scholarly journals Crown Rot of Strawberry Caused by Macrophomina phaseolina in California

Plant Disease ◽  
2008 ◽  
Vol 92 (8) ◽  
pp. 1253-1253 ◽  
Author(s):  
S. T. Koike
Keyword(s):  
Disease Incidence ◽  
Pathogenic Fungi ◽  
Macrophomina Phaseolina ◽  
The United States ◽  
Crown Rot ◽  
Charcoal Rot ◽  
Crown Tissue ◽  
Original Field ◽  
Rot Disease ◽  
Eventual Collapse

In 2006 and 2007, severely diseased strawberry (Fragaria × ananassa) plants were observed in five commercial fields in southern California (Orange County). Disease generally occurred in discrete patches. Within such patches, disease incidence ranged from 10 to 75%. Symptoms consisted of wilting of foliage, drying and death of older leaves, plant stunting, and eventual collapse and death of plants. When plant crowns were dissected, internal vascular and cortex tissues were dark brown to orange brown. Fruiting bodies or other fungal structures were not observed. A fungus was consistently isolated from symptomatic crown tissue that had been surface sterilized and placed on acidified corn meal agar (LA-CMA). All isolates produced numerous, dark, irregularly shaped sclerotia that were 67 to 170 μm long and 44 to 133 μm wide. When isolates were grown on 1.5% water agar with dried and sterilized wheat straw, dark, ostiolate pycnidia and hyaline, single-celled, cylindrical conidia were produced. On the basis of these characters, all isolates were identified as Macrophomina phaseolina (1). The symptomatic plants tested negative for Colletotrichum spp., Phytophthora spp., Verticillium dahliae, and other pathogens. Inoculum for pathogenicity tests was produced by growing six isolates on CMA on which sterilized wood toothpicks were placed on the agar surface. After 1 week, toothpicks were removed and inserted 4 to 5 mm deep into the basal crown tissue of potted strawberry plants (cv. Camarosa) grown in soilless, peatmoss-based rooting medium. Ten plants were inoculated per isolate and one toothpick was inserted per plant. Ten control strawberry plants were treated by inserting one sterile toothpick into each crown. All plants were then grown in a shadehouse. After 2 weeks, all inoculated plants began to show wilting and decline of foliage. By 4 weeks, all inoculated plants had collapsed. Internal crown tissue was discolored and similar in appearance to the original field plants. M. phaseolina was isolated from all inoculated plants. Control plants did not exhibit any disease symptoms, and crown tissue was symptomless. The test was repeated and the results were similar. While M. phaseolina has been periodically associated with strawberry in California (3), to my knowledge, this is the first report of charcoal rot disease on commercial strawberry in California. Charcoal rot of strawberry has been reported in Egypt, France, India, Israel, and the United States (Florida and Illinois) (2,4). Similar to previous reports (2,4), many of the affected California fields were not preplant fumigated with methyl bromide + chloropicrin fumigants, and it is possible that under these changing production practices this pathogen may increase in importance in California. References: (1) P. Holliday and E. Punithalingam. No. 275 in: Descriptions of Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, UK, 1970. (2) J. Mertely et al. Plant Dis.89:434, 2005. (3) S. Wilhelm. Plant Dis. Rep. 41:941, 1957. (4) A. Zveibil and S. Freeman. Plant Dis. 89:1014, 2005.

scholarly journals Occurrence of Charcoal Rot Caused by Macrophomina phaseolina on Canola in Argentina

Plant Disease ◽  
2006 ◽  
Vol 90 (4) ◽  
pp. 524-524 ◽  
Author(s):  
S. A. Gaetán ◽  
L. Fernandez ◽  
M. Madia
Keyword(s):  
United States ◽  
Buenos Aires ◽  
Vascular Tissue ◽  
Disease Incidence ◽  
Pathogenic Fungi ◽  
Macrophomina Phaseolina ◽  
The United States ◽  
Buenos Aires Province ◽  
Charcoal Rot ◽  
Experimental Plots

Canola (Brassica napus) is an important oleaginous crop in Argentina. Approximately 16,000 ha are grown commercially in the southern region of Buenos Aires Province. In 2003, typical symptoms and signs of charcoal rot were observed on canola plants in experimental plots located at the School of Agricultural Sciences, University of Buenos Aires in Buenos Aires. Average disease incidence across three 5- to 6-month-old plants (cvs. Monty, Rivette, and Trooper) was 12% (range = 7 to 17%). Affected plants appeared in patches following the rows at pod-filling stage. Symptoms included wilted foliage, premature senescence, and death of plants. Black, spherical microsclerotia 78 to 95 μm in diameter were present in vascular tissue of basal stems and taproots. The affected plants were stunted and had unfilled pods. In advanced phases of the disease, areas of silver gray-to-black discoloration were observed in the stem cortex; many plants were killed during late-grain fill, and plants could be pulled easily from the ground because basal stems were shredded. Four samples consisting of five symptomatic plants per sample were randomly collected from experimental plots. Pieces (1-cm long) taken from taproots and basal stems of diseased plants were surface sterilized with 1% NaOCl for 2 min and then placed on potato dextrose agar (PDA). Plates were incubated in the dark at 26°C for 4 days and then exposed to 12-h NUV light/12-h dark for 6 days. Five resulting isolates were identified as Macrophomina phaseolina (Tassi) Goidanich (1) based on the gray color of the colony and the presence of microsclerotia 71 to 94 μm in diameter. Two colonies developed globose pycnidia with one-celled, hyaline, and elliptic conidia. Pathogenicity tests were conducted using four inoculated and three non-inoculated control plants potted in a sterilized soil mix (soil/sand, 3:1) in a greenhouse at 25°C and 75% relative humidity with no supplemental light. Crown inoculations were carried out by placing a disk taken from an actively growing culture of M. phaseolina into wounds made with a sterile scalpel. Control plants received disks of sterile PDA. Inoculated and control plants were covered with polyethylene bags for 48 h after inoculation. Three isolates caused disease on 7-week-old canola plants (cvs. Master, Mistral, Rivette, and Trooper). Characteristic symptoms similar to the original observations developed for all three isolates within 21 days after inoculation on 80% of inoculated plants. The pathogen was successfully reisolated from diseased stem tissue in all instances. Symptoms included leaf necrosis, stunting, decay and collapse of seedlings, and plant death. Control plants remained asymptomatic. The experiment was repeated once with similar results. To our knowledge, this is the first report of the occurrence of M. phaseolina causing charcoal rot on canola in Argentina. This pathogen has been previously reported in the United States (2,3). The results demonstrate the potential importance of this pathogen in Argentina, since two commercial cultivars (Master and Mistral) were apparently susceptible to M. phaseolina. More studies are needed to determine the presence of charcoal rot in canola-growing areas of Argentina. References: (1) Anonymous. Macrophomina phaseolina. No. 275 in: Descriptions of Plant Pathogenic Fungi and Bacteria. CMI, Kew, Surrey, UK, 1970. (2) R. E. Baird et al. Plant Dis. 78:316, 1994. (3) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St. Paul, MN, 1989.

scholarly journals First Report of a Root and Crown Rot Disease of Myrtle in California Caused by Cylindrocladium pauciramosum

Plant Disease ◽  
2001 ◽  
Vol 85 (4) ◽  
pp. 448-448 ◽  
Author(s):  
S. T. Koike ◽  
P. W. Crous
Keyword(s):  
Species Complex ◽  
The United States ◽  
Crown Rot ◽  
Conidial Suspension ◽  
First Report ◽  
Potted Plants ◽  
Crown Tissue ◽  
Root And Crown Rot ◽  
Plant Pathol ◽  
Rot Disease

Myrtle (Myrtus communis) is a woody, evergreen plant used in California as a landscape shrub or potted plant. In 2000, a new root and crown disease was found in commercial nursery myrtle being grown as potted plants. Roots were necrotic and crown tissue was brown. Affected plants became gray-green in color, withered, and died. A Cylindrocladium sp. was consistently isolated from roots, crowns, and lower stems of symptomatic plants. Isolates were characterized by having penicillate conidiophores terminating in obpyriform to broadly ellipsoidal vesicles. Conidia were hyaline, 1-septate, straight with rounded ends, (50-) 53 to 56 (-58) × (3.5-) 4 to 6 μm, placing it in the Cylindrocladium candelabrum Viégas species complex. Single-conidial isolates (STE-U 4012 to 4018) produced perithecia with viable progeny of Calonectria pauciramosa C.L. Schoch & Crous when mated on carnation leaf agar with tester strains of Cylindrocladium pauciramosum C.L. Schoch & Crous (2). Matings with tester strains of all other species in this complex proved unsuccessful. Only one mating type of C. pauciramosum has thus far been found in the United States. Pathogenicity of representative isolates was confirmed by applying 5 ml of a conidial suspension (1.0 × 106 conidia/ml) to the crowns of potted, 5-month-old, rooted mytle cuttings that were subsequently maintained in a greenhouse (23 to 25°C). After 4 weeks, plant crowns and roots developed symptoms similar to those observed in the nursery, and plants later wilted and died. C. pauciramosum was re-isolated from all plants. Control plants, which were treated with water, did not develop any symptoms. The tests were repeated and the results were similar. This is the first report of C. pauciramosum as a pathogen of myrtle in California. The disease has been reported on myrtle in Europe (1). References: (1) G. Polizzi and P. W. Crous. Eur. J. Plant Pathol. 105:407, 1999. (2) C. L. Schoch et al. Mycologia 91:286, 1999.

scholarly journals SURVEY, VARIETAL REACTION AND CHEMICAL CONTROL OF STRAWBERRY CHARCOAL ROT IN EGYPT

2019 ◽  
Vol 31 (1) ◽  
pp. 55-66
Author(s):  
Ramadan A. Bakr ◽  
Abdullah S. Hamad
Keyword(s):  
Disease Incidence ◽  
Macrophomina Phaseolina ◽  
Mycelium Growth ◽  
Charcoal Rot ◽  
In Vivo Experiments ◽  
Survival Percentage ◽  
Rot Disease ◽  
Chemical Fungicides

A survey was carried out to know the occurrence of charcoal rot disease of strawberry caused by Macrophomina phaseolina in different selected locations representing different soil types during the growing season of strawberry in Badr and Kom Hamada Districts in El-Behira governorate, Egypt. Also, the effect of five chemical fungicides at five concentrations was determined in vitro and in vivo experiments against M. phaseolina compared to the control. A total of 69 strawberry samples collected from farmer’s fields. Disease incidence (DI) and percentage of disease incidence (PDI) and disease index were recorded. Results revealed that percentage of disease incidence varies among the surveyed locations. Macrophomina phaseolina isolates M3 and M4 were the most destructive isolates. Results indicate that the selected Four strawberry cultivars showed different susceptibility to charcoal rot and Festival was the high susceptible cultivar. Our findings revealed that at 100 ppm concentration the most of the fungicides used inhibited the M. phaseolina mycelium growth, however the higher rate was recorded with Sendo by 91.95 % followed by 91.12% in Rhizolex-T and the least rate was recorded with Ridomil gold plus by 31.67%. At 200 ppm Rhizolex-T gave the highest inhibition by 96.67%, followed by Sendo and Sandcur by 95.96 and 95.00 % respectively while Ridomil gold plus gave the least inhibition rate by 43.06%.Results illustrated that use of fungicides markedly increased the survival of strawberry plants. The highest plant survival percentage was recorded with Rhizolex-T by 80% followed Sendo by 60%, while least plants survival percentage was recorded with Ridomil gold plus by10% compared with infected untreated control.

scholarly journals First Report of Charcoal Rot Epidemics Caused by Macrophomina phaseolina in Soybean in Iowa

Plant Disease ◽  
2005 ◽  
Vol 89 (5) ◽  
pp. 526-526 ◽  
Author(s):  
X. B. Yang ◽  
S. S. Navi
Keyword(s):  
Disease Incidence ◽  
Cropping System ◽  
Premature Death ◽  
Macrophomina Phaseolina ◽  
The United States ◽  
Reference Source ◽  
American Phytopathological Society ◽  
Charcoal Rot ◽  
Integrated Crop Management ◽  
Soybean Diseases

Macrophomina phaseolina, the causal agent of soybean charcoal rot, is widely present in soil and has been reported to cause yield losses of 30 to 50%, mainly in southern soybean production regions of the United States. (2). Charcoal rot was first reported in North Dakota during 2002, suggesting a range expansion for M. phaseolina (1). Charcoal rot has been occasionally observed in Iowa in individual soybean plants, but epidemics of the disease have not been recorded. During the 2003 growing season, a severe epidemic of charcoal rot was observed throughout the state. Diseased plants were first noticed in late July and by late August, patches of diseased plants wilted and died prematurely in many fields. The pith of diseased plants had a brown discoloration in taproots and lower stems. Symptoms were observed up to the 4th or 5th nodes, typical of charcoal rot. In some plants, no discoloration was evident. In discolored plants, microsclerotia of M. phaseolina were commonly observed in the epidermis, just beneath the epidermis, and inside taproots and lower stems of wilted plants. A systematic survey was conducted between late August and early September, 2003 to determine the prevalence and severity of charcoal rot in Iowa. The disease was observed in 60% of fields surveyed in northern Iowa (north of latitude 42.5°N), 90% in central Iowa (latitude 41.6 to 42.5°N), and 20% in southern Iowa (south of latitude 41.6°N). Incidence in surveyed fields ranged from 10 to 80%. One 80-ha field in Hampton (northern Iowa) had 50% disease incidence. An incidence of 80%, with extensive premature death prior to growth stage R6 (full seed), was observed in a 16-ha field east of Huxley (central Iowa). The fungus was isolated by splitting open the tap roots of a few representative symptomatic plants from 18 fields. Tissue colonized with microsclerotia of M. phaseolina was scraped, collected in sterile petri dishes, surface sterilized in 1% sodium hypochlorite, washed in distilled sterile water, and transferred to potato dextrose agar. The plates were incubated for 2 weeks at 22 ± 1°C on laboratory benches with a 12-h photoperiod. All resulting cultures produced abundant microscleorotia of M. phaseolina similar to those described by Smith and Wyllie (3). Pycnidia were observed in two cultures. August 2003 was the driest month on record in Iowa, which may have contributed to the outbreaks of this disease. Statewide, yield in Iowa soybean during 2003 was 1,976.1 kg/ha (2,798 kg/ha in 2002). The largescale epidemic of charcoal rot may have contributed to the overall reduction in soybean productivity in Iowa in 2003 (4). Since M. phaseolina also infects corn (2), and corn/soybean rotation is the most common cropping system in Iowa, efforts are needed to address the future risk of M. phaseolina to corn and soybean. References: (1) C. A. Bradley and L. E. del Rio. Plant Dis. 87:601, 2003. (2) D. C. McGee. Soybean Diseases: A Reference Source for Seed Technologists. The American Phytopathological Society, St. Paul, MN, 1992; (3) G. S. Smith and T. D. Wyllie. Charcoal rot. Pages 29–31 in: Compendium of Soybean Diseases. 4th ed. G. L. Hartman et al., eds. The American Phytopathological Society, St. Paul, MN, 1999. (4). X. B. Yang et al. Biology and management of soybean charcoal rot. Pages 55–60. in: Proc. 15th Integrated Crop Management Conf. Iowa State University, Ames. 2003.

scholarly journals Biocontrol of Soybean Charcoal Root Rot Disease by Using Trichoderma spp.

2016 ◽  
Vol 49 (2) ◽  
pp. 41-51 ◽  
Author(s):  
H. Barari ◽  
A. Foroutan
Keyword(s):  
Disease Incidence ◽  
Macrophomina Phaseolina ◽  
Field Trials ◽  
Trichoderma Spp ◽  
Charcoal Rot ◽  
Oilseed Crops ◽  
Glycine Max L ◽  
Rot Disease ◽  
Major Factors ◽  
1000 Grain Weight

AbstractMacrophomina phaseolina (Tassi) Goid, causing charcoal rot disease of soybean, is one of the major factors threatening soybean production, especially in dry years. This pathogen remains the prevailing causal agent of charcoal rot disease that significantly suppresses the yield of a variety of oilseed crops. Its wide host range and ability to survive under arid conditions, coupled with the ineffective use of fungicides against it, have spurred scientific endeavours for alternative avenues to control this phytopathogen. Hence, the present study aimed to provide empirical evidence of the efficacy of fungal isolates of Trichoderma spp. as biological control agents against charcoal rot in soybean (Glycine max L.). In this study Trichoderma harzianum strains 6, 14, 17, 21, 44, T. asperellum 26 and T. virens 32 were evaluated as potential biological agents for control of this disease. Mycelial growth of M. phaseolina strain h-7 was reduced by cell-free and volatile metabolites of Trichoderma strains by 16.4 to 64.8%. T. harzianum strain Tj17 significantly (p≤0.05) reduced the incidence (to 7.3%) and severity (to 3%) of disease 42 days after inoculation and increased the 1000 grain weight (to 178 g) in greenhouse conditions. For confirmation of the greenhouse tests, the selected antagonists were re-examined in field trials, where this isolate reduced the disease incidence (to 10%) and severity (to 3%). The overall results of this study show high capability of used antagonists in reduction of disease severity and incidence, and resulting in increased weight of the product. Hence, the findings reported in the present study supported the applicability of Tj17 isolate as possible alternative to fungicides for the control of charcoal rot in soybean.

scholarly journals Charcoal Rot of Strawberries Caused by Macrophomina phaseolina

EDIS ◽  
2007 ◽  
Vol 2007 (20) ◽  
Author(s):  
Natalia A. Peres ◽  
James C. Mertely
Keyword(s):  
Plant Pathology ◽  
Macrophomina Phaseolina ◽  
Causal Agent ◽  
Crown Rot ◽  
Disease Development ◽  
Charcoal Rot ◽  
Fact Sheet ◽  
Rot Disease ◽  
And Control

PP 242, a 2-page illustrated fact sheet by N.A. Peres and James C. Mertely, describes this new crown-rot disease in Florida -- causal agent and symptoms, disease development and spread, and control. Published by the UF Department of Plant Pathology, November 2007. PP242/PP161: Charcoal Rot of Strawberries Caused by Macrophomina phaseolina (ufl.edu)

scholarly journals Occurrence of Macrophomina phaseolina in Israel: Challenges for Disease Management and Crop Germplasm Enhancement

Plant Disease ◽  
2021 ◽  
Author(s):  
Roni Cohen ◽  
Meital Elkabez ◽  
Harry Paris ◽  
Amit Gur ◽  
Nir Dai ◽  
...  
Keyword(s):  
Global Climate ◽  
Disease Incidence ◽  
Macrophomina Phaseolina ◽  
Great Promise ◽  
Cell Wall Degrading Enzymes ◽  
Charcoal Rot ◽  
Rot Disease ◽  
Crop Germplasm ◽  
Reliable Methods ◽  
Elite Germplasm

Macrophomina phaseolina is a soil-borne fungal pathogen infecting many important crop plants. The fungus, which can survive on crop debris for a long period of time, causes charcoal rot disease by secreting a diverse array of cell-wall degrading enzymes and toxins. M. phaseolina thrives during periods of high temperatures and arid conditions, as typically occuring in Israel and other countries with a Mediterranean climate. Crop losses due to charcoal rot can be expected to increase and spread to other countries in a warming global climate. Management of this pathogen is challenging, requiring an array of approaches for the various crop hosts. Approaches that have had some success in Israel include grafting of melons and watermelons on resistant squash rootstocks and soil application of fungicide to reduce disease incidence in melons, fumigation and alterations in planting date and mulching of strawberries, and alteration in irrigation regime of cotton. Elsewhere, these approaches as well as soil amendments, and addition of organisms that are antagonistic to M. phaseolina have had success in some crop situations. Management through host resistance would be the most sustainable approach, but requires identifying resistant germplasm for each crop and introgressing the resistance into the leading cultivars. Resistance to charcoal rot is under complex genetic control in most crops, posing a great challenge for its introgression into elite germplasm. Moreover, fast, reliable methods of screening for resistance would have to be developed for each crop. The toothpick-inoculation method used by us holds great promise for selecting resistant germplasm for melons and possibly for sesame, but other methodologies have to be devised for each individual crop.

scholarly journals Potential of few fungicides and plant extracts for managing charcoal rot of soybean caused by Macrophomina phaseolina (Tassi) Gold. in Madhya Pradesh, India

2020 ◽  
Vol 12 (3) ◽  
pp. 388-393
Author(s):  
Sanjay ◽  
Sanjeev Kumar ◽  
Bal Kishan Chaudhary
Keyword(s):  
Plant Extracts ◽  
Field Condition ◽  
Disease Incidence ◽  
Macrophomina Phaseolina ◽  
Madhya Pradesh ◽  
Citrus Limon ◽  
Charcoal Rot ◽  
Thiophanate Methyl ◽  
Rot Disease

Charcoal rot disease of soybean caused by Macrophomina phaseolina is a serious problem in most of the soybean growing area of Madhya Pradesh. In this study, seven plant extracts viz., leaves of Azadirachta indica, Citrus limon, Polyalthia longifolia, Parthenium hysterophorus and Ricinus communis, bulb of Allium sativum and Allium cepa and eight fungicides  viz., Captan (0.25%), Mancozeb (0.25%), Carbendazim + Mancozeb (25%), Thiophanate Methyl (0.1%), Pyraclostrobin (0.2%), Carbendazim (0.1%) and Blue copper (0.3% )  were evaluated for an effective management of charcoal rot of soybean caused by M. phaseolina (Tassi) Goid under in vitro and in vivo condition. Among plant extracts, garlic clove extract was found most effective showing 77.3 %  growth inhibition and poor microslerotia formation of M. phaseolina by 77.3 % followed by parthenium leaf extract (75.2% inhibition) at 15 % concentration. Two soil drenching of garlic clove extracts @ 15.0 % concentration also found most effective for the management of disease under field condition recorded minimum disease incidence (13.5%) and highest yield (14.6q/ha). Among fungicides, Carbendazim (0.1%) and Thiophanate Methyl (0.1%) showed 100 % inhibition of radial growth and microsclerotia production of M phaseolina under in vitro condition. Two soil drenching of Carbendazim @ 0.1%  found to be most effective for the management of charcoal rot of soybean under field condition showing minimum disease incidence (5.36%) and producing highest yield (16.0 q/ha) followed by Thiophanate Methyl. These results suggested that the toxic effect of Carbendazim  and Thiophanate Methyl  and  A. sativum inhibited maximum mycelium growth in vitro and provide management of charcoal rot disease under field conditions.

scholarly journals Toxin Production in Soybean (Glycine max L.) Plants with Charcoal Rot Disease and by Macrophomina phaseolina, the Fungus that Causes the Disease

Toxins ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 645 ◽  
Author(s):  
Hamed K. Abbas ◽  
Nacer Bellaloui ◽  
Cesare Accinelli ◽  
James R. Smith ◽  
W. Thomas Shier
Keyword(s):  
Culture Media ◽  
Leaf Disc ◽  
Toxin Production ◽  
Macrophomina Phaseolina ◽  
Economic Losses ◽  
Limit Of Quantification ◽  
Charcoal Rot ◽  
Wide Range ◽  
Soybean Plants ◽  
Rot Disease

Charcoal rot disease, caused by the fungus Macrophomina phaseolina, results in major economic losses in soybean production in southern USA. M. phaseolina has been proposed to use the toxin (-)-botryodiplodin in its root infection mechanism to create a necrotic zone in root tissue through which fungal hyphae can readily enter the plant. The majority (51.4%) of M. phaseolina isolates from plants with charcoal rot disease produced a wide range of (-)-botryodiplodin concentrations in a culture medium (0.14–6.11 µg/mL), 37.8% produced traces below the limit of quantification (0.01 µg/mL), and 10.8% produced no detectable (-)-botryodiplodin. Some culture media with traces or no (-)-botryodiplodin were nevertheless strongly phytotoxic in soybean leaf disc cultures, consistent with the production of another unidentified toxin(s). Widely ranging (-)-botryodiplodin levels (traces to 3.14 µg/g) were also observed in the roots, but not in the aerial parts, of soybean plants naturally infected with charcoal rot disease. This is the first report of (-)-botryodiplodin in plant tissues naturally infected with charcoal rot disease. No phaseolinone was detected in M. phaseolina culture media or naturally infected soybean tissues. These results are consistent with (-)-botryodiplodin playing a role in the pathology of some, but not all, M. phaseolina isolates from soybeans with charcoal rot disease in southern USA.

scholarly journals Progress of soybean charcoal rot under tillage and no-tillage systems in Brazil

2003 ◽  
Vol 28 (2) ◽  
pp. 131-135 ◽  
Author(s):  
Álvaro M. R. Almeida ◽  
Lilian Amorim ◽  
Armando Bergamin Filho ◽  
Eleno Torres ◽  
José R. B. Farias ◽  
...  
Keyword(s):  
Cropping Systems ◽  
Disease Incidence ◽  
Cropping System ◽  
Macrophomina Phaseolina ◽  
Conventional System ◽  
Survival Times ◽  
Charcoal Rot ◽  
No Till ◽  
Four Seasons ◽  
Conventional Systems

The increase in incidence of charcoal rot caused by Macrophomina phaseolina on soybeans (Glycine max) was followed four seasons in conventional and no-till cropping systems. In the 1997/98 and 2000/01 seasons, total precipitation between sowing and harvest reached 876.3 and 846.9 mm, respectively. For these seasons, disease incidence did not differ significantly between the no-till and conventional systems. In 1998/99 and 1999/00 precipitation totaled 689.9 and 478.3 mm, respectively. In 1998/99, in the no-till system, the disease incidence was 43.7% and 53.1% in the conventional system. In 1999/00 the final incidence was 68.7% and 81.2% for the no-till and conventional systems, respectively. For these two seasons, precipitation was lower than that required for soybean crops (840 mm), and the averages of disease incidence were significantly higher in the conventional system. The concentration of microsclerotia in soil samples was higher in samples collected in conventional system at 0 - 10 cm depth. However, analysis of microsclerotia in roots showed that in years with adequate rain no difference was detected. In dry years, however, roots from plants developed under the conventional system had significantly more microsclerotia. Because of the wide host range of M. phaseolina and the long survival times of the microsclerotia, crop rotation would probably have little benefit in reducing charcoal rot. Under these study conditions it may be a better alternative to suppress charcoal rot by using the no-till cropping system to conserve soil moisture and reduce disease progress.

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