Effects of inoculum source and irrigation on black dot disease of potatoes (Colletotrichum coccodes (Wallr.) Hughes) and its development during storage

1988 ◽  
Vol 31 (3) ◽  
pp. 493-500 ◽  
Author(s):  
P. J. Read ◽  
G. A. Hide
Keyword(s):  
Colletotrichum Coccodes ◽  
Black Dot ◽  
Inoculum Source

scholarly journals Effect of light duration on severity of black dot caused by Colletotrichum coccodes on potato

2004 ◽  
Vol 53 (3) ◽  
pp. 288-293 ◽  
Author(s):  
L. Tsror (Lahkim)
Keyword(s):  
Colletotrichum Coccodes ◽  
Black Dot ◽  
Light Duration ◽  
Effect Of Light

scholarly journals Occurrence of Black Dot of Potato Caused by Colletotrichum coccodes in Central Italy

Plant Disease ◽  
2002 ◽  
Vol 86 (5) ◽  
pp. 562-562 ◽  
Author(s):  
R. Buonaurio ◽  
G. Natalini ◽  
L. Covarelli ◽  
C. Cappelli
Keyword(s):  
Solanum Tuberosum L ◽  
Disease Incidence ◽  
Central Italy ◽  
Morphological Characteristics ◽  
Fungal Growth ◽  
Soil Surface ◽  
The United States ◽  
Colletotrichum Coccodes ◽  
Tuber Quality ◽  
Black Dot

Between 1997 and 2000, black dot of potato (Solanum tuberosum L.), caused by the polyphagous soilborne fungus Colletotrichum coccodes (Wallr.) Hughes, was observed each summer in fields located in Umbria (central Italy). Disease incidence ranged from 50 to 100%, and early potato cultivars were generally more susceptible than late-maturing ones. Disease symptoms were first observed during August as a yellowing and wilting of foliage in the tops of plants, followed by rotting of the roots and stems, which led to the premature death of 50 to 70% of plants. Setose1 sclerotia (300 to 500 mm in diameter) and acervuli of the fungus were found on roots and stems of infected plants. Acervuli produced hyaline, aseptate, cylindrical conidia (16 to 22 × 2.5 to 4.5 μm) formed on unicellular cylindrical phialidic conidiophores. The fungus was isolated from diseased stems and roots on potato dextrose agar (PDA) at pH 6.5. Pathogenicity of the fungus was confirmed by fulfilling Koch's postulates using 3- to 4-week-old potato plants of a local cultivar. A superficial 5-mm vertical cut was made with a scalpel into the base of potato stems (2 cm beneath the soil surface), and 5-mm-diameter plugs of PDA alone (control plants) or PDA plus fungal growth were placed over the cuts. The wounds were sealed with wet cotton swabs that were held in place with Parafilm. Symptoms that resembled those in the field were observed on inoculated plants 6 to 8 weeks postinoculation. Symptoms did not appear on the control plants. The same fungus was reisolated from the diseased plants. Based on morphological characteristics of sclerotia, acervuli, and conidia, as well as pathogenicity tests, the fungus was identified as C. coccodes. To our knowledge, this is the first report of C. coccodes as the causal agent of black dot of potato in central Italy. We did not observe foliar outbreaks of the disease, which were reported from the United States (2). In both 1921 (1) and 1951 (3), the fungus was reported to cause severe outbreaks of the disease in northern Italy. Since then, its presence in Italy has been rarely recorded in potato (4). The occurrence of extremely dry and hot weather conditions during the summers of 1997 to 2000, which are favorable for disease development, made the disease particularly severe. We cannot exclude the possibility that the disease may have been present in central Italy before our observations, as it can be misdiagnosed and its symptoms can be masked by the symptoms of other diseases. The significance of black dot in central Italy needs to be reappraised in terms of both yield loss and tuber quality. References: (1) C. Arnaudi. Atti Ist. Bot. Univ. Pavia. Ser. 3, 1:71, 1924. (2) A. W. Barkdoll and J. R. Davis. Plant Dis. 76:131, 1992. (3) G. Goidanich. Inf. Fitopatol. 1:5, 1951. (4) S. Vitale et al. J. Plant Pathol. 80:265, 1998.

scholarly journals Black dot (Colletotrichum coccodes): an increasingly important disease of potato

2003 ◽  
Vol 52 (1) ◽  
pp. 3-12 ◽  
Author(s):  
A. K. Lees ◽  
A. J. Hilton
Keyword(s):  
Colletotrichum Coccodes ◽  
Black Dot ◽  
Important Disease

scholarly journals Field Resistance to Potato Stem Colonization by the Black Dot Pathogen Colletotrichum coccodes

Plant Disease ◽  
2009 ◽  
Vol 93 (11) ◽  
pp. 1116-1122 ◽  
Author(s):  
Nadav Nitzan ◽  
Marc A. Evans ◽  
Tom F. Cummings ◽  
Dennis A. Johnson ◽  
Dallas L. Batchelor ◽  
...  
Keyword(s):  
Disease Severity ◽  
Genetic Stability ◽  
Field Trials ◽  
Field Resistance ◽  
Powdery Scab ◽  
Colletotrichum Coccodes ◽  
Environment Interaction ◽  
Solanum Bulbocastanum ◽  
Black Dot ◽  
Root Knot Nematode

Potato (Solanum tuberosum) germplasm was tested for resistance to stem colonization by the black dot pathogen Colletotrichum coccodes. Forty-six potato selections were tested in three field trials from 2006 to 2008. Resistance was determined by comparing disease severity on aboveground stems to the mean disease severity of the industry standards Russet Burbank, Ranger Russet, and Umatilla Russet. The potato selections were also tested for genotype*environment interaction to determine their genetic stability. Heritability of resistance was calculated to be 0.13 with confidence intervals between 0.00 and 0.68. The selections A0012-5, PA95B2-4, PA98NM38-1, and PO94A009-7 had less black dot than the standards in all years, and also demonstrated genetic stability. These selections also possess resistance to the root galling stage of the powdery scab pathogen Spongospora subterranea f. sp. subterranea. PA95B2-4, PA98NM38-1, and PO94009-7 were derived from an introgression program to incorporate resistance to the Columbia root-knot nematode Meloidogyne chitwoodi from the Mexican wild species Solanum bulbocastanum, and also have the commercial cultivar Summit Russet in their ancestry. These selections are promising steps toward sustainable management of black dot and powdery scab and will be further tested and used for breeding purposes.

scholarly journals First Report of Black Dot Root Rot, Caused by Colletotrichum coccodes, on Tomato in Kentucky High Tunnels

Plant Disease ◽  
2019 ◽  
Vol 103 (8) ◽  
pp. 2126
Author(s):  
E. Fealko ◽  
D. Szarka ◽  
A. Lamb ◽  
B. Amsden ◽  
J. Beale ◽  
...  
Keyword(s):  
Root Rot ◽  
Colletotrichum Coccodes ◽  
Black Dot ◽  
First Report ◽  
High Tunnels

scholarly journals Effect of Seed-Tuber Generation, Soilborne Inoculum, and Azoxystrobin Application on Development of Potato Black Dot Caused by Colletotrichum coccodes

Plant Disease ◽  
2005 ◽  
Vol 89 (11) ◽  
pp. 1181-1185 ◽  
Author(s):  
N. Nitzan ◽  
T. F. Cummings ◽  
D. A. Johnson
Keyword(s):  
Disease Severity ◽  
Seed Tuber ◽  
Russet Burbank ◽  
Yield Reduction ◽  
Colletotrichum Coccodes ◽  
Potato Seed ◽  
Disease Development ◽  
Black Dot ◽  
Potato Black Dot

The effect of azoxystrobin on potato black dot and the role of seed- and soilborne inocula of Colletotrichum coccodes in the development of black dot were evaluated in the field using two potato seed generations (generation 1 and 3) of the susceptible cvs. Norkotah Russet and Russet Burbank over 3 years (2002 to 2004). Plants of Norkotah Russet and Russet Burbank treated with azoxystrobin had 13 and 23% higher yields, respectively, than nontreated plants in 2003. Disease severity on both cultivars was reduced 19 to 81%, and 22 to 81% on above- and belowground stem sections, respectively, when plants were treated with azoxystrobin. Plants of both cultivars that were treated with azoxystrobin had 9 to 26% less infected progeny tubers than the nontreated plants. These results indicated the efficacy of azoxystrobin to reduce black dot severity on both stems and progeny tubers. The roles of seed- and soilborne inocula in disease development were evaluated in 2003 and 2004 using generation 1 and 3 seed tubers. The incidence of C. coccodes in generation 1 mother tubers of Norkotah Russet and Russet Burbank were 2 and 16% in 2003, respectively, and 0 and 30% in 2004, respectively. The incidence of C. coccodes in generation 3 mother tubers of Norkotah Russet and Russet Burbank were 14 and 49% in 2003, respectively, and 12 and 38% in 2004, respectively. Generation 1 plants of Norkotah Russet had 36 and 13% greater yield than generation 3 plants in 2003 and 2004, respectively. In 2004, generation 1 plants of Norkotah Russet and Russet Burbank had 26 and 15% greater disease severity, respectively, on belowground stem than generation 3 plants. Generation 1 plants of Norkotah Russet had 7.5 and 11% more infected progeny tubers in 2003 and 2004, respectively, than generation 3. Significant differences for yield reduction and incidence of infected progeny tubers between the two seed generations were not recorded for Russet Burbank, suggesting that the effect of inoculum source of C. coccodes on black dot severity may be cultivar specific.

scholarly journals Vegetative Compatibility Groups in Colletotrichum coccodes, the Causal Agent of Black Dot on Potato

2002 ◽  
Vol 92 (8) ◽  
pp. 827-832 ◽  
Author(s):  
N. Nitzan ◽  
M. Hazanovsky ◽  
M. Tal ◽  
L. Tsror(Lahkim)
Keyword(s):  
Genetic Diversity ◽  
The Netherlands ◽  
Economic Importance ◽  
Vegetative Compatibility ◽  
Colletotrichum Coccodes ◽  
Black Dot ◽  
Vegetative Compatibility Groups ◽  
Nit Mutants ◽  
Pathogenicity Tests ◽  
Self Compatibility

Black dot of potato, caused by Colletotrichum coccodes, is a disease of growing economic importance, but the degree of genetic diversity and pathogenic differentiation among isolates is unknown. Using nitrate auxotrophic (Nit) mutants, we characterized vegetative compatibility groups (VCG) diversity for C. coccodes for 110 isolates originating from Israel, The Netherlands, and France. We recovered frequencies of nit1 and NitM mutant classes at 38.5 and 7.2%, respectively, and selected 12 isolates as tester isolates. Using these testers, we defined four multimember VCGs at 7.3, 35.5, 20.0, and 10.0% frequency in this sample. Thirty isolates (27.3% of all tested isolates) could not be assigned to any of the major groups, and showed only self-compatibility. The frequency of recovery of Nit mutant sectors was highest in isolates from VCG4, with 50.9 and 13.6% recovery for nit1 and NitM, respectively. However, we did not detect differences in the frequency of mutant classes among the three countries of origin. In pathogenicity tests, isolates from VCG3 were the most aggressive to potato, as expressed by high stem colonization levels and sclerotia density on root and crown. These results suggest that there is significant VCG diversity in this species and that this VCG diversity may be correlated with pathogenic characteristics or specialization.

Colonization of roots, stolons, tubers and stems of various potato ( Solanum tuberosum ) cultivars by the black‐dot fungus Colletotrichum coccodes

1998 ◽  
Vol 47 (4) ◽  
pp. 440-445 ◽  
Author(s):  
D. Andrivon ◽  
J.‐M. Lucas ◽  
C. Guérin ◽  
B. Jouan
Keyword(s):  
Solanum Tuberosum ◽  
Colletotrichum Coccodes ◽  
Black Dot
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