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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. Tree...

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...

In a pot experiment with strawberry plants (cv. Cambridge Favourite), two isolates (Th1 and Th2) of Trichoderma harzianum were tested individually and in combination for their efficacy against the root rot pathogen Armillaria mellea. Similarly, an effective isolate of Dactylium dendroides, the ‘Shi-itake Pathogen’ (SP), was combined with isolates of T. harzianum, T. viride, T. hamatum and Chaetomium olivaceum for the same purpose. Isolate Th2 performed better alone than in combination with isolate Thl, protecting 75% of the plants from death during the experiment lasting 413 days. None of the plants treated with Thl alone or Thl and Th2 together survived until the end of the experiment. The presence of SP had a significant (p < 0.05) effect on the survival of the plants. The median survival time in the presence of SP was 299.5 days compared with 206.0 days in its absence. At the end of the experiment, which lasted 534 days, 41.7% of the plants treated with SP survived compared with only 16.7% whe...

In a glasshouse experiment using potted strawberry plants (cv. Cambridge Favourite) as hosts, the effect of selected fungal antagonists grown on 25 or 50 g of mushroom compost containing autoclaved mycelia of Agaricus bisporus, or wheat bran was evaluated against Armillaria mellea. Another glasshouse experiment tested the effect of application time of the antagonists in relation to inoculations with the pathogen. A significant interaction was found between the antagonists, substrates and dose rates. All the plants treated with Chaetomium olivaceum isolate Co on 50 g wheat bran survived until the end of the experiment which lasted 482 days, while none of them survived when this antagonist was added to the roots of the plants on 25 g wheat bran or 25 or 50 g mushroom compost. Dactylium dendroides isolate SP had a similar effect, although with a lower host survival rate of 33.3%. Trichoderma hamatum isolate Tham1 and T. harzianum isolate Th23 protected 33.3% of the plants when added on 50 g and none...

Several in vitro and in vivo experiments were conducted to develop an effective technique for culturing potential fungal antagonists (isolates of Trichoderma harzianum, Dactylium dendroides, Chaetomium olivaceum and one unidentified fungus) selected for activity against Armillaria mellea. The antagonists were inoculated onto (l) live spawn of the oyster mushroom (Pleurotus ostreatus), (2) extra-moistened or sucrose-enriched mushroom composts containing living or autoclaved mycelia of P. ostreatus or Agaricus bisporus (button mushroom), (3) pasteurized compost with or without A. bisporus mycelium, wheat bran, wheat germ and (4) spent mushroom composts with living mycelia of A. bisporus, P. ostreatus or Lentinus edodes (the Shiitake mushroom). In one experiment, a representative antagonist (isolate Th2 of T. harzianum) was grown together with the A. bisporus mycelium, while in another one, the antagonist was first grown on wheat germ or wheat bran and then on mushroom compost with living mycelium o...

The interaction of 11 Trichoderma isolates against Armillaria root rot fungus of tea was investigated. Most isolates significantly inhibited the growth of Armillaria. The highest inhibition was noted with one of the isolates of T. koningii, T. longibrachiatum and T. harzianum. The isolates with highest inhibitory properties tended to produce a pigment into the nutrient broth. The implications of these results in view of the future management strategies of Armillaria root rot of tea in Kenya are discussed.

Mating experiments were conducted with 30 California isolates of Armillaria species to determine their intersterility grouping. Basidiomes were collected from a variety of coniferous and ha...

Armillaria mellea was once thought to be a morphologically variable species with a wide distri- bution and a very broad host range. The relatively recent development of an indirect assessment of sex- ual incompatibility in Armillaria has led to identifi- cation of biological species within A. mellea s. 1. Par- tial intergenic spacer region (IGS) sequences of the ribosomal RNA (rRNA) operon have been deter- mined for most of the Northern Hemisphere species of Armillaria, but not for A. mellea s. s. The aim of this study was to determine the phylogenetic rela- tionships among isolates of A. mellea s. s. based on DNA sequences from the IGS as well as the internal transcribed spacer (ITS) regions. The IGS and the ITS sequence data indicate that A. mellea is highly variable but phylogenetically distant from the other species of Armillaria, and there are four separate groups of A. mellea distinguished by their geograph- ical origin: Asia, western North America, eastern North America and Europe. The data suggest that A. mellea populations from different regions are genet- ically isolated and may be in the process of specia- tion.

Summary Colour aerial photography at scales of 1:3000 and 1:6000 was used to identify 86.6% and 68% respectively of the 5.03 ha affected by Armillaria root rot in a 32 ha mixed species eucalypt stand, located in central Victoria. At the 1:3000 scale more of the infected area was detected and correctly mapped but a larger proportion of the healthy area was incorrectly classified as infected.

An historical sketch of several forest diseases in South Africa was compiled after a search of accessions at the National Collection of Fungi, correspondence housed at the Forestry Branch's archives, and other published and unpublished reports. Diplodia dieback was first found in 1909 in the eastern Cape; had been reported from all forest regions by 1938; caused Pinus radiata to be abandoned as a commercial species in the summer rainfall region during the 1920s; became an important problem with Pinus patula between 1930 and 1941, before which time this host was considered highly resistant. Armillaria root rot has been found primarily in the Northern and Eastern Transvaal and in Zululand; caused growers to temporarily consider abandoning afforestation in the Northern Transvaal during the early 1930s; has been most severe in first rotation stands on sites where certain indigenous tree species (particularly, Parinari curatellifolia) previously grew; has been caused by an as yet undetermined species ...