora is limited partly because of delayed or no access to some culture media, including required antibiotics. The objectives of this study were to: (1) use locally available materials to develop media for Phytophthora isolation from infected cocoa trees and pods samples and (2) to determine if members of Botryosphaeriaceae are associated with cankers of cocoa trees infected with black pod in Ondo State. The two formulated media, clarified tomato juice agar and cocoa pod agar supported the growth of Phytophthora spp. and were used for isolation from five cocoa producing local government areas, spanning all three senatorial districts of Ondo State. Based on morphological characteristics, four different species of Botryosphaeriaceae were identified from infected cocoa trees/pods but also from citrus and kola trees, which are similar to cocoa and usually planted in the same orchard with cocoa in Nigeria. These findings of new pathogens in cocoa and other hosts in Ondo State indicated the need for new strategies in the management of cocoa diseases in the State and across cocoa producing areas of Nigeria. Key words: Cocoa, Canker, Black pod, pathogens, Botryosphaeriaceae, Phytophthora.

Evaluation the resistance of cocoa clones (Theobroma cacaoL.)

Acceleration on clonal selection of cocoa resistance to pod rot (Phytophthora palmivora)was carried out by early evaluation of the resistance using laboratory test. This research has objective to select the promising clone resistance to P. palmivora for field evaluation. Trials were carried out at the Laboratory of Plant Pathology at the Indonesian Coffee and Cocoa Research Institute using in-vitro inoculation. Isolate of P. palmivorawere collected from the infected pods at Jatirono Estate, Banyuwangi then inoculated to three mature pods of each tested clones. Trials were carried out in two steps to confirm the stability of performance of the resistance. A total of 41 clones were tested in these trials. However due to the availability of pod sample was limited then at 1st trial 31 clones were tested and at 2nd trial 37 clones were tested, both of the test using 27 same clones. The assessed variables were lesion size on pod surface due to Phytophthorainfection at 1st to 7th day after inoculation. The lesion sizes were significantly different among tested clones that performing any variability of the resistance. The variability were grouped into five groups as the resistant classification by which three clones were identified, namely Jano/IV/4/13 (TSH 858 x ICS 13), Jano next to I/7 and Kate/I/10/18 (Sulawesi 01 x TSH 858) consistently performing lowest size of the lesion compared to Sca 6 that could be selected as the resistant clones for field evaluation. Key words: cocoa clones, resistance, pod inoculation, Phytophthora palmivora

Successful pod infections by Moniliophthora roreri result in differential Theobroma cacao gene expression depending on the clone's level of tolerance.

An understanding of the tolerance mechanisms of Theobroma cacao used against Moniliophthora roreri, the causal agent of frosty pod rot, is important for the generation of stable disease-tolerant clones. A comparative view was obtained of transcript populations of infected pods from two susceptible and two tolerant clones using RNA sequence (RNA-Seq) analysis. A total of 3009 transcripts showed differential expression among clones. KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway analysis of differentially expressed genes indicated shifts in 152 different metabolic pathways between the tolerant and susceptible clones. Real-time quantitative reverse transcription polymerase chain reaction (real-time qRT-PCR) analyses of 36 genes verified the differential expression. Regression analysis validated a uniform progression in gene expression in association with infection levels and fungal loads in the susceptible clones. Expression patterns observed in the susceptible clones diverged in tolerant clones, with many genes showing higher expression at a low level of infection and fungal load. Principal coordinate analyses of real-time qRT-PCR data separated the gene expression patterns between susceptible and tolerant clones for pods showing malformation. Although some genes were constitutively differentially expressed between clones, most results suggested that defence responses were induced at low fungal load in the tolerant clones. Several elicitor-responsive genes were highly expressed in tolerant clones, suggesting rapid recognition of the pathogen and induction of defence genes. Expression patterns suggested that the jasmonic acid-ethylene- and/or salicylic acid-mediated defence pathways were activated in the tolerant clones, being enhanced by reduced brassinosteroid (BR) biosynthesis and catabolic inactivation of both BR and abscisic acids. Finally, several genes associated with hypersensitive response-like cell death were also induced in tolerant clones.

Reaction of greengram (Vigna radiata) toCercospora canescens(ell.) and mart

Cercospora canescens was inoculated onto different aged (20–70 days old) plants of greengram (Cv. Shalimar Mung-1). The genotype was found invariably susceptible at all its growth stages with incubation period of 6–7 days and leaf spot diameter of 7.1–7.4mm as recorded after 15 days of inoculation. Total sugar content showed an increasing trend and ranged from 124 to 129 and 133 to 135mg/g dry weight during pre-and post-flowering periods, respectively. The total phenol content also increased with plant age and was maximum (26.5 mg/g dry weigh) in 60 days old plants following which an insignificant decrease (26.5 mg/g dry weight) was recorded. Twenty five genotypes of greengram were screened for resistance against the pathogen under field conditions. The genotypes showed an indifferent response to invasion by C. canescens and none showed absolute resistance. However, five genotypes viz., ML-935, PDM-54, Pusa Vishal, SM-710 and SM-366 were moderately susceptible and manifested lower leaf spot intensity (27.5–30.4%) and pod infection(34–35.4%).

Field Management of Anthracnose (Colletotrichum lindemuthianum) in Common Bean through Fungicides and Bioagents

Common bean anthracnose is a major production constraint in bean growing regions of Ethiopia. This study aimed to determine whether foliar sprays of mancozeb, folpan and mancolaxyl or antagonistic bioagents; Trichoderma harzianum, Trichoderma viride and Pseudomonas fluorescens could reduce anthracnose symptoms and consequently, increase yield and yield components. A total of seven treatments were arranged in a randomized complete block design with three replications. Statistical analysis showed significant differences among treatments. Anthracnose incidence, severity, infected pods per plant and the area under disease progress curve were highest in the control plots compared to the fungicide sprayed and bioagent treated seed plots. The highest percentage of infected pods per plant of 78.9 and 55.0 recorded on the control and mancozeb sprayed plots, respectively. The highest AUDPC value resulted in the lowest yield of 1.01 t/ha in the control plots compared to a highest yield of 3.3 t/ha from the sprayed plots with folpan and 1.8 t/ha from plots treated with Pseudomonas fluorescens. Relative yield losses of 69.7, 46.3 and 22.8% were recorded from the control, seed treated plots with P. fluorescens and sprayed plots with mancolaxyl, respectively. Economic analysis revealed that the highest rate of return of 8,740 was obtained from Pseudomonas fluorescens seed treatment and the highest net benefit value of 43,154 calculated on folpan foliar spray treatment. The results of the present study support the novel possibility of using folpan foliar spray and Pseudomonas fluorescens seed treatments to decrease anthracnose symptoms in common bean and consequently, achieve greater yield.

Genome and secretome analysis of the hemibiotrophic fungal pathogen, Moniliophthora roreri, which causes frosty pod rot disease of cacao: mechanisms of the biotrophic and necrotrophic phases.

BackgroundThe basidiomycete Moniliophthora roreri is the causal agent of Frosty pod rot (FPR) disease of cacao (Theobroma cacao), the source of chocolate, and FPR is one of the most destructive diseases of this important perennial crop in the Americas. This hemibiotroph infects only cacao pods and has an extended biotrophic phase lasting up to sixty days, culminating in plant necrosis and sporulation of the fungus without the formation of a basidiocarp.ResultsWe sequenced and assembled 52.3 Mb into 3,298 contigs that represent the M. roreri genome. Of the 17,920 predicted open reading frames (OFRs), 13,760 were validated by RNA-Seq. Using read count data from RNA sequencing of cacao pods at 30 and 60 days post infection, differential gene expression was estimated for the biotrophic and necrotrophic phases of this plant-pathogen interaction. The sequencing data were used to develop a genome based secretome for the infected pods. Of the 1,535 genes encoding putative secreted proteins, 1,355 were expressed in the biotrophic and necrotrophic phases. Analysis of the data revealed secretome gene expression that correlated with infection and intercellular growth in the biotrophic phase and invasive growth and plant cellular death in the necrotrophic phase.ConclusionsGenome sequencing and RNA-Seq was used to determine and validate the Moniliophthora roreri genome and secretome. High sequence identity between Moniliophthora roreri genes and Moniliophthora perniciosa genes supports the taxonomic relationship with Moniliophthora perniciosa and the relatedness of this fungus to other basidiomycetes. Analysis of RNA-Seq data from infected plant tissues revealed differentially expressed genes in the biotrophic and necrotrophic phases. The secreted protein genes that were upregulated in the biotrophic phase are primarily associated with breakdown of the intercellular matrix and modification of the fungal mycelia, possibly to mask the fungus from plant defenses. Based on the transcriptome data, the upregulated secreted proteins in the necrotrophic phase are hypothesized to be actively attacking the plant cell walls and plant cellular components resulting in necrosis. These genes are being used to develop a new understanding of how this disease interaction progresses and to identify potential targets to reduce the impact of this devastating disease.