Association between genotypes of the brown stem rot pathogenPhialophora gregataand resistant and susceptible soybean cultivars in the north-central United States and Ontario

2008 ◽  
Vol 30 (4) ◽  
pp. 581-587 ◽  
Author(s):  
D.K. Malvick ◽  
E. Grunden
Keyword(s):  
United States ◽  
Stem Rot ◽  
North Central ◽  
Brown Stem Rot ◽  
Soybean Cultivars ◽  
The North ◽  
Central United States

scholarly journals Characterization and Distribution of Two Races of Phialophora gregata in the North-Central United States

2003 ◽  
Vol 93 (7) ◽  
pp. 901-912 ◽  
Author(s):  
T. C. Harrington ◽  
J. Steimel ◽  
F. Workneh ◽  
X. B. Yang
Keyword(s):  
Genetic Variation ◽  
Stem Rot ◽  
North Central ◽  
Brown Stem Rot ◽  
Phialophora Gregata ◽  
The North ◽  
Foliar Symptoms ◽  
Central United States ◽  
Soybean Plants ◽  
Xylem Discoloration

Genetic variation and variation in aggressiveness in Phialophora gregata f. sp. sojae, the cause of brown stem rot of soybean, was characterized in a sample of 209 isolates from the north-central region. The isolates were collected from soybean plants without regard to symptoms from randomly selected soybean fields. Seven genotypes (A1, A2, A4, A5, A6, M1, and M2) were distinguished based on DNA fingerprinting with microsatellite probes (CAT)5 and (CAC)5, with only minor genetic variation within the A or M genotypes. Only the A1, A2, and M1 genotypes were represented by more than one isolate. The A genotypes dominated in the eastern Iowa, Illinois, and Ohio samples, whereas the M genotypes were dominant in samples from western Iowa, Minnesota, and Missouri. In growth chamber experiments, isolates segregated into two pathogenicity groups based on their aggressiveness toward soybean cvs. Kenwood and BSR101, which are relatively susceptible and resistant, respectively, to brown stem rot. In both root dip inoculation and inoculation by injecting spores into the stem near the ground line (stab inoculations), isolates of the A genotypes caused greater foliar symptoms and more vascular discoloration than isolates of the M genotypes on both cultivars of soybean. All isolates caused foliar symptoms in both cultivars and in three additional cultivars of soybean with resistance to brown stem rot. Greater differences between the A and M genotypes were seen in foliar symptoms than in the linear extent of xylem discoloration, and greater differences were seen in Kenwood than in BSR101. Inoculation of these genotypes into five cultivars of soybean with different resistance genes to brown stem rot showed a genotype × cultivar interaction. A similar distinction was found in an earlier study of the adzuki bean pathogen, P. gregata f. sp. adzukicola, and consistent with the nomenclature of that pathogen, the soybean pathogens are named the aggressive race (race A) and the mild race (race M) of P. gregata f. sp. sojae.

scholarly journals Prevalence of Sclerotinia Stem Rot of Soybeans in the North-Central United States in Relation to Tillage, Climate, and Latitudinal Positions

2000 ◽  
Vol 90 (12) ◽  
pp. 1375-1382 ◽  
Author(s):  
F. Workneh ◽  
X. B. Yang
Keyword(s):  
United States ◽  
Stem Rot ◽  
Sclerotinia Stem Rot ◽  
North Central ◽  
The North ◽  
No Till ◽  
Central United States ◽  
Zigzag Pattern ◽  
Tillage System ◽  
Investigation Period

Since the early 1990s, Sclerotinia stem rot, caused by Sclerotinia sclerotiorum, has caused considerable damage to soybean production in the north-central United States. To determine the extent of its distribution and associated factors, investigations were conducted in 1995 and 1996 in Illinois, Iowa, Minnesota, Missouri, and Ohio. Investigations also were conducted in 1997 and 1998 in Iowa, Minnesota, and Missouri. In each state, soybean fields were randomly selected in collaboration with the National Agricultural Statistics Service. From each field, 20 soybean stems 20 cm long (from the base) in 1995 and 1996 and full-length stems in 1997 and 1998 were sampled in a zigzag pattern. During the 4-year period, stem samples were collected from 1,983 fields and assessed for the presence or absence of the disease. Of the five states, Sclerotinia stem rot was most prevalent in north-central Iowa and southern Minnesota. Sclerotinia stem rot was not detected in Missouri during the 4-year investigation period. The disease was most prevalent in 1996 and least prevalent in 1995. The prevalence of the disease was strongly related to cumulative departures from normal maximum and minimum temperatures in July and August. The disease was more prevalent when yearly temperatures were below normal than when they were above normal. In 1996, a year with a cooler-than-normal summer, the disease was detected farther south than in 1995. In both years, the prevalence of the disease was exponentially related to latitudinal positions of the fields (R2 = 0.93 and 0.83 for 1995 and 1996, respectively) reflecting the effect of the north-south variations in temperature. During the 4-year period, there was no relationship between precipitation and the prevalence of the disease. The lack of relationship may suggest that there was no shortage of moisture since it is one of the primary factors for disease development. The prevalence of Sclerotinia stem rot was less in no-till than in minimum-till or conventional-till fields (P = 0.001 and 0.007, respectively) and greater in minimum-till than in conventional-till fields (P = 0.07). Fields that had Sclerotinia stem rot, however, did not differ in incidence of the disease regardless of the tillage system.

scholarly journals Genetic Variation of Sclerotinia sclerotiorum from Multiple Crops in the North Central United States

PLoS ONE ◽  
2015 ◽  
Vol 10 (9) ◽  
pp. e0139188 ◽  
Author(s):  
Laura Aldrich-Wolfe ◽  
Steven Travers ◽  
Berlin D. Nelson
Keyword(s):  
United States ◽  
Genetic Variation ◽  
Sclerotinia Sclerotiorum ◽  
North Central ◽  
The North ◽  
Central United States

Relation of algal biovolume to chlorophyll a in selected lakes and wetlands in the north-central United States

1995 ◽  
Vol 52 (2) ◽  
pp. 416-424 ◽  
Author(s):  
James W. LaBaugh
Keyword(s):  
United States ◽  
North Dakota ◽  
Chlorophyll A ◽  
Linear Relation ◽  
Algal Biomass ◽  
Open Water ◽  
Light Penetration ◽  
North Central ◽  
The North ◽  
Central United States

Algal chlorophyll a is commonly used as a surrogate for algal biomass. Data from three lakes in western Nebraska, five wetlands in north-central North Dakota, and two lakes in north-central Minnesota represented a range in algal biovolume of over four orders of magnitude and a range in chlorophyll a from less than 1 to 380 mg∙m−3. Analysis of these data revealed that there was a linear relation, log10 algal biovolume = 5.99 + 0.09 chlorophyll a (r2 = 0.72), for cases in which median values of chlorophyll a for open-water periods were less than 20 mg∙m−3. There was no linear relation in cases in which median chlorophyll a concentrations were larger than 20 mg∙m−3 for open-water periods, an occurrence found only in shallow prairies lakes and wetlands for years in which light penetration was the least.

Processing Snap Bean Variety Responses to Applied Nitrogen and Irrigation in the North Central United States

2015 ◽  
Vol 107 (4) ◽  
pp. 1401-1410 ◽  
Author(s):  
Yi Wang ◽  
Matthew D. Ruark ◽  
Amanda J. Gevens ◽  
Don T. Caine ◽  
Amanda L. Raster ◽  
...  
Keyword(s):  
United States ◽  
Snap Bean ◽  
North Central ◽  
The North ◽  
Bean Variety ◽  
Central United States ◽  
Applied Nitrogen
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