Influence of mycorrhizal preparation on seedling growth and Armillaria infestation

The influence of three types of treatment on seedling survival percentage, growth and Armillaria infestation of Fagus sylvatica L. (FAGUS), Abies alba Mill. (ABIES) and Picea abies (L.) H. Karst. (PICEA) seedlings were tested in this study: (i) inoculation with the Ectovit® preparation containing ectomycorrhizal fungi (INOCUL), (ii) Ectovit® preparation + Conavit® fertilizer (INOCUL + FERTILIZ) and (iii) the untreated group (CONTROL). The selected sample contained 100 seedlings per each tree species and treatment type (900 seedlings in total). Besides that, 18 months after planting, 10 living seedlings per each species and treatment (90 seedlings in total) were sampled to evaluate root dry mass and Armillaria infestation. The data were statistically evaluated by frequency analysis, analysis of variance and Kruskal-Wallis test. The overall seedling survival percentage was very low, probably due to extreme drought and high temperatures, with significantly lower results for the ABIES INOCUL + FERTILIZ and PICEA INOCUL + FERTILIZ groups. All tested growth characteristics (seedling height increment, root collar diameter increment, seedling shoot dry weight, root dry mass) were significantly higher in PICEA seedlings. Root collar diameter increment showed significant differences within each species and inconsistent results. Armillaria was detected only in the PICEA CONTROL group as rhizomorphs identified as A. ostoyae. The results suggest that the artificial mycorrhizal preparation can be an efficient method of preventing Armillaria infestation, especially in spruce seedlings.