A ROOT AND STALK ROT OF SOYBEANS CAUSED BY PHYTOPHTHORA MEGASPERMA DRECHSLER VAR. SOJAE VAR. NOV.

1959 ◽  
Vol 37 (5) ◽  
pp. 927-957 ◽  
Author(s):  
A. A. Hildebrand
Keyword(s):  
Root Rot ◽  
The United States ◽  
Sweet Clover ◽  
Phytophthora Megasperma ◽  
Breeding Lines ◽  
Disease Reaction ◽  
Stalk Rot ◽  
Causal Fungus ◽  
Glycine Max L ◽  
Marked Specificity

Since 1954, a destructive root and stalk rot of soybeans, identical with one reported from several of the soybean-growing areas in the United States, has been prevalent in southwestern Ontario. It is proposed that Phytophthora megasperma Drechsler var. sojae nov. var. replace P. cactorum (Lib. and Cohn) Schroet., and P. sojae Kaufmann and Gerdemann, as the more correct taxonomic designation of the causal fungus. P. megasperma var. sojae comprises strains which though indistinguishable morphologically, differ physiologically and pathologically. Artificial inoculation of varieties and of breeding lines and selections of soybeans with the causal fungus, chiefly by the highly reliable toothpick method, indicated two well-defined types of disease reaction, resistance and susceptibility. Harosoy, the variety which currently is grown most extensively in Ontario, is highly susceptible to the disease. Pathogenicity trials involving many possible wild and cultivated hosts emphasized the marked specificity of P. megasperma var. sojae to Glycine max L. Merrill. The soybean Phytophthora, having been called P. cactorum and thereby associated nomenclaturally with a representative of that species causing a root rot of sweet clover in Ontario, was found to be quite different from the sweet clover pathogen.

scholarly journals First Report of Phytophthora megasperma and Pythium irregulare As Olive Tree Root Pathogens

Plant Disease ◽  
1997 ◽  
Vol 81 (10) ◽  
pp. 1216-1216 ◽  
Author(s):  
M. E. Sánchez-Hernández ◽  
A. Ruiz-Dávila ◽  
A. Trapero-Casas
Keyword(s):  
Root Rot ◽  
Olive Tree ◽  
The United States ◽  
Damping Off ◽  
Phytophthora Megasperma ◽  
Root Rots ◽  
Foliar Symptoms ◽  
Root Pathogens ◽  
Root Necrosis ◽  
Olive Trees

Several species of the genus Phytophthora are associated with root rot and trunk cankers in olive trees (Olea europaea L.). Among them, Phytophthora megasperma has been cited as being associated with olive root rots in Greece (1). Unidentified species of Pythium and Phytophthora have also been associated with olive tree root rots in the United States. However, the status of P. megasperma and Pythium spp. as olive tree root pathogens has remained unclear. Following a 5-year period of severe drought in southern Spain, autumn-winter rainfall rates in 1996 to 1997 steadily increased in both quantity and frequency. Under these unusually wet conditions, olive trees remained waterlogged for several months. During this period, we observed foliar wilting, dieback, and death of young trees, and later found extensive root necrosis. In 46 of 49 affected plantations surveyed, P. megasperma was consistently isolated from the rotted rootlets, particularly in young (<1- to 10-year-old trees) plantations. This fungus was not detected on plant material affected by damping-off from several Spanish olive tree nurseries. The opposite situation occurred with P. irregulare. This species was not associated with rotted rootlets in the field. In contrast, it was consistently isolated from necrotic rootlets from young olive plants affected by damping-off. These plants were grown in a sand-lime-peat soil mixture under greenhouse conditions and showed foliar wilting and extensive necrosis of the root systems. Pathogenicity tests were conducted with several isolates of P. megasperma and P. irregulare on 6-month-old rooted cuttings of olive, under both weekly watering and waterlogged conditions. Under waterlogged conditions, both fungal species produced extensive root necrosis 2 weeks after inoculation that resulted in wilting of the aerial parts and rapid plant death. Waterlogged control plants remained without foliar symptoms but a low degree of root necrosis was recorded. In addition, under weekly watering conditions, plants inoculated with either species showed some degree of root rot but foliar symptoms were not evident. No differences in pathogenicity were observed within the Phytophthora or Pythium isolates. Reference: (1) H. Kouyeas and A. Chitzanidis. Ann. Inst. Phytopathol. Benaki 8:175, 1968.

RCAT Persian soybean

1991 ◽  
Vol 71 (1) ◽  
pp. 175-176
Author(s):  
G. R. Ablett ◽  
W. D. Beversdorf
Keyword(s):  
Glycine Max ◽  
Root Rot ◽  
Yield Potential ◽  
Maturity Group ◽  
Phytophthora Megasperma ◽  
Phytophthora Root Rot ◽  
Group I ◽  
Glycine Max L ◽  
Cultivar Description ◽  
Late Maturity

RCAT Persian is a mid-late Maturity Group I soybean [Glycine max L. (Merr.)] cultivar with excellent yield potential, good lodging tolerance and resistance to most races of phytophthora root rot caused by Phytophthora megasperma f. sp. glycinea (Pmg) found in Ontario. Key words: Soybean, cultivar description

CHEMICAL AND BIOLOGICAL CONTROL OF PHYTOPHTHORA ROOT AND STALK ROT OF SOYBEAN

1979 ◽  
Vol 59 (2) ◽  
pp. 307-311 ◽  
Author(s):  
O. VAARTAJA ◽  
R. I. BUZZELL ◽  
L. G. CRAWFORD ◽  
R. E. PITBLADO
Keyword(s):  
Biological Control ◽  
Field Tests ◽  
Short Term ◽  
Phytophthora Megasperma ◽  
Plant Survival ◽  
Stalk Rot ◽  
Low Degree ◽  
Gliocladium Virens ◽  
Glycine Max L ◽  
Fungal Antagonist

Chemical and biological control of root and stalk rot of soybean (Glycine max (L.) Merr.) caused by Phytophthora megasperma Drechs. var. sojae Hildebr. (Pms) was attempted in greenhouse and field tests. In-furrow spray-drench and granular treatments of the experimental compound CGA 48988 (Ciba-Geigy), applied at planting time at rates ranging from 0.5 to 2.0 kg a.i./ha, greatly reduced loss of plants from the disease and doubled the yield of the cultivar Steele, which has a low degree of field tolerance to Pms race 6. An in-furrow spray-drench treatment with thiram at 1.0 kg a.i./ha significantly reduced loss of plants, but not as much as CGA 48988 and not sufficiently to increase yield. Captan and CGA 48988 applied to Harosoy 63 seeds (at 0.13 and 0.33 g a.i./kg of seed, respectively) by a pelleting technique gave short-term control in the greenhouse, but did not significantly increase plant survival and yield in the field. CGA 48988, which is systemic in soybeans, increased plant survival and. yield in the field at 1.65 g a.i./kg of seed in seed pellets. Inclusion of the fungal antagonist Gliocladium virens Miller, Giddens and Foster in seed pellets did not significantly control Pms either alone or in combination with a low rate of captan or CGA 48988.

RCAT Angora soybean

1993 ◽  
Vol 73 (1) ◽  
pp. 179-180
Author(s):  
G. R. Ablett ◽  
J. W. Tanner
Keyword(s):  
Glycine Max ◽  
Key Words ◽  
Root Rot ◽  
Yield Potential ◽  
Maturity Group ◽  
Phytophthora Megasperma ◽  
Phytophthora Root Rot ◽  
Glycine Max L ◽  
Cultivar Description ◽  
Late Maturity

RCAT Angora is a mid-late Maturity Group II soybean (Glycine max (L.) Merr.) cultivar with excellent yield potential and resistance to most races of phytophthora root rot caused by Phytophthora megasperma f. sp. glycinea (RMG) found in Ontario. Key words: Soybean, cultivar description

Races of Phytophthora sojae on Soybean in Illinois

2000 ◽  
Vol 1 (1) ◽  
pp. 32
Author(s):  
R. A. Leitz ◽  
G. L. Hartman ◽  
W. L. Pedersen ◽  
C. D. Nickell
Keyword(s):  
United States ◽  
Glycine Max ◽  
Root Rot ◽  
The United States ◽  
Phytophthora Sojae ◽  
Phytophthora Root Rot ◽  
Glycine Max L

Phytophthora root rot of soybean (Glycine max (L.) Merr.), caused by Phytophthora sojae M. J. Kauffmann & J. W. Gerdemann, has been isolated throughout the soybean-producing regions of the United States. Posted 3 June 2000.

RCAT Columbus soybean

1996 ◽  
Vol 76 (1) ◽  
pp. 135-136
Author(s):  
G. R. Ablett ◽  
B.T. Stirling ◽  
J. D. Fischer
Keyword(s):  
Root Rot ◽  
Yield Potential ◽  
Maturity Group ◽  
Lodging Resistance ◽  
Phytophthora Megasperma ◽  
Phytophthora Root Rot ◽  
Good Tolerance ◽  
Glycine Max L ◽  
Cultivar Description ◽  
Late Maturity

RCAT Columbus is a late Maturity Group II soybean [Glycine max (L.) Merr.] cultivar with excellent yield potential and lodging resistance and with good tolerance to phytophthora root rot caused by Phytophthora megasperma f. sp. glycinea. Key words: Soybean, cultivar description

RCAT Tabby soybean

1993 ◽  
Vol 73 (4) ◽  
pp. 1103-1104
Author(s):  
G. R. Ablett ◽  
J. W. Tanner
Keyword(s):  
Glycine Max ◽  
Key Words ◽  
Root Rot ◽  
Yield Potential ◽  
Maturity Group ◽  
Lodging Resistance ◽  
Phytophthora Megasperma ◽  
Phytophthora Root Rot ◽  
Glycine Max L ◽  
Cultivar Description

RCAT Tabby is a mid Maturity Group II soybean [Glycine max (L.) Merr.] cultivar with excellent yield potential, lodging resistance and with resistance to most races of phytophthora root rot caused by Phytophthora megasperma f. sp. glycinea (PMG) found in Ontario. Key words: Soybean, cultivar description

scholarly journals Races of Phytophthora sojae on Soybean in Illinois

Plant Disease ◽  
2000 ◽  
Vol 84 (4) ◽  
pp. 487-487 ◽  
Author(s):  
R. A. Leitz ◽  
G. L. Hartman ◽  
W. L. Pedersen ◽  
C. D. Nickell
Keyword(s):  
Root Rot ◽  
Genetic Resistance ◽  
The United States ◽  
Phytophthora Sojae ◽  
Diseased Plant ◽  
American Phytopathological Society ◽  
Phytophthora Root Rot ◽  
Glycine Max L ◽  
New Race ◽  
Soybean Diseases

Phytophthora root rot of soybean (Glycine max (L.) Merr.), caused by Phytophthora sojae M. J. Kauffmann & J. W. Gerdemann, has been isolated throughout the soybean-producing regions of the United States. There are more than 39 identified races of P. sojae pathogenic on soybean, and 13 host resistance alleles have been identified at 7 loci (1). None of these alleles confers resistance to all races of P. sojae. The most commonly used resistance allele, Rps1k, confers resistance to the greatest number of races (2). The objective of this study was to identify races of P. sojae in Illinois soybean fields to determine whether the currently used resistance alleles are effective against the P. sojae races found in Illinois. Soybean breeders must be aware of the existence and distribution of races to incorporate appropriate sources of genetic resistance into cultivars. From 192 soil samples collected throughout Illinois in 1997, 33 isolates were obtained and identified to race by inoculating Rps isolines of soybean cv. Williams. A new race with virulence to the Rps1d and Rps7 alleles, designated as race 54, accounted for 48% of the isolates. Another new race with virulence to Rps1d, Rps3a, Rps3c, Rps4, Rps5, Rps6, and Rps7 alleles, designated race 55, was identified in one sample. One isolate, identified as race 41, was obtained from a diseased plant with the Rps1k allele. Another isolate, identified as race 43, was obtained from a diseased plant with the Rps1c allele. Based on virulence patterns of P. sojae, most of the isolates obtained from Illinois soils were races 1, 3, and 4 or variants of these races, such as race 54, with added virulence to the Rps1d allele. References: (1) A. F. Schmitthenner. 1999. Compendium of Soybean Diseases. 4th ed. G. L. Hartman, J. B. Sinclair, and J. C. Rupe, eds. The American Phytopathological Society, St. Paul, MN. pp. 39‐42. (2) A. F. Schmitthenner, M. Hobe, and R. G. Bhat. Plant Dis. 78:269, 1994

Brock soybean

1993 ◽  
Vol 73 (1) ◽  
pp. 175-176 ◽  
Author(s):  
G. R. Ablett ◽  
J. W. Tanner
Keyword(s):  
Glycine Max ◽  
Key Words ◽  
Root Rot ◽  
Yield Potential ◽  
Maturity Group ◽  
Phytophthora Megasperma ◽  
Phytophthora Root Rot ◽  
Group I ◽  
Glycine Max L ◽  
Cultivar Description

Brock is a mid-Maturity Group I soybean (Glycine max (L.) Merr.) cultivar with excellent yield potential and lodging tolerance and with resistance to most races of phytophthora root rot caused by Phytophthora megasperma f. sp. glycinea (PMG) found in Ontario. Key words: Soybean, cultivar description

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.

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