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(1993). Identification of Armillaria Species from New Hampshire. Mycologia: Vol. 85, No. 3, pp. 365-368.

Diploid-haploid pairings to identify field isolates of Armillaria to species generally rely on morphological differences between diploid and haploid colonies (flat and fluffy colonies, respectively) and morphological changes in haploid tester colonies. Presumably, the change in morphology of the haploid tester is due to diploidization. Isozyme markers, aconitase and glucosephosphate isomerase, were used to follow nuclear migration from putatively diploid isolates into a haploid tester strain of A. ostoyae. After pairing diploid field isolates with a haploid tester for 3 or 4 weeks, subcultures were taken from the haploid tester at 2 and 10 mm from the confrontation zone. Subcultures from 2 mm were mostly flat; subcultures from 10 mm were fluffy, flat, or fluffy with flat sectors. Hyphal tip cultures from the subcultures were analyzed for the isozyme markers. All fluffy hyphal tip cultures had the isozyme phenotype of the haploid tester. Flat hyphal tip cultures either had the isozyme phenotype of the diploid parent or had a hybrid isozyme phenotype with markers of both the diploid parent and the haploid tester. The data suggest that in conspecific diploid-haploid pairings, the diploid nucleus usually migrates into the haploid mycelium and eventually displaces the haploid nucleus.

Armillaria rhizomorphs consist of differentiated hyphae with a melanized outer cortex. Melanin is known to prevent lysis of fungal structures by hydrolytic enzymes and may protect against antagonistic microorganisms. Our studies indicate that melanized rhizomorphs also adsorb high concentrations of cations from the surrounding soil environment. Rhizomorphs of four Armillaria species (A. ostoyae (Romagn.) Herink, A. calvescens Bérubé & Dessureault, A. gemina Bérubé & Dessureault, and A. sinapina Bérubé & Dessureault) collected from Minnesota, New Hampshire, and Oregon had substantially elevated levels of metal ions compared with the soil from which they were collected. With some elements, ions were 50–100 times more concentrated on rhizomorphs than in soil. Concentrations of Al, Zn, Fe, Cu, and Pb on rhizomorphs ranged up to 3440, 1930, 1890, 15, and 680 μg/g, respectively. Energy dispersive X-ray microanalysis showed that metal ions were located only on the outer portions of the rhizomorphs and not concentrated in the interior. A coating of metal ions may play a key role in the longevity and survival of rhizomorphs in soil. Key words: Armillaria, rhizomorphs, metals, fungal antagonism.

Armillaria root disease (causal agent Armillaria mellea sensu stricto) is a major disease of fruit and nut crops in California, USA. An aspect of Armillaria root disease in orchard crops that has not been extensively studied is the spatial distribution of the fungus on the roots of mature trees and how this translates to symptom expression and yield loss. Root systems of Bartlett pear trees at two commercial orchards were excavated utilizing one of two methods: pressurized water or supersonic air. At both sites, trees were selected to represent a range of crown conditions (from declining to apparently healthy) in and around Armillaria infection centers. Root systems were excavated to a minimum diameter of 2 m and a minimum depth of 1 m. At both sites, numerous independent infections by Armillaria were observed on the roots of diseased trees. Discrete lesions were scattered on root surfaces, ranging in size from several square centimeters to large lesions covering hundreds of square centimeters. The root system excavations revealed a lack of root contact or root grafts between adjacent pear trees. Rhizomorphs were prevalent on root surfaces and in the soil at both sites. Both methods resulted in loss of very fine roots (

Two cases of Spigelian hernia are reported. Starting from the analysis of these cases, some observations about the anatomy, the etiology, clinic, diagnostic methods and the best therapeutic choices now available for this uncommon pathology are presented.

(1990). Notes on the Rhizomorphs and Mating System of Xeromphalina Campanella. Mycologia: Vol. 82, No. 5, pp. 651-655.

Crown dieback and mortality of red spruce and balsam fir in the subalpine zone of the northern Appalachian Mountains have been attributed to wind-induced crown and root damage. Vertical root movements, damage to roots and crowns, and growth rate were measured on wind-exposed spruce and fir trees near canopy gaps at Kancamagus Pass (875 m elevation) and Wildcat Mountain (1160 m) in the White Mountain National Forest, New Hampshire. Root movements were significantly correlated with windspeed, crown exposure, and depth of soil to rock. Woody roots that had made movements in excess of 10 mm had fewer small (1–3 mm diameter) roots, more abrasion wounds, and a greater amount of nonconducting (dry or discolored) xylem than roots that had made smaller movements. Hydraulic conductivity was significantly reduced in roots with greater than 40% xylem cross-sectional area that was nonconducting. Spruce and fir trees at gap margins grew slower and had more root and crown damage than trees sheltered within the canopy. Decreases in growth rate of spruce and fir trees at both sites during the past 20 years were significantly correlated with wind exposure and some of the root and crown damage variables.

Harrington, T. C., Worrall, J. J., and Rizzo, D. M. 1989. Compatibility among host-specialized isolates of Heterobasidion annosum from western North America. Phytopathology 79:290-296. Host-specialization of isolates of Heterobasidion annosum from from another 18 trees and stumps in Pacific Coast states also fell into the S California was previously demonstrated by inoculating Pinus ponderosa and P groups based on compatibility; those from diseased pine trees were and Abies concolor (white fir) seedlings in the greenhouse. In the present P-compatible and those from other host genera were S-compatible. study, 18 of these isolates were tested for sexual compatibility in hetero- However, compatibility of isolates and strains from stumps with S and P karyon-homokaryon pairings with six S and four P tester strains of H. testers was not consistent with the host genus, indicating that stump annosum from Europe representing two intersterility groups. colonization can be non-host specific. When North American strains were Compatibility was determined by the presence of clamp connections in paired among themselves or with heterokaryotic isolates, the two subcultures from the homokaryotic tester mycelia taken 5 wk after pairing, compatibility groups were less evident than when European strains were The nine isolates specialized to fir seedlings were compatible with S testers, used. Reports thus far suggest that both the S-compatible and Pand the nine isolates specialized to pine seedlings were compatible with P compatible groups are widespread in western North America, but only the testers. Some P-compatible isolates formed clamps with a few S testers. P group has been reported in eastern North America. Heterokaryotic isolates and homokaryotic (single-basidiospore) strains

An extensive study of the decay of the compound nuclei 58,60,62 Ni formed in the reactions ( 12 C + 46 Ti), ( 28 Si + 30 Si), ( 12 C + 48 Ti), ( 30 Si + 30 Si), ( 12 C + 50 Ti), ( 18 O + 44 Ca) was undertaken in the energy range ~ 0.7 to ~ 1.6 Coulomb barrier in about 20 steps. The fusion cross sections are fragmented in a large number of exit channels, with cross sections from 0.1 to 430 mb. By means of in-beam γ-ray measurements, the evaporation residues were identified both in A and Z . This large data base was compared with fusion-evaporation calculations through individual residue excitation functions and summed evaporation-residue cross sections (resulting from nucleons or α-emission). The model, with a standard set of parameters, does account for the general features of the experimental data, especially for the stronger exit channels. However, these data are not sensitive enough to the presence of other types of mechanisms and must be complemented by other observables to boost the predictive power of the model.