scholarly journals Armillaria Root Disease Inoculum Remaining in Young Ontario Conifer Plantations Following Root Raking or Madge Rotoclearing

1998 ◽  
Vol 15 (4) ◽  
pp. 191-196 ◽  
Author(s):  
Johann N. Bruhn ◽  
Jeanne D. Mihail ◽  
Timothy R. Meyer
Keyword(s):  
Woody Debris ◽  
Site Preparation ◽  
Root Disease ◽  
Northern Ontario ◽  
Fallow Period ◽  
Disease Mortality ◽  
Lethal Infection ◽  
Woody Root ◽  
Armillaria Root Disease ◽  
Apparently Healthy

Abstract Armillaria ostoyae causes a destructive root disease in northern conifers. Most infections result from root invasions by rhizomorphs growing through the soil from previously colonized stump and woody root debris. Armillaria longevity in woody debris is related to the colonized volume. Stump and root removal by root raking alone often does not satisfactorily reduce subsequent root disease mortality. This investigation characterized residual woody debris volumes in three conifer seed orchards in northern Ontario. Site preparation for stump and root removal in two of the orchards consisted of root raking alone, vs. Madge Rotoclear™ treatment ("rotoclearing") in the third orchard. Fallow periods between site preparation and planting were 1, 5, and 8 yr in the three orchards, respectively. Mortality related to colonized residual woody debris is continuing in the raked orchards, but appears to have ended in the rotocleared orchard. Root systems of 32 orchard trees recently killed by Armillaria root disease and 9 apparently healthy (otherwise comparable) trees were excavated. Regardless of site preparation method, Armillaria-killed trees were associated with greater total volumes of residual woody debris (comprising larger pieces on average) than were healthy trees. Also, healthy trees in the rotocleared orchard were associated with smaller debris pieces on average than were healthy trees in the root-raked orchard. Size of individual woody debris pieces which contained viable A. ostoyae was highly variable. Even small pieces of colonized debris close to a root crown were apparently capable of causing lethal infection. Nevertheless, compared to root raking, rotoclearing apparently breaks A. ostoyae-colonized woody debris into smaller pieces resulting in more rapid displacement of A. ostoyae. We conclude that rotoclearing followed by a fallow period of 8 yr before planting merits consideration as an inoculum reduction treatment for site preparation. A 10 yr fallow period might have prevented nearly all root disease mortality under the conditions of this study. North. J. Appl. For. 15(4):191-196.

scholarly journals Distribution, Severity, and Spread of Armillaria Root Disease in Kenya Tea Plantations

Plant Disease ◽  
1997 ◽  
Vol 81 (2) ◽  
pp. 133-137 ◽  
Author(s):  
J. M. Onsando ◽  
P. M. Wargo ◽  
S. W. Waudo
Keyword(s):  
Disease Severity ◽  
Management Practice ◽  
Woody Debris ◽  
Root Disease ◽  
Disease Spread ◽  
Tree Roots ◽  
Tea Plantations ◽  
Armillaria Root Disease ◽  
Residual Tree ◽  
Tea Plants

Surveys for Armillaria root disease severity were conducted over a 5-year period in small tea farms (0.5 to 1.0 ha) in the 12 tea-growing districts of Kenya. The disease occurred in all tea districts, but severity was greater in the districts east of the Rift Valley. Disease severity was associated with relative amounts of residual woody debris, especially roots, from trees and shrubs present when the land was converted to tea plantations. Excavation of tea bushes in disease centers showed that infection of tea bushes occurred primarily by mycelial growth from residual tree roots and from infected tea roots rather than from rhizomorphs. Rhizomorphs were scarce, and rarely involved in infection. They were confined mostly to the surface of the residual tree roots and were found growing freely in the soil in only one tea district. Rhizomorphs were more abundant in higher elevation plantations than in lower elevation plantations, where they occurred only on residual tree roots in the deeper, cooler, moister levels of the soil. Inoculum from residual tree debris in the soil was the most important source of infection in plantations of seed origin. Secondary spread from infected tea plants to healthy ones was limited and disease centers were small. In tea plantations derived from clonal cuttings, secondary disease spread from infected to healthy tea plants was more important resulting in large disease centers or gaps due to plant death and removal. Currently, soil sanitation by thorough removal of roots of forest trees and prompt removal of infected tea bushes is the best available management practice.

scholarly journals First Report of an Armillaria Root Disease Pathogen, Armillaria gallica, Associated with Several New Hosts in Hawaii

Plant Disease ◽  
2010 ◽  
Vol 94 (12) ◽  
pp. 1503-1503 ◽  
Author(s):  
M.-S. Kim ◽  
J. W. Hanna ◽  
N. B. Klopfenstein
Keyword(s):  
Loblolly Pine ◽  
Tree Species ◽  
Forest Decline ◽  
Plant Pathogens ◽  
Root Disease ◽  
Native Forest ◽  
Monterey Pine ◽  
Armillaria Gallica ◽  
Armillaria Root Disease ◽  
Apparently Healthy

The loss and decline of native tree species caused by invasive plant pathogens is a major threat to the endangered endemic forests of the Hawaiian Islands (3). Thus, it is critical to characterize existing pathogens to evaluate potential invasiveness. In August 2005, rhizomorphs and mycelial bark fans of genet HI-4 were collected from dead/declining, mature trees of introduced Monterey pine (Pinus radiata) on the southern flank of Mauna Kea, Hawaii (approximately 19°42′55″N, 155°26′48″W, elevation 2,175 m). In March of 2008, three additional genets (HI-11, HI-13, and HI-16) were collected as rhizomorphs at a site named Pu'u La'au (west slope of the Mauna Kea Forest Reserve area, approximately 19°50′00″N, 155°35′35″W, elevation 2,275 to 2,550 m), approximately 20 km west-northwest of the HI-4 collection. These genets were collected from apparently healthy loblolly pine (Pinus taeda) that were introduced, apparently healthy māmane (Sophora chrysophylla; an endemic tree species of Hawaii), dead and dying māmane, and apparently healthy Methley plum (Prunus cerasifera × Prunus salicina) that was planted. All isolates were determined to have identical sequences in the intergenic spacer-1 rDNA region (GenBank Accession No. DQ995357). On the basis of somatic paring tests against North American Armillaria tester strains and 99% nucleotide sequence identities to GenBank Accession Nos. AY190245 and AY190246, these isolates were identified as Armillaria gallica. Past surveys have noted A. mellea sensu lato and A. nabsnona on numerous hosts in Hawaii, including māmane (3,4). However, to our knowledge, this is the first confirmed report of A. gallica in Hawaii, where it was found on māmane, Monterey pine, loblolly pine, and Methley plum. A. gallica has been widely categorized as a beneficial saprophyte, an opportunistic pathogen, or an aggressive pathogen (2). A recent study suggests that A. gallica can be highly pathogenic in some areas of the eastern United States and it is an important component of forest decline (2), especially under increasing stressors such as climate change. The isolation of A. gallica from declining stands on both introduced and endemic hosts under drought conditions suggests this pathogen is a contributing factor to forest decline on the island of Hawaii. Because the māmane tree is an important component of the native forest stands and essential to the endangered palila bird (Loxioides bailleui), which feeds almost exclusively on its green seeds (1), continued monitoring of Armillaria root disease is warranted. References: (1) P. C. Banko et al. J. Chem. Ecol. 28:1393, 2002. (2) N. J. Brazee and R. L. Wick. For. Ecol. Manage. 258:1605, 2009. (3) R. E. Burgan and R. E. Nelson. USDA For. Serv. Tech. Rep. PSW-3, 1972. (4) J. W. Hanna et al. Plant Dis. 91:634, 2007.

Inoculation of stumps with Hypholoma fasciculare as a possible means to control armillaria root disease

2000 ◽  
Vol 78 (1) ◽  
pp. 129-134 ◽  
Author(s):  
Bill Chapman ◽  
G Xiao
Keyword(s):  
Woody Debris ◽  
Root Disease ◽  
Tree Roots ◽  
Simple Method ◽  
Armillaria Ostoyae ◽  
Root Segments ◽  
Armillaria Root Disease ◽  
Hypholoma Fasciculare

Hypholoma fasciculare (Huds. ex Fr.) Kummer was paired with Armillaria ostoyae (Romagn.) Herink in a variety of ways in the laboratory and then it was inoculated onto A. ostoyae infected stumps in the field. The ability of H. fasciuclare colonies to overrun A. ostoyae colonies in culture was confirmed. Hypholoma fasciculare fully colonized discs of tree roots where A. ostoyae was well established, and prevented A. ostoyae from occupying root segments when both fungi were introduced simultaneously. A simple method for inoculating H. fasciculare into stumps is described, and data supporting successful field inoculations are presented. The ability of H. fasciculare to invade freshly killed stumps, even those occupied by Armillaria, is demonstrated, and it is speculated that the ability of this saprophyte to invade fresh stumps is dependent upon its inoculum potential.Key words: biocontrol, woody debris, fungal warfare, Armillaria ostoyae.

Using spatial and temporal patterns of Armillaria root disease to formulate management recommendations for Ontario's black spruce (Piceamariana) seed orchards

1996 ◽  
Vol 26 (2) ◽  
pp. 298-305 ◽  
Author(s):  
J.N. Bruhn ◽  
J.D. Mihail ◽  
T.R. Meyer
Keyword(s):  
Management Practices ◽  
Black Spruce ◽  
Root Disease ◽  
Forest Land ◽  
Spatial And Temporal Patterns ◽  
Seed Orchards ◽  
Disease Mortality ◽  
Armillaria Root Disease ◽  
Management Recommendations ◽  
Logistic Functions

Between 1982 and 1989, 22 black spruce (Piceamariana (Mill.) BSP) seed orchards were established on cleared jack pine (Pinusbanksiana Lamb.) forest land in northwest Ontario. These orchards were located on stressful sites for black spruce to hasten seed production. Mortality caused by Armillariaostoyae (Romagn.) Herink was observed in most of these orchards within 3 years of establishment. This study was initiated to quantitatively describe the temporal progress and spatial patterns of Armillaria root disease mortality in five representative orchards, to determine future operational management implications. In the four orchards where epidemics developed, temporal disease progress was nonlinear and was better described by the monomolecular function than by the Gompertz or logistic functions. Monomolecular rates of disease increase were 0.0062–0.0346. Applying these rates, we estimated that cumulative Armillaria root disease mortality will be 9–41% and 25–79%, at 20 and 50 years after planting, respectively. Armillaria root disease mortality was spatially aggregated in all four orchards. Trees adjacent to Armillaria-killed trees had an increased probability of mortality from Armillaria root disease. Successive epidemics may develop in these orchards; their timing and severity will be affected by orchard management practices. Measures of spruce family performance in these orchards are compromised by the aggregated distributions of different A. ostoyae genets and the root disease they cause.

scholarly journals Inoculum Reduction Measures to Manage Armillaria Root Disease in a Severely Infected Stand of Ponderosa Pine in South-Central Washington: 35-Year Results

2012 ◽  
Vol 27 (1) ◽  
pp. 25-29 ◽  
Author(s):  
Charles G. Shaw ◽  
D.W. Omdal ◽  
A. Ramsey-Kroll ◽  
L.F. Roth
Keyword(s):  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Root Disease ◽  
Intensive Treatment ◽  
Control Treatment ◽  
No Removal ◽  
South Central ◽  
Armillaria Root Disease ◽  
Different Levels ◽  
Maximum Removal

Abstract A stand of ponderosa pine (Pinus ponderosa) severely affected by Armillaria root disease was treated with five different levels of sanitation by root removal to reduce root disease losses in the regenerating stand. Treatments included the following: (1) all trees pushed over by machine, maximum removal of roots by machine ripping, and visible remaining roots removed by hand; (2) all trees pushed over by machine and maximum removal of roots by machine ripping; (3) all trees pushed over by machine with no further removal of roots; (4) smaller trees pushed over by machine but large stumps left, otherwise maximum removal of roots by machine ripping; and (5) all trees felled and removed by skidding, area cleared of slash, sod scalped, and no removal of roots. After 35 years, we found that the more intense and thorough root-removal treatments were generally more effective in reducing the occurrence of Armillaria root disease. However, even the most intensive treatment (treatment 1), which experienced significantly less disease than most other treatments, had 23% of the area expressing mortality. The only operationally feasible treatment (treatment 3) also reduced levels of mortality, but not significantly (40% mortality versus 52% in the control, treatment 5). Although these results support the concept that inoculum removal can reduce root disease levels, the treatment necessary to provide a meaningful reduction in disease loss does not seem to warrant its cost.

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