Initiation and development of cankers caused by virulent and cytoplasmic hypovirulent isolates of the chestnut blight fungus

1984 ◽  
Vol 62 (12) ◽  
pp. 2660-2664 ◽  
Author(s):  
J. S. Russin ◽  
L. Shain
Keyword(s):  
Moisture Content ◽  
Electrical Resistance ◽  
American Chestnut ◽  
Chestnut Blight ◽  
Moisture Contents ◽  
Chestnut Blight Fungus ◽  
Cork Borer ◽  
Endothia Parasitica ◽  
Canker Development

Stems of American chestnut were inoculated with a virulent (V) isolate of Endothia parasitica alone or containing different agents for cytoplasmic hypovirulence (CH). The V isolate (EP 155) initiated cankers in cork borer wounds 0,1,2,4,7,14,21, or 28 days old. Infection of this V isolate with CH agents Hl2 (EP 780), HMU (EP 868) or HT2 (EP 905), restricted canker development to wounds 0–7 days old, Odays old, or to none of the wounds 0–28 days old, respectively. Inoculation of several wound types with V or CH conidia collected from cankers or agar cultures resulted in few cankers. Measurement of electrical resistance (ER) of bark at different heights along chestnut stems indicated that ER was lowest at stem bases. Cankers initiated artificially at stem bases with mycelium from V or CH isolates were smaller and enlarged more slowly than did cankers initiated at more elevated stem positions. Areas of cankers initiated in detached chestnut stems in which moisture contents were regulated were inversely related to moisture content and directly related to ER of chestnut bark.

Birds and mammals as vectors of the chestnut blight fungus (Endothia parasitica)

1981 ◽  
Vol 59 (9) ◽  
pp. 1647-1650 ◽  
Author(s):  
Craig S. Scharf ◽  
Nancy K. DePalma
Keyword(s):  
Hardwood Forests ◽  
American Chestnut ◽  
Forest Community ◽  
Chestnut Blight ◽  
Chestnut Blight Fungus ◽  
Endothia Parasitica

This study investigated the potential of birds and mammals to vector the chestnut blight fungus in today's mixed hardwood forests. Animals were shot or trapped in established woodland plots in southern Connecticut where densities of American chestnut sprouts were high, brought back to the laboratory, and examined for the presence of Endothia parasitica. Results showed that birds and mammals can transport virulent and hypovirulent-like strains of E. parasitica in today's forest community. Two birds, a mouse, and a shrew were identified as carriers of the blight fungus; the shrew harbored a hypovirulent-like strain introduced onto the plot 2 years earlier.

scholarly journals Detection of natural infection of Quercus spp. by the chestnut blight fungus (Cryphonectria parasitica) in Hungary

2002 ◽  
Vol 8 (2) ◽  
Author(s):  
L. Radócz ◽  
I. J. Holb
Keyword(s):  
Natural Infection ◽  
Cryphonectria Parasitica ◽  
Castanea Dentata ◽  
American Chestnut ◽  
Chestnut Blight ◽  
Chestnut Blight Fungus ◽  
European Chestnut ◽  
Total Destruction ◽  
Quercus Spp ◽  
Endothia Parasitica

The chestnut blight fungus Cryphonectria parasitica (Murrill) Barr [syn.: Endothia parasitica (Murr) Anderson] caused almost total destruction of the American chestnut (Castanea dentata) and widely spread on European chestnut (Castanea saliva) in many European countries. In Hungary, because this fungus threatens most of the Hungarian chestnut stands, great efforts have been made to delay its spread. Biological control with Hungarian hypovirulent strains of the pathogen seems to be an effective method for saving the affected chestnut trees. Until 1998 the fungus was detected on Castanea saliva only, then on some trees of young Quercus petrea in mixed chestnut forests, which also showed the typical symptoms of blight (Kőszeg and Zengővárkony). Although blight symptoms are not so serious in Quercus spp. than in Castanea spp., it seems that C. parasitica threatens the young Quercus spp. in Hungary, mainly in heavily infected chestnut forests. This is the first report of C. parasitica cankers on oak in Hungary.

Population biology of the chestnut blight fungus, Cryphonectria parasitica

1995 ◽  
Vol 73 (S1) ◽  
pp. 311-319 ◽  
Author(s):  
Michael G. Milgroom
Keyword(s):  
Gene Flow ◽  
North America ◽  
Population Biology ◽  
Random Mating ◽  
Cryphonectria Parasitica ◽  
Vegetative Compatibility ◽  
Chestnut Blight ◽  
Vegetative Compatibility Groups ◽  
Chestnut Blight Fungus ◽  
Endothia Parasitica

Interest in the population biology of the chestnut blight fungus Cryphonectria parasitica has been motivated largely by the potential for biological control of chestnut blight with fungal viruses that cause hypovirulence. Earlier studies gave valuable insights into the correlation between diversity of vegetative compatibility groups and transmission of hypovirulence viruses. However, inferences about evolutionary processes affecting populations were not possible because vegetative compatibility groups are not genetically defined. Using restriction fragment length polymorphism markers, however, progress has been made in studying the origin of C. parasitica in North America, gene flow among populations, dispersal within populations, and recombination and the mating system. Cryphonectria parasitica populations in North America are genetically more similar to populations in Japan than in China, which is consistent with previous speculations that this fungus was introduced from Japan. Populations in China and Japan are quite different, suggesting little or no gene flow between these areas. Restricted gene flow and genetic drift are probably the dominant evolutionary forces shaping North American populations, with approximately 20% of gene diversity due to differences among populations (GST = 0.20). Two populations of C. parasitica in Michigan and one population in Italy are primarily clonal in structure. In contrast, sexual reproduction appears to be common in populations in eastern North America, although most of these populations deviate significantly from random mating. Deviations from random mating are most likely due to self-fertilization (uniparental inbreeding), restricted dispersal of male gametes, and mating between individuals that are more closely related genetically than would be expected by chance (biparental inbreeding). Aggregations of similar genotypes in space suggest that populations of C. parasitica may be structured into genetic neighborhoods by restricted dispersal. Future research efforts in this system will explore isolation by distance and address questions of hypovirulence virus coevolution with its fungal host. Key words: Cryphonectria parasitica, Endothia parasitica, chestnut blight, genetic neighbourhoods, inbreeding.

Modelling the Influence of Hydrophobic Treatment on the Electrical Conductivity of Mortar and Brick

2015 ◽  
Vol 21 (2-3) ◽  
pp. 67-73 ◽  
Author(s):  
Kathrin A. Otten ◽  
Klaus Littmann ◽  
Ragna L. Fege ◽  
Xenia Oremek
Keyword(s):  
Moisture Content ◽  
Surface Treatment ◽  
Electrical Resistance ◽  
Building Materials ◽  
Outer Part ◽  
Water Repellent ◽  
Data Logging ◽  
Measuring Point ◽  
Moisture Contents ◽  
Using Data

Abstract This study evaluates the suitability of electrical resistance-based moisture content measurements, which are known to guarantee reliable values for moisture contents of wood, when applied to selected mineral building materials with and without water-repellent treatment. For the testing specimens of cement – mortar and solid brick were produced – the water-repellent treatment for the mortar specimens was carried out both by internal hydrophobization and surface treatment, while the bricks were hydrophobized by surface treatment only. For the measurements of electrical resistance electrodes were inserted into the specimens. For this purpose a borehole was drilled and the measuring point at the tip of the electrodes was glued conductively into the material. The remaining outer part of the electrodes was sealed with electrically isolating glue in order to establish a conductive connection in the middle of the specimens only. After storage at different relative humidity, the electrical resistance of the specimens was recorded using data logging devices. Based on gravimetrically measured moisture contents resistance characteristics for each material were established. A satisfying accuracy resulting from the comparison between gravimetrically measured and mathematically calculated material moisture contents confirmed the suitability of electrical resistance based moisture content measurements for selected treated and untreated mineral materials.

Measuring resistance of chestnut trees to chestnut blight

1992 ◽  
Vol 22 (4) ◽  
pp. 568-571 ◽  
Author(s):  
Sandra L. Anagnostakis
Keyword(s):  
Quantitative Assessment ◽  
First Generation ◽  
Chinese American ◽  
American Chestnut ◽  
Chestnut Blight ◽  
Japanese American ◽  
Individual Tree ◽  
Chestnut Blight Fungus ◽  
Tree Resistance ◽  
Virulent Strains

Four species of chestnut trees and four kinds of hybrids were inoculated with two virulent strains of the chestnut blight fungus (Cryphonectriaparasitica (Murr.) Barr). Rate of canker expansion was measured over 114 days (June–September), and rate change was used as a quantitative assessment of individual tree resistance. Cankers on two typical American chestnut trees (Castaneadentata (Marsh.) Borkh.) expanded at a rate of 1 mm/day. Expansion rates on Chinese chestnut (Castaneamollissima Blume) ranged from 0.2 to 0.6 mm/day, and the rates on two Japanese chestnut trees (Castaneacrenata Siebold & Zucc.) were 0.08 to 0.2 mm/day. Our single Henry chestnut (Castaneahenryi (Skan) Reh. & Wilson) tree allowed rates of 0.3 and 0.8 mm/day. Most rates on American–Chinese and Japanese–American hybrids were from intermediate between rates on Asian and American trees to near the rates on American trees. However, a first-generation backcross of Chinese–American × American only allowed expansion rates of 0.3 and 0.4 mm/day, similar to the lowest rates on Asian trees.

Spatial pattern analysis of vegetative compatibility groups in the chestnut blight fungus, Cryphonectria parasitica

1991 ◽  
Vol 69 (7) ◽  
pp. 1407-1413 ◽  
Author(s):  
Michael G. Milgroom ◽  
William L. MacDonald ◽  
Mark L. Double
Keyword(s):  
Average Distance ◽  
Cryphonectria Parasitica ◽  
Mantel Test ◽  
Vegetative Compatibility ◽  
Chestnut Blight ◽  
Spatial Pattern Analysis ◽  
Vegetative Compatibility Groups ◽  
Clear Cut ◽  
Chestnut Blight Fungus ◽  
Endothia Parasitica

Vegetative compatibility groups were determined for 914 isolates of the chestnut blight fungus, Cryphonectria (Endothia) parasitica, collected over a 5-year period from American chestnut trees in eight regenerating clear-cut plots. We tested the hypothesis that the average distance between individuals in the same vegetative compatibility group is not different from the average distance between individuals with vegetative compatibility assigned at random. Nonrandom patterns were detected in all plots at least once during the study, indicating that vegetative compatibility groups were often aggregated. However, when multiple occurrences of vegetative compatibility groups on the same tree were eliminated from the analysis, there was only one test (out of 98 in total) in which the null hypothesis was rejected. We conclude that nonrandom patterns of vegetative compatibility groups are due primarily to multiple occurrences of vegetative compatibility groups on the same trees. Nearly half of all new cankers detected once the epidemic got started were in the same vegetative compatibility groups as cankers previously resident on the same tree. These data are consistent with the hypothesis that populations of C. parasitica are partly clonal in structure. Key words: Endothia parasitica, hypovirulence, Mantel test, matrix comparison, spatial autocorrelation.

Characterizing soil aeration with a platinum microelectrode. II. Response under controlled soil physical conditions

Soil Research ◽  
1966 ◽  
Vol 4 (2) ◽  
pp. 103 ◽  
Author(s):  
DS McIntyre
Keyword(s):  
Moisture Content ◽  
Applied Voltage ◽  
Linear Relation ◽  
Electrical Resistance ◽  
Soil Aeration ◽  
Physical Conditions ◽  
Moisture Contents ◽  
Current Voltage ◽  
Effective Voltage ◽  
Aeration Conditions

Platinum microelectrode currents were measured in glass beads and two soils each at two different moisture contents. Diffusivity was kept constant for each soil at each moisture content but oxygen content was varied by changing the composition of the aerating gas. Results showed that current was strongly dependent on voltage; no plateau appeared in the current-voltage curves, but when comparison was made at constant effective voltage, rather than at constant applied voltage, a linear relation existed between current and oxygen concentration up to 21%. Electrical resistance of the soil was measured to allow comparison at constant effective voltage. Oxygen flux calculated at constant effective voltage, unlike that at constant applied voltage, is characteristic of soil aeration conditions irrespective of other physical properties, provided the moisture content of the soil is sufficiently high for satisfactory operation of the method.

Sign in / Sign up

Export Citation Format

Share Document