Michael P. Amaranthus

Rapid root tip and mycorrhiza formation and increased survival of Douglas-fir seedlings after soil transfer

In order to re-inoculate soil with mycorrhizal fungi, small amounts (about 150 ml) of soil from an established Douglas-fir plantation were added to planting holes when Douglas-fir seedlings were planted on an old, unrevegetated clearcut in the Klamath Mountains of Oregon. Seedlings were lifted throughout the growing season to determine the influence of soil transfer on the rate of root tip initiation and mycorrhiza formation. Six weeks after planting, seedlings receiving plantation soil had formed 62% more root tips than controls; however, no statistically significant differences were apparent 15 weeks after planting. By that time, a small percentage of root tips were visibly mycorrhizal; seedlings receiving transferred soil had the most colonization (13.6 vs 3.5 per seedling, p ≤0.05). Of seedlings receiving transfer soil, 36.6% survived the first growing season, compared to 11.3% of control seedlings. At this high elevation, soils often remain frozen well into spring, leaving only a brief period betwen the time when soils become warm enough for root growth and the onset of summer drought. Under these conditions, the rapid root growth and mycorrhiza formation stimulated by plantation soil increases the ability of seedlings to survive the first growing season.

Productivity and Sustainable Harvest of Edible Forest Mushrooms

Summary The commercial harvest of wild edible forest mushrooms has increased dramatically in the Pacific Northwest United States during the last decade, creating public and managerial concerns about potential over-harvesting. These concerns have prompted Federal land m anagement agencies and research organizations to undertake a variety of research projects addressing the ecological impacts and long-term sustainability of widespread harvesting. This article lists and briefly describes 25 ongoing research projects investigating the three most important forest mushroom genera of commerce; matsutake, morels, and chanterelles. We finish by describing future Federal directions in regional research and monitoring designed to ensure sustainable harvests through long-term cooperative monitoring involving multiple stakeholders, especially interested publics.

Improved Rhizopogon Mycorrhizal Colonization and Foliar Nutrient Levels in Ponderosa Pine and Douglas-Fir with Myconate(r)

Abstract The importance of mycorrhizal colonization in the establishment and growth of forest trees has long been recognized, and mycorrhizal inoculum is used regularly in replanting. The isoflavonoid formononetin (7-hydroxy-4′-methoxy isoflavone), sold as Myconate(r), has been shown to increase colonization by endo- but not ectomycorrhizae. The purpose of this study was to test the ability of Myconate(r) to increase colonization, nutrient uptake, and growth in ponderosa pine and Douglas-fir seedlings inoculated with Rhizopogon ectomycorrhizae spores. In these tests Myconate(r) significantly increased root colonization by Rhizopogon in both tree species at 60 mg/L. In Douglas-fir seedlings, potassium content was significantly higher in seedlings treated with 60 mg/L of Myconate(r) and Rhizopogon parksii than in either the untreated plants, or those treated with R. parksii alone. Treatment with R. parksii and Myconate(r) significantly increased Douglas-fir phosphorus and nitrogen content over the untreated control, but not over the treatment with R. parksii alone. In ponderosa pine seedlings, Myconate(r) treatment at 60 mg/L significantly increased nitrogen, but not phosphorus or potassium content over seedlings treated with R. rubescens alone. Caliper diameter of ponderosa pine was not significantly increased with the application of Myconate(r), while in Douglas-fir, both R. parksii and R. parksii plus Myconate(r) treatments increased caliper size over the control.

Fraxinus americana Roots Respond to Subsurface Feeding of Mycorrhizal Inoculum and Nitrogen Fertilizer

Abstract Ball and burlap Fraxinus americana (Autumn purple ash) trees were evaluated for their response to subsurface feeding of mycorrhizal inoculum with root biostimulant (mycorrhiza Roots) and nitrogen fertilizer (Coron 28-0-0) on difficult sites in the Colorado front range. Two root ingrowth cores were installed around each of twelve trees following planting in fall 1998 and excavated in fall 1999. Inoculation with mycorrhiza Roots alone resulted in sigificantly increased dry root weights and mycorrhizal colonization percentage on treated purple ash trees (p ≤ 0.05). Mycorrhiza Roots with Coron also significantly increased dry root weights and mycorrhizal colonization percentage on treated ash (p ≤ 0.05). Increases in root growth were dramatic. Purple ash trees treated with mycorrhiza Roots and Coron had greater than 3.5 times the dry root weights in excavated root ingrowth cores compared controls. Trees treated with mycorrhiza Roots alone had greater than 3 times the dry weights compared to controls. Trees treated with mycorrhiza Roots alone had more than 12 times higher mycorrhi-zal colonization percentage compared to controls. Control trees were poorly colonized by mycorrhizal fungi. This study indicates that subsurface feeding of purple ash ball and burlap trees following outplanting with mycorrhizal inoculum and root biostimulant can greatly improve root growth and mycorrhizal colonization.