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Western redcedar (WRC) trees of 48-49 years in age grown in monoculture and in admixtures with birch, Douglas-fir and pine in the interior of British Columbia were sampled for wood density and the presence and level of damage from butt decay initiated by Armillaria ostoyae in stumped and unstumped plots. Stump removal reduced butt decay incidence in WRC from 18% to 2% and damage from 3.5% of the diameter at base to 0.3% compared to when stumps remained. External lesions on tree bases caused by Armillaria root disease increased the probability of WRC stems having butt decay by 1.25 times for an average-sized lesion. The incidence of butt decay and the level of internal damage to WRC in sampled plots was not related to admixture, tree size or site index. Stump removal controlled the inoculum of Armillaria root disease, thereby reducing incidence and size of WRC basal lesions that probably act as infection courts for other fungi causing butt decay. WRC trees grown in monoculture or with birch had the highest wood densities of all planting mixes tested. Wood density in WRC was lowest at the outer edges of individual WRC trees, in larger trees, and in plots where stumps had not been removed. The lower density WRC wood is thought to occur by overtopping from fast-growing species in admixture and depletion of soil moisture affecting latewood formation. This is a first report of stump removal affecting butt decay and admixture affecting wood density in WRC. [ABSTRACT FROM AUTHOR]

Trunk infusion of peach with propiconazole has been suggested as a potential strategy to protect roots from colonization by Armillaria species. In the present study, we investigated the persistence of propiconazole in peach roots following fall infusions and its potential for Armillaria root rot control in a commercial peach orchard. Four 12-year-old trees were infused with either 2 liters of a propiconazole solution at 0.4 mg ml-1 or water in September 2007. Bark tissue collected from primary roots of propiconazole-infused trees 48 hr and 6 and 12 months after infusion and analyzed using gas chromatography-mass spectroscopy contained 6.4, 1.4, and 0.9 μg propiconazole per gram fresh bark, respectively. Asymptomatic trees adjacent to trees that had died from Armillaria root rot (protective treatment) and symptomatic but alive trees (curative treatment) were infused with 1 liter of a propiconazole solution (0.4 mg ml-1) in spring and fall of 2008 and 2009 at a commercial peach orchard planted in 2005. Trees were rated for Armillaria root rot severity 6, 12, 24, and 36 months post-infusion. In the protective treatment, the survival rate in both non-infused and infused trees was 80% 36 months post-infusion. However, more (60%) of the propiconazole-infused trees remained asymptomatic compared to the control trees (30%). A significant difference was observed between the non-infused and propiconazole-infused trees following curative treatment. None of the control trees were alive after 36 months compared to 40% of propiconazole-infused trees. We conclude that fall infusion of peripheral trees of infection centers with propiconazole can slow the expansion of Armillaria root rot infection centers in commercial peach orchards. [ABSTRACT FROM AUTHOR]

Symptoms of Armillaria root rot were observed on the herbaceous ornamental, Hemerocallis sp. (daylily), in a residential area in Walhalla, South Carolina, which was surrounded by dense, hardwood forest that also contained diseased hosts. Our objectives were to describe a natural occurrence of Armillaria root rot on daylily, a newly discovered host for the pathogen, and to characterize the Armillaria species involved. To characterize the Armillaria species collected from daylily, we used all available methods, including both traditional (sexual compatibility tests, basidiome morphology) and molecular (phylogenetic analyses of rDNA internal transcribed spacer, ITS, and intergenic spacer I, IGS-I) approaches. The presence of rhizomorphs in the topsoil of daylily beds and on the roots of symptomatic daylilies, coupled with our finding of identical ITS1 sequences among isolates originating from each of a rhizomorph, a daylily, and a neighbouring dogwood, suggests that Armillaria rhizomorphs had spread from native hosts to infect the daylilies. Basidiocarp morphology and basidiospore size best matched that documented for A. gallica. However, rDNA sequence analysis and sexual compatibility were not 100% conclusive. Phylogenetic analysis of ITS sequences revealed that the unknown Armillaria isolates were most closely related to A. calvescens and A. gallica. Analysis of IGS-I sequences was even less informative, grouping our isolates with A. cepistipes, A. gallica and A. sinapina. Sexual compatibility (mating) tests revealed that haploid isolates from daylily were compatible with three of the A. gallica tester isolates, but also one of the A. calvescens tester isolates. Our findings suggest a possible southerly distribution and expanded host range for A. gallica, and raise further questions about the Armillaria species concept as it pertains to the two closely related species, A. calvescens and A. gallica. [ABSTRACT FROM AUTHOR]

Nonaerated compost teas produced from composted green waste of various ages were used to challenge the growth of Armillaria mellea, the causal agent of the Honey fungus white root-rot disease. Three trials were carried out: in vitro agar based assays over a period of 16 days employing repeated application of the teas; timber billet trials over a period of 30 days using a single pretreatment; and a pot trial using deliberately infected young beech trees watered with compost teas at 4 day intervals. The compost samples used were from a commercial source and sampled after storage for one, two, three and six months. Control treatments used distilled water applications in place of compost teas. In all cases compost tea applications inhibited the growth of rhizomorphs significantly and resulted in changes in their morphology. In the pot trials none of the treatments prevented infection, but rather slowed the development of wilt symptoms. Age of compost had an effect in all trials. The results indicate that such treatments may have potential in the treatment of this damaging infection and also highlight the significance of the maturity of green waste composts and teas proposed for the suppression of plant diseases. [ABSTRACT FROM AUTHOR]

Provides information on a study that identified a collection of isolates from dying trees, showing typical symptoms of Armillaria root rot in various parts of South America and Indo-Malaysia. Methodology of the study; Results and discussion on the study.

Focuses on a study which described several species of the Kenyan root rot pathogen Armillaria. Materials and methods; Results; Discussion.