Progress 06/01/07 to 10/01/12
Outputs
OUTPUTS: The ecology, species distribution, and population structure of Armillaria was investigated in the forests of Massachusetts. From 64 plots at 16 sites, 640 isolates of Armillaria were collected from six forest types (northern hardwoods, mixed oak, pitch pine, white pine, white pine/mixed oak, and eastern hemlock). Armillaria gallica proved to be the most abundant species, making up 316 of 640 (52 percent) of all isolations. This was followed by A. solidipes (219 of 640; 34 percent), A. mellea (46 of 640; 7 percent), A. calvescens (36 of 640; 6 percent), A. gemina (16 of 640; 3 percent), and A. sinapina (7 of 640; 1percent). Armillaria gallica was routinely encountered causing significant decay of the lower bole on living hardwood hosts, especially oaks. The population structure of 153 isolates of A. gallica collected from mixed oak forests was investigated using amplified fragment length polymorphisms (AFLPs). From a total sampling area of 4.51 ha, 38 AFLP genotypes were discovered, yielding a figure of eight genets per hectare with the average A. gallica genet occupying 0.13 ha. When the effects of hydrolyzable tannins on in vitro growth were compared between A. calvescens and A. gallica, it was A. gallica that appeared better at oxidizing and metabolizing commercial tannins (tannic acid and gallic acid) along with black oak root bark extracts. This was determined through measurements of colony area and dry biomass, and suggests that A. gallica may be a better adapted pathogen of oak. In order to more accurately distinguish between isolates of A. calvescens and A. gallica, a three-gene phylogeny was reconstructed, using partial sequences of the elongation factor 1-alpha (tef1), RNA polymerase II (rpb2) and nuclear large subunit (nLSU) genes. After comparing 12 isolates each of A. calvescens and A. gallica that originated from across northeastern North America, only the tef1 gene could accurately distinguish these two species. Five single nucleotide polymorphisms were present between the two species and maximum likelihood and maximum parsimony methods grouped A. calvescens and A. gallica into monophyletic clades. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Several of our findings have dispel and or clarify widely held beliefs concerning host specificity, virulence, and occurrence. For example, Armillaria mellea is widely regarded as a pathogen of hardwoods only, yet it was found 16 times from eastern white pine, the most isolations for any species on this host. Armillaria gemina was found infecting eastern hemlock on 3 occasions yet previously it was never reported from conifers. With respect to virulence, A. gallica is commonly referred to as a saprophyte, only capable of colonizing dead material. We found A. gallica routinely causing extensive decay on living hardwoods and conifers. Because we have sampled a large number of isolates from a variety of forest types, our study will significantly advance our understanding of Armillaria in northern temperate forests.
Publications
- No publications reported this period
|
Progress 10/01/10 to 09/30/11
Outputs
OUTPUTS: The ecology, species distribution, and population structure of Armillaria was investigated in the forests of Massachusetts. From 64 plots at 16 sites, 640 isolates of Armillaria were collected from six forest types (northern hardwoods, mixed oak, pitch pine, white pine, white pine/mixed oak, and eastern hemlock). Armillaria gallica proved to be the most abundant species, making up 316 of 640 (52 percent) of all isolations. This was followed by A. solidipes (219 of 640; 34 percent), A. mellea (46 of 640; 7 percent), A. calvescens (36 of 640; 6 percent), A. gemina (16 of 640; 3 percent), and A. sinapina (7 of 640; 1percent). Armillaria gallica was routinely encountered causing significant decay of the lower bole on living hardwood hosts, especially oaks. The population structure of 153 isolates of A. gallica collected from mixed oak forests was investigated using amplified fragment length polymorphisms (AFLPs). From a total sampling area of 4.51 ha, 38 AFLP genotypes were discovered, yielding a figure of eight genets per hectare with the average A. gallica genet occupying 0.13 ha. When the effects of hydrolyzable tannins on in vitro growth were compared between A. calvescens and A. gallica, it was A. gallica that appeared better at oxidizing and metabolizing commercial tannins (tannic acid and gallic acid) along with black oak root bark extracts. This was determined through measurements of colony area and dry biomass, and suggests that A. gallica may be a better adapted pathogen of oak. In order to more accurately distinguish between isolates of A. calvescens and A. gallica, a three-gene phylogeny was reconstructed, using partial sequences of the elongation factor 1-alpha (tef1), RNA polymerase II (rpb2) and nuclear large subunit (nLSU) genes. After comparing 12 isolates each of A. calvescens and A. gallica that originated from across northeastern North America, only the tef1 gene could accurately distinguish these two species. Five single nucleotide polymorphisms were present between the two species and maximum likelihood and maximum parsimony methods grouped A. calvescens and A. gallica into monophyletic clades. PARTICIPANTS: Ken Gooch, forest health program supervisor, assisted in securing necessary permits to carry out field research in Massachusetts state forests. Steve Ward, Quabbin reservoir management forester, assisted in locating study sites in oak/hickory forests within the Quabbin watershed. TARGET AUDIENCES: State and extension foresters, forest landowners, timber harvesters, forest ecologists and mycologists. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Several of our findings dispel and or clarify widely held beliefs concerning host specificity, virulence, and occurrence. For example, Armillaria mellea is widely regarded as a pathogen of hardwoods only, yet it was found 16 times from eastern white pine, the most isolations for any species on this host. Armillaria gemina was found infecting eastern hemlock on 3 occasions yet previously it was never reported from conifers. With respect to virulence, A. gallica is commonly referred to as a saprophyte, only capable of colonizing dead material. We found A. gallica routinely causing extensive decay on living hardwoods and conifers. Because we have sampled a large number of isolates from a variety of forest types, our study will significantly advance our understanding of Armillaria in northern temperate forests.
Publications
- Brazee, N.J., and Wick, R.L. 2009. Armillaria species distribution on symptomatic hosts in northern hardwood and mixed oak forests in western Massachusetts. Forest Ecology and Management 258(7): 1605-1612.
- Brazee, N.J., and Wick, R.L. 2011. Armillaria species distribution and site relationships in Pinus- and Tsuga-dominated forests in Massachusetts. Canadian Journal of Forest Research 41(7): 1477-1490.
- Brazee, N.J., Marra, R.E., and Wick, R.L. 2011. Genotypic diversity of Armillaria gallica from mixed oak forests in Massachusetts. Mycologia doi: 10.3852/11-113 (published online September 13, 2011)
- Brazee, N.J., Wick, R.L., and Wargo, P.M. 2011. Effects of hydrolyzable tannins on in vitro growth of Armillaria calvescens and A. gallica. Plant Disease 95(10): 1255-1262.
- Brazee, N.J., Hulvey, J.P., and Wick, R.L. 2011. Evaluation of tef1, rbp2, and nLSU sequences for identification of isolates representing Armillaria calvescens and A. gallica from northeastern North America. Fungal Biology 115: 741-749.
|
Progress 10/01/09 to 09/30/10
Outputs
OUTPUTS: Armillaria is the most important root rot pathogen in the forests of Massachusetts, yet little is known about how the six species in this area are distributed by forest type. In total, 666 isolates of Armillaria were collected from 16 sites spanning six forest types (northern hardwoods, oak/hickory, hemlock, white pine, white pine - oak, and pitch pine). Isolates have been identified with a recently developed PCR-RFLP protocol and from elongation factor 1-alpha sequences. Several of our findings have been contradictory to the widely held beliefs concerning host specificity, virulence, and occurrence. For example, A. mellea is widely regarded as a pathogen of hardwoods only, yet it has been located regularly on eastern white pine and pitch pine. In regards to virulence, A. gallica is frequently referred to as a saprophyte, only capable of colonizing dead organic matter. We have found A. gallica routinely causing decay to living hardwoods and conifers. Because we sampled such a large number of isolates from a variety of forest types, our study will significantly advance the understanding of Armillaria in northern temperate forests. To better understand the population of A. gallica, we genotyped 153 isolates collected from oak forests using amplified fragment length polymorphism. We have detected 38 distinct AFLP genotypes within our population, and results from analysis of molecular variation and the Mantel test, used to test the isolation by distance theory, are both highly significant (p less than 0.001, and p less than 0.001, respectively). From the A. gallica population, 70 percent of the molecular variation came from within sites (subpopulations) and a neighbor-joining tree produced from a genetic distance matrix shows an irregular clustering of genotypes, suggesting a random mating pattern. Results from a study designed to test whether A. gallica is better than A. calvescens at overcoming the chemical defenses of Quercus spp. has shown that A. gallica is indeed better at oxidizing and metabolizing tannic acid, gallic acid, and Q. velutina root bark extracts. This study helps to explain why A. calvescens, a species that is very closely related to A. gallica, is not found in mixed oak forest, yet thrives in northern hardwoods. PARTICIPANTS: Charles Burnham, forest health program supervisor, assisted in securing necessary permits to carry out field research in Massachusetts state forests. Steve Ward, Quabbin reservoir management forester, assisted in locating study sites in oak/hickory forests within the Quabbin watershed. TARGET AUDIENCES: State and extension foresters, forest landowners, timber harvesters PROJECT MODIFICATIONS: a Bio-Imaging system was repaired to advance research during the 2010 calendar year.
Impacts
Armillaria species distribution in northern temperate forest ecosystems is better understood.
Publications
- Brazee, N.J., and Wick, R.L. 2010. Pest Alert: Armillaria root disease. Massachusetts Department of Conservation and Recreation, Amherst, MA. 1 p.
- Brazee, N.J. and R.L. Wick. 2010. Armillaria species distribution and site relationships in Pinus- and Tsuga-dominated forests in Massachusetts. Presented at the 70th Annual Meeting, Northeastern Division of the American Phytopathological Society, Northampton, MA. October 27-29, 2010.
- Brazee, N.J. and R.L. Wick. 2010. Is Armillaria gallica better adapted to overcome the host defenses of Quercus spp. than A. calvescens An analysis of hydrolyzable tannins on in vitro growth. Presented at the 72nd Annual Meeting of the Northeastern Forest Pest Council, York Harbor, ME. March 16-17, 2010.
|
Progress 10/01/08 to 09/30/09
Outputs
OUTPUTS: Armillaria is the most important root rot pathogen in the forests of Massachusetts, yet little is known about how the six species in this area are distributed by forest type. To date, 544 isolates of Armillaria have been collected from 13 sites spanning six forest types (northern hardwoods, oak/hickory, hemlock, white pine, white pine - oak, and pitch pine). In total, 660 isolates will be collected from 16 sites. Isolates have been identified with a recently developed PCR-RFLP protocol. To better understand the population of A. gallica, we are genotyping isolates collected from oak forests using amplified fragment length polymorphism (AFLP). The AFLP dataset is nearly complete and will provide significant insight into how the population is dispersed on the landscape. This species is a serious pathogen of oaks and during the period when gypsy moth was defoliating wide tracts of forest, A. gallica was killing many of the stressed trees. Additional data on how individual Armillaria species overcome the chemical defenses of Quercus spp. is almost completed and will provide greater insight into how the fungus behaves. Isolates are being grown on polyphenolic-supplemented media (solid and broth) to measure colony area and biomass. PARTICIPANTS: Charles Burnham, forest health program supervisor, assisted in securing necessary permits to carry out field research in Massachusetts state forests. Steve Ward, Quabbin reservoir management forester, assisted in locating study sites in oak/hickory forests within the Quabbin watershed. TARGET AUDIENCES: State and extension foresters, forest landowners, timber harvesters PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Several of our findings have been contradictory to the widely held beliefs concerning host specificity, virulence, and occurrence. For example, A. mellea is widely regarded as a pathogen of hardwoods only, yet it was found 16 times from eastern white pine, the most isolations for any species on this host. Armillaria gemina, which has never been isolated from a conifer, was found infecting eastern hemlock on 3 occasions. In regards to virulence, A. gallica is commonly referred to as a saprophyte, only capable of colonizing dead material. We have found A. gallica routinely causing extensive decay on living hardwoods and conifers. Because we are sampling such a large number of isolates from a variety of forest types, our study will significantly advance our understanding of Armillaria in northern temperate forests.
Publications
- Brazee, N.J., and Wick, R.L. 2009. Armillaria species distribution on symptomatic hosts in northern hardwood and mixed oak forests in western Massachusetts. Forest Ecology and Management 258(7): 1605-1612.
|
Progress 10/01/07 to 09/30/08
Outputs
OUTPUTS: Armillaria is the most important root rot pathogen in the forests of Massachusetts, yet little is known about how the six species in this area are distributed by forest type. To date, 420 isolates of Armillaria have been collected from 12 sites spanning five forest types (northern hardwoods, oak/hickory, hemlock, oak/pine, pitch pine/scrub oak). 160 isolates have been identified from 4 northern hardwood stands in northwestern Massachusetts. Armillaria gallica was the most abundant species across all 4 sites, comprising 88/160 isolates (55 percent). This species is an aggressive root and butt rot pathogen of a broad array of trees, and was isolated most often from sugar and red maples. Armillaria calvescens was the second most abundant species (29/160; 18 percent), followed by A. gemina (18/160; 11 percent), A. ostoyae (18/160; 11 percent), and A. sinapina (7/160; 4 percent). Armillaria mellea was not encountered in any study sites. Considerable variation in species incidence was encountered within and across plots for most sites. Three or more species were found within a single plot on 8 occasions. 91% of the collected isolates have come from living trees. All four sites were uniform in forest composition, with only minor variations in soil type and parent material. The species distribution at Mount Greylock was particularly interesting, as A. ostoyae was the most abundant species encountered (16/40; 40 percent). Armillaria ostoyae is an aggressive, primary pathogen usually found in coniferous forests. It was hypothesized that the presence of red spruce / balsam fir forests occupying upper elevations of the Greylock range were dominated by A. ostoyae and this population was filtering downslope into northern hardwood stands. Yet, multiple attempts to locate Armillaria in this spruce/fir site were unsuccessful. Instead, another rhizomorph producing root decay fungus was found in abundance in the spruce/fir site, Xeromphalina. The role of Xeromphalina as a forest pathogen has been little studied, yet it appears to be an aggressive root and butt rot pathogen of Abies balsamea. Armillaria gemina, was encountered in 10/40 isolations (25 percent) at Mount Greylock. This species was found causing significant butt rot to live trees, and a growing body of evidence suggests this species may be as virulent as A. ostoyae. Microsatellite genotyping is underway to determine the population structure of A. gallica. This is the most abundant species across northern hardwoods in western Massachusetts, and is capable of causing significant monetary losses to timber harvesting operations. While many of the trees infected by A. gallica were still alive, the butt log was heavily decayed, significantly reducing the economic value of the tree. PARTICIPANTS: Charles Burnham, forest health program supervisor, assisted in securing necessary permits to carry out field research in Massachusetts state forests. Steve Ward, Quabbin reservoir management forester, assisted in locating study sites in oak/hickory forests within the Quabbin watershed TARGET AUDIENCES: State and extension foresters, forest landowners, timber harvesters PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Armillaria has been located across the state in 5 separate forest types, illustrating the ubiquity of this fungus in Massachusetts. It's primarily causing butt rot on sugar and red maple and northern hardwood forests, and butt rot on black and white oak in oak/hickory forests.
Publications
- No publications reported this period
|
Progress 10/01/06 to 09/30/07
Outputs
OUTPUTS: Armillaria is the most important root and butt pathogen in the forests of Massachusetts, yet little is known about how the six species in this area are distributed by forest type. To date, 220 isolates of Armillaria have been collected from 22 plots spanning two forest types (northern hardwoods and oak/hickory). Ninety percent of collected isolates have come from living trees. A grand total of 960 isolates from 6 forest types will ultimately be collected. Within each plot, 100 square meter rectangular plots have been established and all live trees more than 5cm in diameter at breast height (dbh) have been sampled for species, dbh, height, and crown class. Isolates of Armillaria have been cultured on a selective medium and are being prepared for DNA extraction and species identification using molecular-based techniques. Specifically, sequence characterized amplified regions (SCAR) primers will be developed to identify species. Within northern hardwood forests, Armillaria is
most active causing butt rot of sugar and red maple. Large, gaping wounds on the base of mature trees were routinely encountered in 16 plots spanning 4 sites. Within oak/hickory forests, Armillaria is most often encountered causing butt rot on black and white oak. Infections are not nearly as severe as in northern hardwood forests, but have been found routinely in 6 plots across 2 sites.
PARTICIPANTS: Charles Burnham, forest health program supervisor, assisted in securing necessary permits to carry out field research in Massachusetts state forests. Steve Ward, Quabbin reservoir management forester, assisted in locating study sites in oak/hickory forests within the Quabbin watershed.
Impacts
Armillaria is common in both northern hardwood and oak/hickory forests in Massachusetts. It's primarily causing butt rot on sugar and red maple and northern hardwood forests, and butt rot on black and white oak in oak/hickory forests.
Publications
- No publications reported this period
|
|