Breeding Increases the Efficacy of Chondrostereum purpureum in the Sprout Control of Birch

Abstract

We tested whether the pairing of selected isolates could be used to increase the efficiency of a decay fungus Chondrostereum purpureum (Pers. Ex Fr.) Pouzar to control hardwood sprouting in Finland. We paired C. purpureum strains efficient in sprout control or highly active in laccase production, and tested the efficacy of their progeny in spout control experiments. This procedure resulted in a strain with an efficacy superior to that of the parental strains. The mortality of birch (Betula pendula Roth. and B. pubescens Ehrh.) 1 cm in stump diameter was 78%, 56% and 9% for the best progeny, the best parental strain and the control, respectively. Mortality was only slightly higher for B. pendula than for B. pubescens but no significant differences were found between the number or maximum height of stump sprouts. Our results showed that cross breeding of this decay fungus is a good alternative in attempts to produce efficient biocontrol agents against hardwood sprouting.

The efficacy of Chondrostereum purpureum in sprout control of birch during mechanized pre-commercial thinning

“…Mortality means that a stump had no sprouts and was therefore considered dead. Silver (Betula pendula) and downy birches (B. pubescens) were not separated in the analyses since they have been shown to respond similarly in these treatments (Hamberg et al 2015). The data used in the analysis consisted of 1436 birch stumps in 2015 and 2017, but, in 2016, only 1371 stumps were found and measured.…”

“…The basal suspension of C. purpureum (provided by Verdera Ltd.) included the fungal strain R5 (Hamberg et al 2015) containing a minimum of 10 6 colony forming units (Gonzáles 1996). It was diluted with tap water just before the treatments in the field (dilutions 1:100, 1:200 or 1:400).…”

“…Inventories were carried out by measuring a systematic, regularly shaped grid of 15 circular sample plots (r = 1.0 m) per treatment (control and fungal treatments), except that, in stand 4.1, altogether 30 plots were measured for the control (cutting only). The distance between the plots was determined according to the area (0.3-0.7 ha) excluding a buffer zone of 10 m between the treatments and from trees of neighboring stands to avoid their immediate effects on sprouting (Hamberg et al 2015). Altogether, the data consisted of 480 sample plots, but some plots were not found during the study, and, therefore, the final data consisted of 470 sample plots: 116 for the C. purpureum dilution 1:100, 73 for 1:200, 102 for 1:400, and 179 for the control (Table 1).…”

“…Pouzar, as a biocontrol agent has been studied (e.g. Wall 1986;Gosselin et al 1999;Setliff 2002;Vartiamäki 2009;Hamberg et al 2015). This is an environmentally friendly alternative to chemical herbicides.…”

“…The use of C. purpureum has been promising in field tests even though there is variation in results due to timing of the treatment, the accuracy of the spreading mechanism, the basal area of the stump, and tree species (Wall 1986;Setliff 2002;Vartiamäki et al 2009;Roy et al 2010;Hamberg et al 2015Hamberg et al , 2017Hantula 2016, 2018). As a method, applying C. purpureum inoculum manually on cut surfaces is challenging due to the high number of stumps within regeneration areas.…”