scholarly journals Isolation and Identification of the Fungus Colletotrichum cordylinicola Causing Anthracnose Disease on Cordyline fruticosa in Florida

HortScience ◽  
2014 ◽  
Vol 49 (7) ◽  
pp. 911-916 ◽  
Author(s):  
Kalpana Sharma ◽  
Erica Goss ◽  
Ariena H.C. van Bruggen
Keyword(s):  
Regression Line ◽  
Aerial Mycelium ◽  
The United States ◽  
Isolation And Identification ◽  
Disease Progress ◽  
Progress Curve ◽  
Latently Infected ◽  
Cordyline Fruticosa ◽  
Mean Size ◽  
Colony Color

Imported Hawaiian Ti Cordyline plants (Cordyline fruticosa) ‘Tipsy Pink’ with anthracnose symptoms were found in Gainesville, FL, in 2013. A Colletotrichum spp. was isolated from symptomatic Cordyline plants and Koch’s postulates were fulfilled. The colony color on acidified potato dextrose agar (PDA) was orange with slight shades of pink and light gray aerial mycelium. Sclerotia and setae were absent. Conidia were one-celled, hyaline, guttulate, and cylindrical with round ends. The mean size of the conidia was 14.7 × 5.0 μm and ranged from 12.5 to 17.5 × 3.8 to 7.5 μm. Polymerase chain reaction (PCR) was performed on the internal transcribed space (ITS) and 28S rDNA regions of the isolate, and the sequences were compared with those of Colletotrichum spp. in GenBank. Sequence analysis indicated that the isolate belonged to C. cordylinicola. This is the first report of C. cordylinicola on C. fruticosa in Florida and the United States. Anthracnose symptoms developed on healthy-looking, latently infected Hawaiian Ti plants within 2 to 3 months, and 34% to 44% of the non-inoculated plants became diseased in 3 months. Reactions of several Dracaena and Cordyline species and varieties including Hawaiian Ti to C. cordylinicola were assessed. Several Dracaena and Cordyline species and varieties including Hawaiian Ti exhibited a differential response when inoculated with C. cordylinicola, but none of them was resistant. Hawaiian Ti was the most and lucky bamboo (Dracaena sanderiana) the least susceptible [area under the disease progress curve (AUDPC) = 71 vs. 10 cm2·d–1] to C. cordylinicola. The slope of the log-transformed disease progress regression line was steepest on Hawaiian Ti and D. marginata variety ‘Colorama’ plants, intermediate on varieties ‘Tarzan’ and ‘Magenta’, and least on lucky bamboo [slope = 0.046, 0.044, 0.036, and 0.034 vs. 0.020 log(cm2 + 1)/d, respectively, with a mean se of 0.0006].

scholarly journals Evaluation of Poinsettia Cultivars for Susceptibility to Powdery Mildew

HortScience ◽  
1997 ◽  
Vol 32 (2) ◽  
pp. 259-261 ◽  
Author(s):  
G.J. Celio ◽  
M.K. Hausbeck
Keyword(s):  
United States ◽  
Powdery Mildew ◽  
The United States ◽  
The Other ◽  
Euphorbia Pulcherrima ◽  
Disease Progress Curve ◽  
Disease Progress ◽  
Progress Curve

Powdery mildew (Oidium spp. Link) on poinsettias (Euphorbia pulcherrima Willd. ex Klotzsch) growing in commercial greenhouses was first observed in the United States in 1990. Susceptibility of poinsettia cultivars (`Freedom Red', `Hot Pink', `Jingle Bells 3', `Pink Peppermint', `Red Sails', `Supjibi Red', `Topwhite', `V-14 Glory', `V-14 Pink', `V-14 White', `V-17 Angelika White') to powdery mildew was investigated using 8- to 10-week-old poinsettias with mature bracts. Area under the incidence of disease progress curve was used to express the incidence of bracts infected over 31 d after inoculation. Three cultivars with red bracts (`Freedom Red', `Supjibi Red', `Red Sails') had significantly more infection than the other cultivars in both experiments, while one cultivar with white bracts (`V-17 Angelika White') had significantly less infection.

scholarly journals Field Evaluations of Leaf Spot Resistance and Yield in Peanut Genotypes in the United States and Bolivia

Plant Disease ◽  
2011 ◽  
Vol 95 (3) ◽  
pp. 263-268 ◽  
Author(s):  
S. K. Gremillion ◽  
A. K. Culbreath ◽  
D. W. Gorbet ◽  
B. G. Mullinix ◽  
R. N. Pittman ◽  
...  
Keyword(s):  
United States ◽  
Disease Resistance ◽  
Leaf Spot ◽  
Field Experiments ◽  
Disease Incidence ◽  
The United States ◽  
Yield Potential ◽  
Cercospora Arachidicola ◽  
Breeding Lines ◽  
Progress Curve

Field experiments were conducted in 2002 to 2006 to characterize yield potential and disease resistance in the Bolivian landrace peanut (Arachis hypogaea) cv. Bayo Grande, and breeding lines developed from crosses of Bayo Grande and U.S. cv. Florida MDR-98. Diseases of interest included early leaf spot, caused by the fungus Cercospora arachidicola, and late leaf spot, caused by the fungus Cercosporidium personatum. Bayo Grande, MDR-98, and three breeding lines, along with U.S. cvs. C-99R and Georgia Green, were included in split-plot field experiments in six locations across the United States and Bolivia. Whole-plot treatments consisted of two tebuconazole applications and a nontreated control. Genotypes were the subplot treatments. Area under the disease progress curve (AUDPC) for percent defoliation due to leaf spot was lower for Bayo Grande and all breeding lines than for Georgia Green at all U.S. locations across years. AUDPC for disease incidence from one U.S. location indicated similar results. Severity of leaf spot epidemics and relative effects of the genotypes were less consistent in the Bolivian experiments. In Bolivia, there were no indications of greater levels of disease resistance in any of the breeding lines than in Bayo Grande. In the United States, yields of Bayo Grande and the breeding lines were greater than those of the other genotypes in 1 of 2 years. In Bolivia, low disease intensity resulted in the highest yields in Georgia Green, while high disease intensity resulted in comparable yields among the breeding lines, MDR-98, and C-99R. Leaf spot suppression by tebuconazole was greater in Bolivia than in the United States. This result indicates a possible higher level of fungicide resistance in the U.S. population of leaf spot pathogens. Overall, data from this study suggest that Bayo Grande and the breeding lines may be desirable germplasm for U.S. and Bolivian breeding programs or production.

scholarly journals Management of Daylily Rust With Different Fungicides and Fungicide Combinations

2017 ◽  
Vol 18 (3) ◽  
pp. 162-165 ◽  
Author(s):  
Robert S. Emmitt ◽  
James W. Buck
Keyword(s):  
United States ◽  
Disease Management ◽  
Disease Severity ◽  
Low Cost ◽  
Single Application ◽  
Southeast United States ◽  
Disease Progress Curve ◽  
Disease Progress ◽  
Progress Curve ◽  
Disease Pressure

Production nurseries and daylily hybridizers in the southeast United States rely on the use of fungicides to manage daylily rust, caused by the fungus Puccinia hemerocallidis. Foliar sprays of pyraclostrobin, flutolanil, tebuconazole, myclobutanil, chlorothalonil, mancozeb, pyraclostrobin + boscalid, flutolanil + tebuconazole, flutolanil + myclobutanil, flutolanil + chlorothalonil, and flutolanil + mancozeb applied on 14-day intervals, and a nontreated control, were evaluated under high disease pressure at three locations in Griffin, GA, in 2015. Tebuconazole or the tebuconazole + flutolanil treatment consistently had the lowest area under the disease progress curve (AUDPC) of the treatments. The addition of flutolanil to chlorothalonil or mancozeb did not improve rust control and no difference in disease severity was observed in any treatment containing contact fungicides on all assessment dates. Single application costs ranged from $10.21 to $95.96 with tebuconazole providing excellent disease management at a relatively low cost per application ($13.90).

scholarly journals Estimation of a Time-varying Apparent Infection Rate from Plant Disease Progress Curves: A Particle Filter Approach

2019 ◽  
Author(s):  
Kaique dos S Alves ◽  
Willian B Moraes ◽  
Wellington B da Silva ◽  
Emerson M Del Ponte
Keyword(s):  
Particle Filter ◽  
Infection Rate ◽  
Plant Disease ◽  
Host Susceptibility ◽  
Time Varying ◽  
Factors Affecting ◽  
Initial Inoculum ◽  
Disease Progress ◽  
Progress Curve ◽  
Apparent Infection Rate

AbstractThe parameters of the simplest (two-parameter) epidemiological models that best fit plant disease progress curve (DPC) data are the surrogate for initial inoculum (y0) and the (constant) apparent infection rate (r), both being useful for understanding, predicting and comparing epidemics. The assumption thatris constant is not reasonable and fluctuations are expected due to systematic changes in factors affecting infection (e.g. weather favorability, host susceptibility, etc.), thus leading to a time-varyingr, orr(t). An arrangement of these models (e.g. logistic, monomolecular, etc.) can be used to obtainrbetween two time points, given the disease (y) data are available. We evaluated a data assimilation technique, Particle Filter (PF), as an alternative method for estimatingr(t). Synthetic DPC data for a hypothetical polycyclic epidemics were simulated using the logistic differential equation for scenarios that combined five patterns ofr(t) (constant, increasing, decreasing, random or sinusoidal); five increasing time assessment interval (Δt= 1, 3, 5, 7 or 9 time units - t.u.); and two levels of noise (α = 0.1 or 0.25) assigned toy(t). The analyses of 50 simulated 60-t.u. DPCs showed that the errors of PF-derivedwere lower (RMSE < 0.05) for Δt< 5 t.u. and least affected by the presence of noise in the measure compared with the logit-derivedr(t). The ability to more accurately estimater(t) using the novel method may be useful to increase knowledge of field epidemics and identify within-season drivers that may explainr(t) behaviour.

scholarly journals Isolation and Identification of Rickettsia massiliae from Rhipicephalus sanguineus Ticks Collected in Arizona

2006 ◽  
Vol 72 (8) ◽  
pp. 5569-5577 ◽  
Author(s):  
Marina E. Eremeeva ◽  
Elizabeth A. Bosserman ◽  
Linda J. Demma ◽  
Maria L. Zambrano ◽  
Dianna M. Blau ◽  
...  
Keyword(s):  
Spotted Fever ◽  
Rhipicephalus Sanguineus ◽  
Vero Cells ◽  
The United States ◽  
Spotted Fever Group ◽  
Pcr Assay ◽  
Isolation And Identification ◽  
Cytotoxic Effects ◽  
Rickettsia Massiliae ◽  
Genotypic Characteristics

ABSTRACT Twenty Rhipicephalus sanguineus ticks collected in eastern Arizona were tested by PCR assay to establish their infection rate with spotted fever group rickettsiae. With a nested PCR assay which detects a fragment of the Rickettsia genus-specific 17-kDa antigen gene (htrA), five ticks (25%) were found to contain rickettsial DNA. One rickettsial isolate was obtained from these ticks by inoculating a suspension of a triturated tick into monolayers of Vero E6 monkey kidney cells and XTC-2 clawed toad cells, and its cell culture and genotypic characteristics were determined. Fragments of the 16S rRNA, GltA, rOmpA, rOmpB, and Sca4 genes had 100%, 100%, 99%, 99%, and 99%, respectively, nucleotide similarity to Rickettsia massiliae strain Bar29, previously isolated from R. sanguineus in Catalonia, Spain (L. Beati et al., J. Clin. Microbiol. 34:2688-2694, 1996). The new isolate, AZT80, does not elicit cytotoxic effects in Vero cells and causes a persistent infection in XTC-2 cells. The AZT80 strain is susceptible to doxycycline but resistant to rifampin and erythromycin. Whether R. massiliae AZT80 is pathogenic or infectious for dogs and humans or can cause seroconversion to spotted fever group antigens in the United States is unknown.

Comparative Performance of Sanitizers in Managing Plant-to-plant Transfer and Postharvest Infection of Calonectria pseudonaviculata and Pseudonectria foliicola on Boxwood

Plant Disease ◽  
2021 ◽  
Author(s):  
Ravi Bika ◽  
Warren Copes ◽  
Fulya Baysal-Gurel
Keyword(s):  
Shelf Life ◽  
Disease Severity ◽  
Ammonium Compound ◽  
Conidial Suspension ◽  
Rooted Cuttings ◽  
Disease Progress ◽  
Progress Curve ◽  
Significant Difference ◽  
Plant Transfer ◽  
Blight Disease

Calonectria pseudonaviculata and Pseudonectria foliicola causing the infamous ‘boxwood blight’ and ‘Volutella blight’, respectively, are a constant threat to the boxwood production and cut boxwood greenery market. Both pathogens cause significant economic loss to all parties (growers, retailer, and customers) in the horticultural chain. The objective of this study was to evaluate efficacy of disinfesting chemicals [quaternary ammonium compound (QAC), peroxy, acid, alcohol, chlorine, cleaner] in preventing plant-to-plant transfer of C. pseudonaviculata and P. foliicola via cutting tools, as well as reduction of postharvest boxwood blight and Volutella blight disease severity in harvested boxwood greenery. First, an in vitro study was conducted to select products and doses that completely or near-completely inhibited conidial germination of C. pseudonaviculata and P. foliicola. The selected treatments were also tested for their ability to reduce plant-to-plant transfer of C. pseudonaviculata and P. foliicola and manage postharvest boxwood blight and Volutella blight in boxwood cuttings. For the plant-to-plant transfer study, Felco 19 shears were used as a tool for mechanical transfer of fungal conidia. The blades of Felco 19 shears were exposed to a conidial suspension of C. pseudonaviculata or P. foliicola by cutting a 1 cm diameter cotton roll that had been dipped into a fungal suspension. Disease-free boxwood rooted cuttings (10 cm height) were pruned with the contaminated shears. The Felco 19 shears were equipped with a mounted miniature sprayer connected to a pressurized reservoir of treatment solution that automatically sprayed the blade and plant surface while cutting. The influence of accumulated sap on the shear blade was studied through 1- or 10-cut pruning variable on test plants and screened for the efficacy of treatments. Then, the boxwood rooted cuttings were transplanted and incubated in room conditions (21 °C, 60% RH) with 12 h of fluorescent light; data evaluation on disease severity was done weekly for a month. Disease progress [area under disease progress curve (AUDPC)] was calculated. In another study, postharvest dip application treatments were used for the management of postharvest boxwood blight or Volutella blight on boxwood cuttings. The harvested boxwood cuttings were inoculated with a conidial suspension of C. pseudonaviculata or P. foliicola, then dipped into treatment solution 3 days afterwards. The treated boxwood cuttings were kept in room conditions, and boxwood blight or Volutella blight disease severity as well as marketability (postharvest shelf life) assessed every 2 days for 1 week. A significant difference between treatments was observed for reduction of boxwood blight or Volutella blight severity and AUDPC. The treatments (ODD + DoD + DdD + DB)AC [Simple Green D Pro 5], 2 propanol + DDAC (0.12%) [KleenGrow], and DBAC + DEAC [GreenShield] were the most effective in reducing the plant to plant transfer of boxwood blight and Volutella blight when pruned with contaminated Felco 19 shears. In addition to the three effective treatments above, acetic acid (2.5%) [Vinegar], 2-propanol + DDAC (0.06%), sodium hypochlorite (Clorox) and potassium peroxymonosulfate + NaCl (2%) [Virkon] were effective in reducing postharvest boxwood blight whereas DBAC + DBAC [Lysol all-purpose cleaner], ethanol [70% (Ethyl alcohol)] and DDAC +DBAC [Simple Green D Pro 3 plus] were effective in reducing Volutella blight disease severity and AUDPC, and also maintained better quality and longer postharvest shelf life of boxwood cuttings when applied as a dip treatment. The longer postharvest shelf life of boxwood cuttings noted may be attributed to reduced disease severity and AUDPC resulting in healthy boxwood cuttings.

scholarly journals Temporal progress of southern rust in maize under different environmental conditions

2003 ◽  
Vol 28 (3) ◽  
pp. 273-278 ◽  
Author(s):  
Cláudia V. Godoy ◽  
Lílian Amorim ◽  
Armando Bergamin Filho ◽  
Herbert P. Silva ◽  
Willian J. Silva ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Disease Severity ◽  
Logistic Model ◽  
Inflection Point ◽  
Gompertz Model ◽  
Disease Progress Curve ◽  
Disease Progress ◽  
Progress Curve ◽  
Puccinia Polysora ◽  
The Mean

The progress of the severity of southern rust in maize (Zea mays) caused by Puccinia polysora was quantified in staggered plantings in different geographical areas in Brazil, from October to May, over two years (1995-1996 and 1996-1997). The logistic model, fitted to the data, better described the disease progress curves than the Gompertz model. Four components of the disease progress curves (maximum disease severity; area under the disease progress curve, AUDPC; area under the disease progress curve around the inflection point, AUDPCi; and epidemic rate) were used to compare the epidemics in different areas and at different times of planting. The AUDPC, AUDPCi, and the epidemic rate were analyzed in relation to the weather (temperature, relative humidity, hours of relative humidity >90%, and rainfall) and recorded during the trials. Disease severity reached levels greater than 30% in Piracicaba and Guaíra in the plantings between December and January. Lower values of AUDPC occurred in later plantings at both locations. The epidemic rate was positively correlated (P < 0.05) with the mean daily temperatures and negatively correlated with hours of relative humidity >90%. The AUDPC was not correlated with any weather variable. The AUDPCi was negatively related to both variables connected to humidity, but not to rain. Long periods (mostly >13 h day-1) of relative humidity >90% (that corresponded to leaf wetness) occurred in Castro. Severity of southern rust in maize has always been low in Castro, thus the negative correlations between disease and the two humidity variables.

scholarly journals Fungicides for Control of Downy Mildew on Pickling Cucumber in Michigan

2019 ◽  
Vol 20 (3) ◽  
pp. 165-169 ◽  
Author(s):  
Katelyn E. Goldenhar ◽  
Mary K. Hausbeck
Keyword(s):  
Downy Mildew ◽  
Untreated Control ◽  
Field Studies ◽  
Pseudoperonospora Cubensis ◽  
Relative Area ◽  
Disease Progress Curve ◽  
Cucurbit Downy Mildew ◽  
Disease Progress ◽  
Pickling Cucumber ◽  
Progress Curve

Michigan growers rely on fungicides to limit cucurbit downy mildew (CDM), incited by Pseudoperonospora cubensis; resistance of the pathogen to fungicides is a concern. We evaluated fungicides against CDM in Michigan field studies from 2015 to 2017. According to the relative area under the disease progress curve (rAUDPC), in 2015, mandipropamid, propamocarb, fluxapyroxad/pyraclostrobin, copper octanoate, and dimethomorph resulted in disease levels similar to the control. These treatments, along with cymoxanil, were similar to the control in 2016. Fungicides that were ineffective during 2015 and 2016 did not limit CDM in 2017. Famoxadone/cymoxanil and fluopicolide did not limit CDM in 2017. Each year, the following treatments were similar for disease based on rAUDPC data: oxathiapiprolin applied alone or premixed with chlorothalonil or mandipropamid, ametoctradin/dimethomorph, fluazinam, mancozeb/zoxamide, cyazofamid, and ethaboxam. An exception occurred in 2017, when ethaboxam was less effective than fluazinam, oxathiapiprolin/chlorothalonil, and oxathiapiprolin/mandipropamid. Mancozeb and chlorothalonil treatments were similar in 2015 and 2017, according to rAUDPC data. In 2017, yields were increased for oxathiapiprolin/chlorothalonil, oxathiapiprolin/mandipropamid, mancozeb, ametoctradin/dimethomorph, mancozeb/zoxamide, ethaboxam, cyazofamid, chlorothalonil, and fluazinam compared with the untreated control.

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