Forest farming of shiitake mushrooms: aspects of forced fruiting.

Three outdoor shiitake (Lentinula edodes (Berk.) Pegler) cultivation experiments were established during 2002-2004 at the University of Missouri Horticulture and Agroforestry Research Center, in central Missouri. Over three complete years following a year of spawn run, we examined shiitake mushroom production in response to the temperature of forcing water, inoculum strain, substrate host species and physical orientation of the log during fruiting. Forcing compressed the period of most productive fruiting to the two years following spawn run. Further, chilled forcing water, 10-12 degrees C, significantly enhanced yield, particularly when ambient air temperatures were favorable for the selected mushroom strain. The temperature of water available for force-fruiting shiitake logs depends on geographic location (latitude) and source (i.e., farm pond vs. spring or well water). Prospective growers should be aware of this effect when designing their management and business plans.

Forest farming of shiitake mushrooms: an integrated evaluation of management practices.

Two outdoor shiitake (Lentinula edodes) cultivation experiments, established in Missouri USA in 1999 and 2000, produced mushrooms in 2000-2005. We examined shiitake production in response to substrate species, inoculum form, inoculum strain, and inoculation timing, using total mushroom weight per log as the primary response variable with log characteristics as covariates. The significantly greater mushroom weight produced by sugar maple logs compared with white or northern red oak was attributable to the higher proportion of undiscolored wood volume in the maple logs, rather than to bark thickness or log diameter. The "wide temperature range" shiitake strain produced significantly greater yield compared with the "warm" or "cold" weather strains. Both the wide-range and warm-weather strains were stimulated to fruit by significant rain events, while the cold-weather strain was responsive to temperature. Inoculation with sawdust spawn gave significantly greater yield than colonized wooden dowels or pre-packaged "thimble" plug inoculum. The second and third full years following inoculation were the most productive.

Seedling disease in an annual legume: consequences for seedling mortality, plant size, and population seed production.

The effect of seed and seedling mortality on plant population dynamics depends on the degree to which the growth and reproduction of surviving individuals can compensate for the deaths that occur. To explore this issue, we sowed seeds of the annual Kummerowia stipulacea at three densities in sunken pots in the field, which contained either field soil, microwaved field soil, or microwaved field soil augmented with oospores of three Pythium species. High sowing density reduced seedling establishment and seedling size, but these effects were independent of the soil treatment. In the oospore-augmented soil, seed and seedling survival was low. The surviving plants were initially smaller but, at maturity, average plant size was greatest in the oospore-augmented soil, compared to the other treatments. Total population seed production was unaffected by soil treatment, suggesting that the effect of disease was limited to the seedling stage, with surviving plants released from intraspecific competition. To test the hypothesis that the surviving plants in the oospore-augmented soil were more disease-resistant, seeds from each of the sowing density-soil type treatments were sown in a growth chamber inoculation study. No evidence for selection for resistance was found. A second inoculation experiment revealed that oospore inoculum reduced plant numbers and mass regardless of whether field or microwaved soil was used, suggesting that results from the field experiment were not dependent on the use of microwaved soil. The findings of this study indicate that the ecological effects of disease on individual plants and on plant populations are not necessarily equivalent.

Changes in Heterodera glycines Egg Population Density in Continuous Glycine max over Four Years.

Soybean cyst nematode, Heterodera glycines, is found throughout soybean production areas of the United States, but the nematode's distribution is not uniform within states, counties, and individual fields. The goal of this research was to determine the spatial pattern of H. glycines population density in a field in southeastern Missouri and whether it changed over time in the absence of management practices. Geostatistical methods were used to describe and map the distribution of H. glycines over 4 years in a soybean (Glycine max) field in southeastern Missouri. Semivariograms and kriging, an interpolation method, were used to prepare isoarithmic contour maps and associated error maps. In the field studied, fall H. glycines population density (Pf) was poorly related to density the following spring (Pi). The distribution of peak H. glycines population density within the field changed from year to year, although high densities were often detected in the same general region of the field. The patchiness of H. glycines distribution within a field was verified. Yield was not related to H. glycines egg population density at planting, indicating that unmeasured variables were also reducing yield.

Episodic Dynamics of Tar Spot of Annual Lespedeza Within and Among Years.

The temporal and spatial dynamics of six tar spot epidemics were examined at two sites in mid-Missouri during 1990 to 1992. The sites, 48 km apart, differed in topography (flat versus slope), soil texture (silt loam versus silty-clay loam), and cropping history (orchard versus row crops). Temporal dynamics of disease incidence differed more among years than between sites. During 1990, temporal dynamics of the two epidemics followed a classic monotonic increase, whereas disease increase was episodic for the four epidemics observed during 1991 and 1992. Disease increase was associated with shading of the plant canopy or with the presence of dodder. Disease increase was related inversely to intercepted photosynthetically active radiation. Taken together, these observations suggest that factors that increase shading in the lespedeza canopy also increase tar spot incidence. For only two of the six epidemics was there a significant relationship between disease incidence (proportion of leaflets diseased) and disease severity (proportion of leaflet area diseased), with disease severity rarely exceeding 10%. These observations suggest that relatively low tar spot incidence may result in significant leaf losses, which would reduce lespedeza hay quality and yield. Further, this study demonstrates the importance of experimental repetition in both space and time to fully appreciate the range of disease dynamics for a single pathosystem.