Urea treatment reduced Heterobasidion annosum s.l. root rot in Picea abies after 15 years

2008 ◽  
Vol 255 (7) ◽  
pp. 2876-2882 ◽  
Author(s):  
J. Oliva ◽  
N. Samils ◽  
U. Johansson ◽  
M. Bendz-Hellgren ◽  
J. Stenlid
2001 ◽  
Vol 31 (6) ◽  
pp. 937-942 ◽  
Author(s):  
Tuula Piri ◽  
Kari Korhonen

The incidence of Heterobasidion root rot in the advance regeneration of Norway spruce (Picea abies (L.) Karst.) was studied in nine stands at four different localities in southern Finland. The mean age of the unthinned advance regeneration on the 17 sample plots ranged from 14 to 44 years. On infested plots, the proportion of Norway spruce infected by Heterobasidion varied from 22.2 to 75.0% (mean 52.5%) in the overstory and from 1.8 to 68.2% (mean 21.1%) in the advance regeneration. The corresponding values on healthy-looking control plots were 0–6.7% (mean 5.9%) and 1.3–3.9% (mean 2.4%), respectively. Of the 138 Heterobasidion genets identified, 98.5% belonged to Heterobasidion parviporum Niemelä & Korhonen and 1.5% to Heterobasidion annosum (Fr.) Bref. s.s. The incidence of Heterobasidion root rot in advance regeneration was positively correlated with the mean size and age of the advance regeneration and the proportion of infected trees in the overstory and negatively correlated with the regeneration density. Vegetative spread through root contacts from overstory trees to the surrounding regeneration accounted for at least 53% of the Heterobasidion infections in the advance regeneration. The origin of the rest of the infections in advance regeneration remained unclear, but at least part of them may have started from spore infection on injured or dead roots. Our results suggest that, on sites infected by H. parviporum, advance growth of Norway spruce should not be used for regeneration even though the spruces look healthy and show no external signs of infection.


2003 ◽  
Vol 33 (4) ◽  
pp. 604-611 ◽  
Author(s):  
Tuula Piri

Root rot infections in Norway spruce (Picea abies (L.) Karst.) regeneration, planted after the clear-cutting of spruce on sites infested by Heterobasidion, were investigated on 21 experimental plots in eight 2- to 23-year-old plantations. Heterobasidion root rot became evident about 10 years after planting and the proportion of infected spruces increased steadily with plantation age. The average number of planted spruces infected per old decayed stump was 0.2 trees in 2- to 9-year-old plantations, 0.8 trees in 11- to 15-year-old plantations, and 1.8 trees in 20- to 23-year-old plantations. About 10 and 20 years after planting, 7 and 23% of the planted spruces in the disease centers were infected by Heterobasidion. Heterobasidion parviporum Niemelä & Korhonen, and Heterobasidion annosum (Fr.) Bref. s. str. caused 98 and 2% of the Heterobasidion infections in the previous spruce rotation, and 96 and 4% in the spruce regeneration, respectively. In all, 71% of the infected regeneration trees were attacked by a Heterobasidion genet that was also isolated from the stumps of the previous tree stand. Armillaria species (Armillaria borealis Marxmüller & Korhonen and Armillaria cepistipes Velenovský) were isolated from 7% of the planted spruces.


2004 ◽  
Vol 34 (1) ◽  
pp. 120-130 ◽  
Author(s):  
Vaidotas Lygis ◽  
Rimvydas Vasiliauskas ◽  
Jan Stenlid

Persistence of the root rot pathogen Heterobasidion annosum (Fr.) Bref. s.s. on infested areas and its transfer to a forest regeneration was studied in three forest sites in eastern Lithuania. The sites represented H. annosum disease centres in Pinus sylvestris L. stands, which were clear-felled and replanted with Betula pendula Roth 25 years prior to our study. Fungal isolation from trees and stumps on each site was performed on both replanted B. pendula and surrounding P. sylvestris from the previous generation. Low productivity of B. pendula stands (45.0–76.1 m3·ha–1), high mortality rates, and comparatively low vigor of trees (measured as crown densities) indicated a strong impact of root rot. Based on somatic incompatibility tests, we detected large spreading areas of clones of H. annosum (up to 48 m across) and old (35- to 40-year-old) clonal individuals. Territorial clones covered areas that encompassed both previous stands of P. sylvestris and current stands of B. pendula. Our results showed that H. annosum is able to persist in root systems of diseased trees for decades and readily attack birch replanted on infested sites. In addition, a total of 83 fungal species (out of 398 isolates) was found as a result of sampling 508 B. pendula, 49 P. sylvestris, 21 Juniperus communis L., and 1 Salix cinerea L. trees.


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