Resistance to phytophthora erythroseptica and pythium ultimum in a potato clone derived from s. berthaultii and s. etuberosum

2007 ◽  
Vol 84 (2) ◽  
pp. 149-160 ◽  
Author(s):  
Asunta L. Thompson ◽  
Raymond J. Taylor ◽  
Julie S. Pasche ◽  
Richard G. Novy ◽  
Neil C. Gudmestad
Keyword(s):  
Pythium Ultimum ◽  
Potato Clone ◽  
Phytophthora 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.

Inhibition of Fungal Growth by Macerated Plant Tissues in a Closed Environment

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 476e-476
Author(s):  
Craig S. Charron ◽  
Catherine O. Chardonnet ◽  
Carl E. Sams
Keyword(s):  
Radial Growth ◽  
Fungal Pathogens ◽  
Solid Phase ◽  
Indian Mustard ◽  
Fungal Growth ◽  
Allyl Isothiocyanate ◽  
Pythium Ultimum ◽  
Alternative Methods ◽  
Gas Chromatography Mass Spectrometry ◽  
Clean Air

The U.S. Clean Air Act bans the use of methyl bromide after 2001. Consequently, the development of alternative methods for control of soilborne pathogens is imperative. One alternative is to exploit the pesticidal properties of macerated tissues of Brassica spp. This study tested the potential of several Brassica spp. for control of fungal pathogens. Pythium ultimum Trow or Rhizoctonia solani Kühn plugs on potato-dextrose agar on petri dishes were sealed in 500-ml glass jars (at 22 °C) containing macerated leaves (10 g) from one of six Brassica spp. Radial growth was measured 24, 48, and 72 h after inoculation. Indian mustard (B. juncea) was the most suppressive, followed by `Florida Broadleaf' mustard (B. juncea). Volatile compounds in the jars were sampled with a solid-phase microextraction device (SPME) and identified by gas chromatography-mass spectrometry (GC-MS). Allyl isothiocyanate (AITC) comprised over 90% of the total volatiles measured from Indian mustard and `Florida Broadleaf' mustard. Isothiocyanates were detected in jars with all plants except broccoli. (Z)-3-hexenyl acetate was emitted by all plants and was the predominant volatile of `Premium Crop' broccoli (B. oleracea L. var. italica), `Michihili Jade Pagoda' Chinese cabbage (B. pekinensis), `Charmant' cabbage (B. oleracea L. var. capitata), and `Blue Scotch Curled' kale (B. oleracea L. var. viridis). To assess the influence of AITC on radial growth of P. ultimum and R. solani, AITC was added to jars to give headspace concentrations of 0.10, 0.20, and 0.30 mg·L–1 (mass of AITC per volume of headspace). Growth of both fungi was inhibited by 0.10 mg·L–1 AITC. 0.20 mg·L–1 AITC was fungicidal to P. ultimum although the highest AITC level tested (0.30 mg·L–1) did not terminate R. solani growth. These results indicate that residues from some Brassica spp. may be a viable part of a soilborne pest control strategy.

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