scholarly journals Diversity and Virulence of Alternaria spp. Causing Potato Early Blight and Brown Spot in Wisconsin

2019 ◽  
Vol 109 (3) ◽  
pp. 436-445 ◽  
Author(s):  
Shunping Ding ◽  
Kiana Meinholz ◽  
Kenneth Cleveland ◽  
Stephen A. Jordan ◽  
Amanda J. Gevens
Keyword(s):  
Early Blight ◽  
Elongation Factor ◽  
Alternaria Solani ◽  
Potato Production ◽  
Russet Burbank ◽  
Brown Spot ◽  
Breeding Line ◽  
Quinone Outside Inhibitor ◽  
Significant Difference ◽  
Promising Source

Early blight, caused by Alternaria solani, along with brown spot, caused by A. alternata, have the potential to reduce quality and yield in potato production globally. Prior to this study, the incidence, disease impact, and fungicide resistance attributes of A. alternata in Wisconsin were poorly understood. Potato pathogens were isolated from foliar lesions at three commercial locations in Wisconsin in 2012 and 2017 and were initially morphologically identified as A. solani (n = 33) and A. alternata (n = 40). Identifications were further corroborated with the phylogenetic analysis of the internal transcribed spacer (ITS), translation elongation factor 1 (TEF1), gapdh, Alt a 1, and OPA10-2. A multigene phylogeny of ITS, TEF1, gapdh, and Alt a 1 showed five genotypes of A. alternata and one single genotype of A. solani. We demonstrated that the A. alternata isolates were virulent on potato cultivars Russet Burbank (P < 0.013) and Atlantic (P < 0.0073), though they caused less disease than A. solani (P < 0.0001 and P < 0.0001, respectively). A. alternata caused little disease on the breeding line 24-24-12 (P = 0.9929), and A. solani caused fewer disease symptoms on 24-24-12 than on Russet Burbank (P < 0.0001) or Atlantic (P < 0.0001). Breeding line 24-24-12 may be a promising source of potential resistance for the two diseases. There was no significant difference in virulence of different A. alternata genotypes, and no significant difference in virulence or genotype clustering among isolates from the three locations. Isolates of A. alternata that induced chlorosis caused larger lesion areas than isolates that did not in Russet Burbank (P < 0.0001), Atlantic (P < 0.0001), and 24-24-12 (P = 0.0365). There was no significant difference in virulence between quinone outside inhibitor (QoI)-sensitive and QoI-resistant isolates of A. alternata. This study enhanced our understanding of potato early blight and brown spot in Wisconsin, and suggested that A. alternata in addition to A. solani should be carefully monitored and possibly uniquely managed in order to achieve overall disease control.

scholarly journals Spatiotemporal Distribution of Potato-Associated Alternaria Species in Wisconsin

Plant Disease ◽  
2021 ◽  
Vol 105 (1) ◽  
pp. 149-155
Author(s):  
Shunping Ding ◽  
Kiana Meinholz ◽  
Amanda J. Gevens
Keyword(s):  
Disease Severity ◽  
Early Blight ◽  
Management Strategies ◽  
Alternaria Solani ◽  
Distribution Patterns ◽  
Potato Production ◽  
Brown Spot ◽  
Alternaria Species ◽  
Production Area ◽  
Common Potato

Potato early blight caused by Alternaria solani and potato brown spot caused by Alternaria alternata are two common potato foliar diseases. Fungicide applications in Wisconsin target early blight with the expectation of managing brown spot simultaneously. However, distributions of the two pathogens over time and space have not been previously reported in Wisconsin. In this study, six potato fields in Wisconsin were systematically sampled during 2014 to 2017 to investigate the incidences of both pathogens; incidences of the pathogens were compared by location, timing, and year. Incidence of A. alternata had been recorded starting in late June in every field every year, whereas incidence of A. solani started later in some of the fields. At the end of each growing season throughout the four years, the highest incidence (100% most of the years) of A. solani was observed in a field in Plover, located in a concentrated potato production area of central Wisconsin, and a field in Arena, located in an isolated potato production area in southern Wisconsin. The highest incidence (100% every year) of A. alternata was observed in a field in Madison, an isolated potato field that was managed organically. Such distribution patterns could be a result of the different host ranges of the pathogens and abundance of inoculum in different geographic locations. In 2016, disease severity was correlated with the incidence of both pathogens (P < 0.0001 to P = 0.0299), but in 2017, disease severity was correlated with the incidence of A. solani in most of the fields (P < 0.0001 to P = 0.0799). These findings suggest that both Alternaria spp. are important for considering disease management strategies in central and southern Wisconsin.

Impact of SDH Mutations in Alternaria solani on Recently Developed SDHI Fungicides Adepidyn and Solatenol

Plant Disease ◽  
2021 ◽  
Author(s):  
Sarah Rodriguez ◽  
Rhodesia Celoy ◽  
Ipsita Mallik ◽  
Julie Sherman Pasche ◽  
Neil C Gudmestad
Keyword(s):  
Early Blight ◽  
Field Experiments ◽  
Alternaria Solani ◽  
Potato Production ◽  
Field Trials ◽  
Intrinsic Activity ◽  
In Vitro Assays ◽  
Commercial Application ◽  
Quinone Outside Inhibitor

Early blight, caused by Alternaria solani, is observed annually in all midwestern potato production areas. The use of foliar fungicides remains a primary management strategy. However, A. solani has developed reduced-sensitivity or resistance to many single-site fungicides such as quinone outside inhibitor (QoI, FRAC group 11), succinate dehydrogenase inhibitor (SDHI, FRAC group 7), demethylation inhibitors (DMI, FRAC group 3), and anilinopyrimidine (AP, FRAC group 9) fungicides. Boscalid, fluopyram, solatenol, and adepidyn are EPA-registered SDHI fungicides used commercially on a variety of crops, including potato. Five SDH mutations have been characterized previously in A. solani that affect the efficacy of boscalid while only one of these mutations has been demonstrated to negatively affect fluopyram efficacy. Conidial germination assays were used to determine if a shift in sensitivity has occurred in these SDHI fungicides. Alternaria solani isolates collected prior to the commercial application of SDHI fungicides (baseline) and were compared to recently collected isolates (non-baseline). Greenhouse evaluations were conducted also to evaluate the efficacy of boscalid, fluopyram, solatenol, and adepidyn on A. solani isolates possessing individual SDH mutations. Additionally, field trials were conducted to determine the effects application of these SDHI fungicides on the frequency of SDH mutations. Fluopyram, solatenol, and adepidyn had high intrinsic activity against A. solani when compared to boscalid, based on in vitro assays. The application of adepidyn and solatenol resulted in greater early blight control than the application of boscalid and fluopyram in greenhouse experiments. Molecular characterization of A. solani isolates collected from the field trials determined that the frequency of the H134R-mutation can increase in response to more recently developed SDHI fungicides. In contrast, the H278R/Y- and H133R-mutations decreased to the point of being nearly absent in these field experiments.

scholarly journals Effect of strobilurin fungicides on control of early blight (Alternaria solani) and yield of potatoes grown under two N fertility regimes

2007 ◽  
Vol 88 (1) ◽  
pp. 9-15 ◽  
Author(s):  
William MacDonald ◽  
Rick D. Peters ◽  
Robert H. Coffin ◽  
Christian Lacroix
Keyword(s):  
Prince Edward Island ◽  
Early Blight ◽  
Tuber Yield ◽  
Alternaria Solani ◽  
Field Trials ◽  
Potato Yield ◽  
Russet Burbank ◽  
Strobilurin Fungicides ◽  
N Fertility

Early blight, caused by Alternaria solani, is a ubiquitous disease that can reduce potato yield. Adequate crop fertility and appropriate fungicide applications usually suppress the development of this disease. Field trials were established in Prince Edward Island to determine whether strobilurin analogs, namely azoxystrobin and pyraclostrobin, could suppress early blight of potatoes (cvs. Shepody and Russet Burbank) grown under two nitrogen (N) fertility regimes (high or low N). Azoxystrobin and pyraclostrobin were linked to significantly higher total tuber yield for Russet Burbank in 2003 and Shepody in 2004 when compared to plots receiving no strobilurin fungicides. No significant differences in total tuber yield based on N fertility were observed, although the high N rate decreased disease in Russet Burbank control plots in 2004. Due to an absence of early blight in 2003, the increase in Russet Burbank yield may be attributed to the physiological and developmental alterations brought about by strobilurin products in treated plants. In 2004, early blight was severe in inoculated control plots, but it was significantly suppressed in plots having received azoxystrobin or pyraclostrobin, regardless of the cultivar type or fertility regime. Therefore, to prevent unnecessary N inputs, growers need to supply only the necessary N amount to optimize tuber yields and manage early blight with fungicides.

scholarly journals Progeny of Selfed Plants from Tomato Breeding Line ‘NC1 Grape’ Overexpressing Mannitol Dehydrogenase (MTD) Have Increased Resistance to the Early Blight Fungus, Alternaria solani

2015 ◽  
Vol 16 (3) ◽  
pp. 115-117 ◽  
Author(s):  
Takshay K. Patel ◽  
Sergei F. Krasnyanski ◽  
George C. Allen ◽  
Frank J. Louws ◽  
Dilip R. Panthee ◽  
...  
Keyword(s):  
Early Blight ◽  
Alternaria Solani ◽  
Gray Mold ◽  
Post Inoculation ◽  
Breeding Line ◽  
Infection Rates ◽  
Mannitol Dehydrogenase ◽  
General Utility ◽  
Whole Plant ◽  
Tomato Breeding

Reactive oxygen species (ROS) made by plants in response to pathogen infection not only initiate local and systemic defenses, they are also antimicrobial. A number of fungi are hypothesized to secrete the antioxidant mannitol to protect against this antimicrobial ROS during infection. This hypothesis is supported by reports that overexpression of the mannitol catabolic enzyme mannitol dehydrogenase (MTD) in plants increases resistance to mannitol-secreting pathogens like Botrytis cinerea and Alternaria alternata. To extend this hypothesis and test the general utility of this approach, we overexpressed celery MTD in a tomato breeding line (NC1 Grape) currently used in our program. Although we reported earlier that MTD overexpression provides resistance to Botrytis gray mold in a greenhouse tomato, this is the first report of overexpression in an elite breeding variety providing heritable, whole-plant resistance to A. solani (tomato early blight). In this study, progeny from a high-MTD-expressing line had infection rates <65% those of nontransformed plants, and transformants outgrew infection by 7 days post-inoculation. Finally, our results suggest that screening for higher innate MTD expression in plants, rather than screening solely for the presence of the Mtd gene, might be a more effective way to identify parental lines for use in conventional breeding of early blight resistance. Accepted for publication 7 August 2015. Published 14 August 2015.

scholarly journals Effect of biotherapic of Alternaria solani on the early blight of tomato-plant and the in vitro development of the fungus

2021 ◽  
Vol 9 (33) ◽  
pp. 147-155
Author(s):  
Solange Monteiro de Toledo Piza Gomes Carneiro ◽  
Euclides Davidson Bueno Romano ◽  
Erika Pignoni ◽  
Marcus Zulian Teixeira ◽  
Maria Elizabeth da Costa Vasconcelos ◽  
...  
Keyword(s):  
Culture Medium ◽  
Early Blight ◽  
Alternaria Solani ◽  
Wide Distribution ◽  
Tomato Plants ◽  
Factors Affecting ◽  
In Vitro Development ◽  
Significant Difference ◽  
Vitro Development

Background: homeopathy is a means permitted in organic agriculture to control disease and plagues; biotherapics are a practical means for farmers to intervene on the health of plants in agro-ecological systems of production. Tomato-plants can be affected by several diseases, one of the most significant ones in Brazil is early blight, caused by fungus Alternaria solani, due to the damage it causes and its wide distribution in the country. Aims: to establish whether a biotherapic of A. solani may interfere on the in vitro development of the fungus and whether it affects the severity of early blight on tomato-plants in greenhouse. Methods: the effect of the biotherapic on the fungus was evaluated through the percentage of germinated spores under microscope and the growth of colonies in a culture medium. Treatments used were: biotherapic 26cH, 27cH, 28cH, 29cH and 30cH; sterilized distilled water; and diluted and agitated hydroalcoholic solution. The effect of the biotherapic on the development of disease was evaluated in 4 experiments in greenhouse. Plants were kept in vases and subjected to artificial inoculation of the fungus after the application of treatments. Evaluation of disease was carried out through diagrammatic scale. Results: no treatment affected the germination of spores or the development of fungus colonies in the culture medium. In the first test, treatment 26cH differed from water in Tukey’s test at 5% but did not differed from diluted and agitated hydroalcoholic solution. In the second test, treatments 27cH and 28cH showed significant difference from both water and hydroalcoholic solution with an average control of disease of 57% and 62% respectively. The other 2 tests did nor exhibit any significant effect. Conclusions: there was no direct effect of the biotherapic on the fungus, but there was an effect on the severity of the disease. Factors affecting the efficiency of the biotherapic must be better understood before it can be recommended to farmers for the management of early blight in tomato-plants.

scholarly journals Aerial Concentrations of Pathogens Causing Early Blight and Brown Spot Within Susceptible Potato Fields

2019 ◽  
Vol 109 (8) ◽  
pp. 1425-1432 ◽  
Author(s):  
Shunping Ding ◽  
Douglas I. Rouse ◽  
Kiana Meinholz ◽  
Amanda J. Gevens
Keyword(s):  
Host Range ◽  
Early Blight ◽  
Potato Crop ◽  
Alternaria Solani ◽  
Sole Source ◽  
Brown Spot ◽  
Broad Host Range ◽  
Long Distance ◽  
Similar Disease ◽  
Plant Families

Early blight caused by Alternaria solani and brown spot caused by A. alternata are two common foliar diseases of potato, with early blight typically predominating in incidence and severity. Renewed interest in these two diseases has arisen as a result of notable differences in fungicide resistance profiles of the pathogens and inconsistent outcomes of disease management tactics. The pathogens share similar disease cycles, but they differ in the shape and size of their conidia. A. solani has a host range that includes just the Solanaceae, whereas A. alternata has a broad host range spanning numerous plant families. Such differences may result in differences in dispersal of the pathogens and subsequently influence epidemiology and management outcomes. In the commercial potato fields investigated in this study, the aerial conidial concentrations of A. solani and A. alternata differed significantly, with those of A. alternata conidia being higher in number and more variable than those of A. solani. The aerial conidial concentration of A. solani almost always significantly decreased with height (0 to 3 m above the canopy), whereas such a decrease was only observed for 4 of 12 days for A. alternata. The atmospheric concentrations of A. alternata were higher than those of A. solani at both upwind and downwind edges of the field (P < 0.0001), indicating more potential for long-distance dispersal. A higher aerial concentration of conidia at the downwind than the upwind location was observed for A. solani (P < 0.05), whereas overall no such effect was observed for A. alternata. This indicated that the potato fields investigated were likely the source of A. solani conidia, but they may not be the sole source of A. alternata. Results are consistent with inoculum of A. solani coming primarily from within the potato crop, whereas that of A. alternata may be generated from diverse plant sources across the landscape.

scholarly journals Spatial and Temporal Sensitivity of Alternaria Species Associated With Potato Foliar Diseases to Demethylation Inhibiting and Anilino-Pyrimidine Fungicides

Plant Disease ◽  
2016 ◽  
Vol 100 (9) ◽  
pp. 1848-1857 ◽  
Author(s):  
D. L. Fonseka ◽  
N. C. Gudmestad
Keyword(s):  
Fungal Growth ◽  
Alternaria Solani ◽  
Potato Production ◽  
Brown Spot ◽  
Intrinsic Activity ◽  
In Vitro Assays ◽  
Baseline Sensitivity ◽  
Foliar Diseases

Early blight and brown spot, caused by Alternaria solani and Alternaria alternata, respectively, are important foliar diseases of potato, affecting both tuber yield and quality. Most of the commercial cultivars lack resistance; therefore, the application of foliar fungicides remains a primary disease management strategy. Baseline sensitivities of A. solani to difenoconazole and metconazole (demethylation inhibitors) using mycelial growth assay exhibited similar intrinsic activity against the pathogen with mean EC50 (the effective concentration at which the fungal growth is inhibited by 50%) values of 0.09 μg/ml. However, the sensitivity of individual baseline A. solani isolates to each fungicide varied substantially, resulting in very low and nonsignificant correlation coefficients among fungicides. Mean EC50 values for baseline A. alternata isolates in response to difenoconazole and metconazole were 0.14 and 0.26 μg/ml, respectively. The sensitivity of the majority of A. solani and A. alternata isolates collected from 2010 to 2014 from various potato production states was consistent with baseline isolates, therefore, these potato pathogens remain sensitive to the two demethylation inhibitor chemistries used to manage it. Baseline sensitivity assays of pyrimethanil (anilino-pyrimidine) also indicated great intrinsic activity against both foliar pathogens with mean EC50 values of 0.44 and 0.35 μg/ml for A. solani and A. alternata, respectively. Although A. alternata remains largely sensitive to pyrimethanil, 6 out of 245 A. solani isolates collected from 2010 to 2014 exhibited reduced-sensitivity to the fungicide in in vitro assays. Reduced-sensitive isolates were not controlled at most pyrimethanil doses except at 100 μg/ml in greenhouse in vivo efficacy tests. These chemistries remain valuable options for fungicide rotation programs in areas of high disease pressure.

scholarly journals Distribution and Stability of Quinone Outside Inhibitor Fungicide Resistance in Populations of Potato Pathogenic Alternaria spp. in Wisconsin

Plant Disease ◽  
2019 ◽  
Vol 103 (8) ◽  
pp. 2033-2040 ◽  
Author(s):  
Shunping Ding ◽  
Dennis A. Halterman ◽  
Kiana Meinholz ◽  
Amanda J. Gevens
Keyword(s):  
Cytochrome B ◽  
Point Mutations ◽  
Alternaria Solani ◽  
Cytochrome B Gene ◽  
Brown Spot ◽  
Qoi Fungicides ◽  
Quinone Outside Inhibitor ◽  
Before And After ◽  
Pathogen Populations ◽  
Qoi Resistance

Quinone outside inhibitor (QoI) fungicides have been an important class in managing potato early blight caused by Alternaria solani and brown spot caused by A. alternata. Because of the single-site mode of action character of QoI fungicides, which are relied on for management of diseases in Wisconsin, and the abundant asexual conidia production of the Alternaria species, pathogen isolates with QoI resistance have been detected after just a few years of QoI fungicide usage in commercial production fields. Resistance to QoIs has been attributed to amino acid substitutions F129L and G143A in cytochrome b of A. solani and A. alternata, respectively, as a result of point mutations. The aim of this study was to assess Alternaria populations in Wisconsin for QoI resistance before and after fungicide applications in order to evaluate resistance stability. A TaqMan single nucleotide polymorphism genotyping assay was designed based on the sequences of the cytochrome b gene from Alternaria isolates collected in Wisconsin to profile QoI resistance in Alternaria populations as well as to explore factors that may influence frequency of QoI resistance in the pathogen populations. This assay successfully identified the mutations conferring QoI resistance in isolates collected from four locations each year from 2015 to 2017. During the course of this study, the frequency of A. solani isolates with the F129L mutation was consistently high and showed primarily the TTA mutation type. The frequency of A. alternata isolates with the G143A mutation started relatively low and increased at the end of the production season in each year (P = 0.0109, P = 0.2083, and P = 0.0159). A potato field managed without use of QoI fungicides showed a significantly lower (P < 0.05) frequency of A. alternata isolates carrying G143A than conventionally managed potato fields. The overall frequency of A. alternata isolates carrying G143A in the four locations was similar over the 3 years (P = 0.2971). The QoI resistance characteristics of the isolates were stable even when QoI selection pressure was removed for at least five subculture transfers, and the mutation types of codons 129 and 143 in the cytochrome b gene in A. solani and A. alternata, respectively, remained the same. This indicated that the application of QoIs in the field is not the sole factor responsible for the variation of the frequency of QoI resistance in the pathogen populations.

Correlation coefficient between early blight severity, infection rates and meteorological factors in potato under different fungicidal spray

2018 ◽  
Vol 5 (01) ◽  
Author(s):  
AJAY M. KUMAR ◽  
S. K. SINGH ◽  
NARENDER KUMAR ◽  
VIPIN KUMAR ◽  
MAHESH SINGH ◽  
...  
Keyword(s):  
Minimum Temperature ◽  
Early Blight ◽  
Alternaria Solani ◽  
Potato Production ◽  
Significant Negative Correlation ◽  
Maximum Temperature ◽  
Progress Curve ◽  
Severe Constraint ◽  
Blight Disease ◽  
Year 2013

Early blight caused by Alternaria solani is a severe constraint in potato production. The severity of this disease has been increasing day by day for last few years in India due to changes in weather. Disease severity and area under disease progress curve (AUDPC) was recorded in each treatment plot. The early blight disease had significant negative correlation with maximum relative humidity during 2012-13 and in year 2013-14 minimum temperature was significantly correlated. The severity of early blight showed significant positive correlation with maximum temperature and highly significant positive correlations with sun shine hours in year 2013-14 in all tested treatments. The study showed that minimum temperature and rainfall revealed negative but non-significant correlation in all treatments except untreated control in year 2012-13. The maximum tuber yield 223.70 and 222.00 q/ha in first and second years, respectively, were recorded with spray of Fenamidone @ 0.2% at disease initiation and 2nd spray of Mancozeb @ 0.25% followed by Mancozeb @ 0.25% at 15 days intervals in both respective years.

scholarly journals Shift in Sensitivity of Alternaria solani in Response to QoI Fungicides

Plant Disease ◽  
2004 ◽  
Vol 88 (2) ◽  
pp. 181-187 ◽  
Author(s):  
J. S. Pasche ◽  
C. M. Wharam ◽  
N. C. Gudmestad
Keyword(s):  
Disease Severity ◽  
Spore Germination ◽  
Early Blight ◽  
Alternaria Solani ◽  
Baseline Sensitivity ◽  
Qoi Fungicides ◽  
Cross Sensitivity ◽  
Significant Difference

Isolates of Alternaria solani, cause of potato early blight, collected in 1998 through 2001 from various potato growing areas across the midwestern United States, were tested for sensitivity to azoxystrobin. Isolates collected in 1998, prior to the introduction of azoxystrobin, were tested to establish the baseline sensitivity of the fungus to this fungicide. Isolates collected in subsequent years, not necessarily from the same sites as baseline isolates, were tested to determine if populations of A. solani had become less sensitive to azoxystrobin. Azoxystrobin sensitivity was determined utilizing an in vitro spore germination assay. The effective fungicide concentration that inhibited spore germination by 50% (EC50) was determined for each isolate. There was no significant difference in mean EC50 values between baseline isolates and all other isolates collected through 1999. Mean azoxystrobin EC50 values of A. solani isolates collected in 2000 and 2001 were significantly higher compared with means from previous years, and mean azoxystrobin EC50 values from 2001 were significantly higher than means from isolates collected in 2000. A subset of 54 A. solani isolates was evaluated in vitro for cross-sensitivity to pyraclostrobin and trifloxystrobin. A highly significant and strong correlation among the isolates tested for fungicide cross-sensitivity was detected between azoxystrobin and pyraclostrobin; however, the correlation between azoxystrobin and trifloxystrobin, and between trifloxystrobin and pyraclostrobin, was significant but weak. A second subset of five isolates was chosen for in vivo assessment of azoxystrobin, pyraclostrobin, and trifloxystrobin sensitivity. Disease severity on plants treated with azoxystrobin and pyraclostrobin was significantly greater with reduced-sensitive A. solani isolates compared with sensitive isolates. Disease severity was not statistically different between azoxystrobin reduced-sensitive and sensitive A. solani isolates on plants treated with trifloxystrobin. This is the first report of a shift in sensitivity to QoI fungicides in a fungus possessing only an anamorphic stage.

Sign in / Sign up

Export Citation Format

Share Document