Susceptibility of eight potato cultivars to tuber infection by Phytophthora erythroseptica and Pythium ultimum and its relationship to mefenoxam-mediated control of pink rot and leak

2008 ◽  
Vol 152 (2) ◽  
pp. 189-199 ◽  
Author(s):  
R.J. Taylor ◽  
J.S. Pasche ◽  
N.C. Gudmestad
Keyword(s):  
Pythium Ultimum ◽  
Potato Cultivars ◽  
Pink Rot ◽  
Tuber Infection ◽  
Phytophthora Erythroseptica

scholarly journals A Rapid Technique for the Evaluation of Potato Germ Plasm for Susceptibility to Pink Rot

Plant Disease ◽  
2001 ◽  
Vol 85 (8) ◽  
pp. 833-837 ◽  
Author(s):  
R. D. Peters ◽  
A. V. Sturz
Keyword(s):  
Prince Edward Island ◽  
Germ Plasm ◽  
Potato Cultivars ◽  
Reliable Technique ◽  
Disease Symptoms ◽  
Disease Response ◽  
Pink Rot ◽  
Phytophthora Erythroseptica ◽  
Screening Protocol ◽  
Disease Free

Disease-free plantlets of 20 potato cultivars commonly grown in Prince Edward Island were inoculated with zoospore suspensions of Phytophthora erythroseptica, the causal agent of pink rot, to determine disease response. All inoculated cultivars developed disease symptoms relative to noninoculated controls, but disease severity differed significantly (P = 0.05) among cultivars. Plantlets of the cultivars Goldrush and Yukon Gold were consistently the most susceptible to the disease, whereas plantlets of cultivars Butte and Russet Burbank were the least susceptible. Most of the cultivars assessed were moderately susceptible to disease. Plantlets of potato cultivars with late-season field maturity were more resistant to disease than those with early or mid-season maturity. Isolates of P. erythroseptica from diverse regions of Prince Edward Island and Maine did not differ significantly (P = 0.05) in pathogenicity. The screening protocol described was a reliable technique to determine the relative resistance of nontuber potato germ plasm to disease, resulting from infection with P. erythroseptica.

scholarly journals Sensitivity of North American Isolates of Phytophthora erythroseptica and Pythium ultimum to Mefenoxam (Metalaxyl)

Plant Disease ◽  
2002 ◽  
Vol 86 (7) ◽  
pp. 797-802 ◽  
Author(s):  
R. J. Taylor ◽  
B. Salas ◽  
G. A. Secor ◽  
V. Rivera ◽  
N. C. Gudmestad
Keyword(s):  
Pythium Ultimum ◽  
Effective Management ◽  
Potato Tubers ◽  
Pink Rot ◽  
Phytophthora Erythroseptica ◽  
Disease Management Strategy ◽  
Potato Tuber Rot ◽  
Canadian Provinces ◽  
Production Areas ◽  
First Time

A 4-year study (1997 to 2000) was conducted to determine the sensitivities of the potato tuber rot pathogens, Phytophthora erythroseptica and Pythium ultimum, to mefenoxam (metalaxyl). A total of 2,277 tubers showing symptoms of “water rot” were collected from 16 states and 2 Canadian provinces. From these, 849 isolates of P. erythroseptica and 213 isolates of P. ultimum were obtained, and 805 and 190 isolates, respectively, were tested for their ability to grow on V8 medium amended at 0.01 to 100 μg/ml with fungicide. Isolates ranged widely in their responses to mefenoxam. The presence of resistant isolates (EC50 > 100 μg ml-1) of P. erythroseptica in the potato producing areas of Maine was confirmed. The presence of P. erythroseptica isolates in Idaho and Minnesota resistant to mefenoxam is reported for the first time. The proportion of P. erythroseptica isolates resistant to mefenoxam varied from 2.9 to 36.2% between 1997 and 2000. The proportion of resistant P. ultimum isolates represented only a small proportion of the isolates tested (3.7%). A single resistant P. ultimum isolate was recovered from Washington, whereas most of the resistant isolates obtained (5 of 7) were collected in Minnesota during the final year of the study. This is the first report of resistance in P. ultimum pathogenic to potato tubers. These observations suggest that pink rot and leak could become significant problems in the future, particularly in those areas where resistance has been detected. Our results have implications for the effective management of water rot. Monitoring the sensitivity of the pathogen population to mefenoxam in all production areas should be considered and integrated as a part of the overall disease management strategy.

scholarly journals Differences in Etiology Affect Mefenoxam Efficacy and the Control of Pink Rot and Leak Tuber Diseases of Potato

Plant Disease ◽  
2004 ◽  
Vol 88 (3) ◽  
pp. 301-307 ◽  
Author(s):  
Raymond J. Taylor ◽  
Bacilio Salas ◽  
Neil C. Gudmestad
Keyword(s):  
Foliar Application ◽  
Potato Production ◽  
Pythium Ultimum ◽  
Potato Tubers ◽  
Disease Etiology ◽  
Factors Affecting ◽  
Pink Rot ◽  
Application Rates ◽  
Phytophthora Erythroseptica ◽  
Production Areas

Data supplementing a previously published survey of North American isolates of Phytophthora erythroseptica and Pythium ultimum demonstrated that the proportion of the populations sensitive to mefenoxam remains high, 79.6 and 96.9% with EC50 sensitivities ranging from <0.01 to 0.9 µg ml-1 and <0.01 to 0.8 µg ml-1, respectively. Mefenoxam should provide control of these pathogens in most potato production areas. Factors affecting the development of pink rot and leak in potato tubers and the efficacy of mefenoxam to control these diseases with different etiologies were examined. Results confirmed that P. erythroseptica is capable of directly infecting potato tubers causing pink rot, whereas Pythium ultimum requires a wound to infect and cause leak. Mefenoxam was applied to replicated field plots as a single in-furrow application at planting, as an in-furrow application at planting followed by an additional sidedress application 3 weeks after planting, as a single foliar application when tubers were 7 to 8 mm in diameter, and as two foliar applications when the tubers were 7 to 8 mm in diameter and 14 days later. The recommended label rate plus two additional lower application rates were used with each method. For tubers challenge-inoculated after harvest, mefenoxam was found to be more effective in controlling pink rot relative to leak over all application methods. The greatest level of pink rot control (89%) was attained with the in-furrow at planting and sidedress application. All rates tested provided similar levels of control with this application method, but this method provided only a modest level of leak control (35%), and leak was not controlled by foliar applications of mefenoxam at any rate tested. In contrast, the foliar applications of mefenoxam resulted in 10 to 50% control of pink rot. Since the isolates of both pathogens were highly sensitive to me-fenoxam, disease-specific control was attributed to differences in disease etiology. Therefore, the use of mefenoxam to control pink rot in the field and storage appears to be well founded.

scholarly journals Assessment of Resistance of Tubers of Potato Cultivars to Phytophthora erythroseptica and Pythium ultimum

Plant Disease ◽  
2003 ◽  
Vol 87 (1) ◽  
pp. 91-97 ◽  
Author(s):  
Bacilio Salas ◽  
Gary A. Secor ◽  
R. J. Taylor ◽  
Neil C. Gudmestad
Keyword(s):  
Disease Management ◽  
Pythium Ultimum ◽  
Potato Cultivars ◽  
The Other ◽  
Soilborne Diseases ◽  
Russet Norkotah ◽  
Susceptibility To Infection ◽  
Phytophthora Erythroseptica ◽  
Resistance To Infection ◽  
Cultivar Susceptibility

Tubers of 34 potato cultivars were examined for their susceptibility to infection by zoospores of Phytophthora erythroseptica and mycelia of Pythium ultimum. Incidence of infected tubers (%) and penetration of rot (mm) were the parameters used to determine the susceptibility of each cultivar. Tubers of cv. Atlantic appeared to have some resistance to infection and colonization by Phytophthora erythroseptica. Cvs. Russet Norkotah and Snowden were the most susceptible to infection by P. erythroseptica. Snowden was found to be highly susceptible to P. erythroseptica, but it was the most resistant to Pythium ultimum. Cvs. FL-1625 and FL-1867 also were less susceptible to P. ultimum than the other cultivars. Cvs. Superior, Itasca, and Dark Red Norland were the most susceptible to P. ultimum. Cultivar susceptibility should be considered when making disease management decisions, particularly in fields where these soilborne diseases are a recurring problem.

scholarly journals In-Furrow Applications of Metalaxyl and Phosphite for Control of Pink Rot (Phytophthora erythroseptica) of Potato in New Brunswick, Canada

Plant Disease ◽  
2007 ◽  
Vol 91 (10) ◽  
pp. 1305-1309 ◽  
Author(s):  
Khalil I. Al-Mughrabi ◽  
Rick D. Peters ◽  
H. W. (Bud) Platt ◽  
Gilles Moreau ◽  
Appanna Vikram ◽  
...  
Keyword(s):  
New Brunswick ◽  
Disease Incidence ◽  
Field Trials ◽  
Russet Burbank ◽  
Viable Option ◽  
Potato Plants ◽  
Pink Rot ◽  
Phytophthora Erythroseptica ◽  
Sensitive Isolate ◽  
The Mean

The efficacy of metalaxyl-m (Ridomil Gold 480EC) and phosphite (Phostrol) applied at planting in-furrow against pink rot (Phytophthora erythroseptica) of potato (Solanum tuberosum) ‘Shepody’ and ‘Russet Burbank’ was evaluated in field trials conducted in 2005 and 2006 in Florenceville, New Brunswick, Canada. Inoculum made from a metalaxyl-m-sensitive isolate of P. erythroseptica from New Brunswick was applied either in-furrow as a vermiculite slurry at planting or as a zoospore drench in soils adjacent to potato plants in late August. After harvest, the number and weight of tubers showing pink rot symptoms were assessed and expressed as percentages of the total tuber number and total weight of tubers. Metalaxyl-m applied in-furrow was significantly more effective against pink rot than phosphite. The mean percentage of diseased tubers as a percentage of total tuber weight was 1.5% (2005) and 1.2% (2006) for metalaxyl-m-treated plots and 9.6% (2005) and 2.8% (2006) for phosphite-treated plots, a percentage similar to that obtained in inoculated control plots with no fungicide treatment. The mean percentage of diseased tubers expressed as a percentage of the total number of tubers was 1.7% (2005) and 1.3% (2006) for metalaxyl-m-treated plots and 10.1% (2005) and 3.1% (2006) for phosphite-treated plots. Disease incidence was significantly higher using the late-season inoculation technique (respective means in 2005 and 2006 were 9.9 and 3.8% diseased tubers, by weight, and 10.6 and 3.9%, by number) than with the in-furrow inoculation method (respective means in 2005 and 2006 were 3.3 and 0.7% by weight, and 3.7 and 1.3%, by number). The potato cv. Shepody was significantly more susceptible to pink rot (9.9 and 3.3% diseased tubers, by weight, in 2005 and 2006, respectively, and 10.6 and 3.9%, by number) than Russet Burbank (respective means in 2005 and 2006 were 3.4,% and 1.2%, by weight, and 3.7,% and 1.2%, by number). Our findings indicate that metalaxyl applied in-furrow at planting is a viable option for control of pink rot caused by metalaxyl-sensitive strains of P. erythroseptica, whereas phosphite was ineffective.

Studies on Fusarium species associated with a field planting of 'pathogen-tested' potatoes

1974 ◽  
Vol 25 (2) ◽  
pp. 293 ◽  
Author(s):  
SC Chambers ◽  
JR Millington
Keyword(s):  
Bacillus Subtilis ◽  
Fusarium Species ◽  
Streptomyces Griseus ◽  
Potato Cultivars ◽  
Experimental Site ◽  
Fusarium Infection ◽  
Tuber Infection ◽  
Soil Population

Bacillus subtilis (isolate 1-B80) and Streptomyces griseus (isolate 2-A24), both antagonistic to Fusarium species, were applied to 'pathogen-tested' cuttings of the potato cultivars Kennebec and Sequoia, and to their potting soil, before transplanting to the field. No data were obtained to indicate that either microorganism reduced Fusarium infection of tubers from these transplants. However, the Fusarium population was significantly less at 70 days in soil proximal to Sequoia transplants treated with either microorganism, and to Kennebec transplants treated with S. griseus. Tuber yields were significantly greater from Sequoia, but not from Kennebec when treated with either microorganism. Six Fusarium species were isolated from infected tubers, F. oxysporum being the commonest. In most instances, infection was confined to one tuber per plant. There was no correlation between tuber infection and stem injury, nor between tuber infection and soil population. In the laboratory, the addition of B. subtilis and S. griseus to soil from the experimental site significantly reduced estimates of the Fusarium population for 70 and 140 days respectively.

scholarly journals The Effect of Wounding, Temperature, and Inoculum on the Development of Pink Rot of Potatoes Caused by Phytophthora erythroseptica

Plant Disease ◽  
2000 ◽  
Vol 84 (12) ◽  
pp. 1327-1333 ◽  
Author(s):  
B. Salas ◽  
R. W. Stack ◽  
G. A. Secor ◽  
N. C. Gudmestad
Keyword(s):  
Infection Risk ◽  
Infected Tuber ◽  
Tuber Tissue ◽  
Inoculum Level ◽  
Inoculum Sources ◽  
Pink Rot ◽  
High Inoculum ◽  
Phytophthora Erythroseptica ◽  
Laboratory Cultures ◽  
Potential Impact

The effect of wounding, temperature, and inoculum on the development of pink rot caused by Phytophthora erythroseptica, was studied for its potential impact on postharvest infection. Tissue plugs cut from pink rot infected tubers and plugs of similar size from laboratory cultures of the pathogen were highly effective inoculum sources on wounded tubers. Severe wounding, temperatures of 15 to 25°C, and high inoculum density affected the infection risk. Regardless of source or amount of inoculum, any degree of wounding greatly increased incidence of infection of tubers by P. erythroseptica. Infections in unwounded tubers started at 15°C, whereas in wounded tubers infection started at 10°C. Incidence of pink rot was high when two or three of the factors (severe wounding, high temperature, high inoculum level) were favorable. Incidence of pink rot was intermediate when only one factor was favorable. Incidence of pink rot was low or absent without a favorable factor (no wounding, low temperature, and low inoculum), Since infected tuber tissue may serve as potential inoculum source for postharvest infection of tubers by P. erythroseptica, the removal of pink rot infected tubers at harvest is desirable. Avoidance of wounding and rapid cooling of storage bins to 10°C may also help control pink rot.

scholarly journals Effect of Application Method and Rate on Residual Efficacy of Mefenoxam and Phosphorous Acid Fungicides in the Control of Pink Rot of Potato

Plant Disease ◽  
2011 ◽  
Vol 95 (8) ◽  
pp. 997-1006 ◽  
Author(s):  
Raymond J. Taylor ◽  
Julie S. Pasche ◽  
Neil C. Gudmestad
Keyword(s):  
Irrigation System ◽  
Phosphorous Acid ◽  
Field Trials ◽  
Resistant Isolate ◽  
Challenge Inoculation ◽  
Pink Rot ◽  
Phytophthora Erythroseptica ◽  
Small Plot ◽  
Tuber Rot ◽  
Commercial Field

Experiments were conducted to examine the effectiveness of rate and method of phosphorous acid application for controlling pink rot of potato (Solanum tuberosum) caused by Phytophthora erythroseptica. Replicated small-plot and replicated split commercial field trials were established in commercial production fields in Minnesota from 2006 to 2009. Fungicides were applied in-furrow at planting, or as one, two, or three foliar applications via ground sprayer, irrigation system (chemigation), or fixed-wing aircraft. Phosphorous acid efficacy was compared to mefenoxam, the fungicide commonly utilized to manage pink rot, either by determining natural infections in the field or by inoculating eyes of harvested tubers using a mefenoxam-sensitive and -resistant isolate of P. erythroseptica via postharvest challenge inoculation. In replicated small plot trials, both in-furrow and two foliar applications of mefenoxam controlled tuber rot in the field, and significantly controlled tuber rot in storage. Phosphorous acid also reduced tuber rot in the field when applied two or three times to the foliage. Although phosphorous acid was ineffective when applied in-furrow, one, two, and three foliar applications and a postharvest application of phosphorous acid controlled mefenoxam-sensitive and -resistant isolates of P. erythroseptica during storage for 187 days, while mefenoxam failed to control the resistant isolate. In replicated split commercial field trials, two aerial applications of phosphorous acid were as effective as three applications in reducing pink rot incidence in tubers inoculated postharvest. Three aerial applications were as effective as three chemigation applications in replicated split commercial field trials in 2008, but provided significantly greater protection than chemigation in 2009.

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