Low Water Availability Increases Necrosis in Picea abies after Artificial Inoculation with Fungal Root Rot Pathogens Heterobasidion parviporum and Heterobasidion annosum

Eeva Terhonen,Kathrin Blumenstein,Gitta Langer,Johanna Bußkamp,David Rӑscuţoi

doi:10.3390/f10010055

Eeva Terhonen, Kathrin Blumenstein + Show 3 more

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https://doi.org/10.3390/f10010055

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Abstract

Research Highlights: Dedicated experiments to investigate how disturbances will affect Heterobasidion sp.—Norway spruce pathosystems are important, in order to develop different strategies to limit the spread of Heterobasidion annosum s.l. under the predicted climate change. Here, we report on a greenhouse experiment to evaluate the effects of water availability on the infection severity of Heterobasidion parviporum or Heterobasidion annosum, respectively, on Picea abies saplings. Background and Objectives: Changes in climatic conditions and intense logging will continue to promote H. annosum s.l. in conifer forests, increasing annual economic losses. Thus, our aim was to test if disease severity in Norway spruce was greater after infection with H. parviporum or H. annosum in low water availability conditions, compared to seedlings with high water availability. Materials and Methods: We performed inoculation studies of three-year-old saplings in a greenhouse. Saplings were treated as high (+) or low (−) water groups: High water group received double the water amount than the low water group. The necrosis observed after pathogen inoculation was measured and analyzed. Results: The seedling growth was negatively influenced in the lower water group. In addition, the water availability enhanced the necrosis length of H. parviporum in phloem and sapwood (vertical length) in the low water group. H. annosum benefited only in horizontal length in the phloem. Conclusions: Disturbances related to water availability, especially low water conditions, can have negative effects on the tree host and benefit the infection ability of the pathogens in the host.

Highlights

IntroductionKKaarrsstt..)),, ttooggeetthheerr wwiitthh SSccoottss ppiinnee ((PPiinnuuss ssyyllvveessttrriiss LL..)),, ffoorrmmss tthhee bbaassiiss ffoorr rraaww mmaatteerriiaallss ooff tthhee ffoorreesstt sseeccttoorr iinn EEuurrooppee,, ccoonnttrriibbuuttiinngg ttoo sseevveerraall bbiilllliioonn EEUURR nneett iinnccoommee aannnnuuaallllyy
Spore deposition is followed by rapid colonisation of the wood material
The necrosis length did not affect the growth of the saplings, but horizontal necrosis had a significant correlation with the sapling height measured at the start of the experiment (Figure 6)

Summary

Introduction

KKaarrsstt..)),, ttooggeetthheerr wwiitthh SSccoottss ppiinnee ((PPiinnuuss ssyyllvveessttrriiss LL..)),, ffoorrmmss tthhee bbaassiiss ffoorr rraaww mmaatteerriiaallss ooff tthhee ffoorreesstt sseeccttoorr iinn EEuurrooppee,, ccoonnttrriibbuuttiinngg ttoo sseevveerraall bbiilllliioonn EEUURR nneett iinnccoommee aannnnuuaallllyy. Primary infections by Heterobasidion species are established when airborne basidiospores land and germinate on freshly cut stump surfaces and wounds [10,11,12]. Silvicultural control of Heterobasidion species is difficult because they cause secondary infections by spreading through root contacts to neighbouring trees [18,19]. This is the main pathway for infections to spread inside stands [9,16,20]. Dedicated experiments to investigate how disturbances will affect the Heterobasidion sp.—Norway spruce pathosystems are important, in order to develop different strategies to limit the spread of H. annosum s.l. under the predicted climate change

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