Effect of temperature on the eradication of house longhorn beetle larvae in wood by microwave treatmentFranc Pohleven
, Martin Klinc
Povzetek: In repressive protection of cultural/historical woodwork, microwaves have many advantages over conventional heating. The research%s objective was to examine conditions for eradication of house longhorn beetle larvae (Hylotrupes bajulus) in spruce wood (Picea abies) using microwaves. Larvae, inserted at different depths of spruce blocks containing 12% and 42% of moisture, were exposed to microwaves. Two apparatuses were used; a 750W commercial microwave chamber and a newly developed horn antenna microwave device with the power of 800W and a frequency of 2.45GHz, for targeted radiation. We discovered that the inner part of wood warmed up quicker than the surface heated to 65°C. For successful suppression larvae in the wood need to be heated to 54.5°C, for 10 seconds. The necessary exposure time increases with increasing thickness of wood. The surface of wood containing more moisture is heated quicker, but increased moisture slows down the penetration of microwaves into the wood specimen. Therefore, larvae in wood of lower moisture (12%) died faster, both those 20mm under surface (1.5min) and those at 130 mm of depth (10.5min).
Ključne besede: wooden objects, repressive wood protection, microwaves, heating, wood moisture content, house longhorn beetle, Hylotrupes bajulus
DiRROS - Objavljeno: 25.10.2017; Ogledov: 1497; Prenosov: 449
Celotno besedilo (1,52 MB)
The effect of Eutypella parasitica on the wood decay of three maple speciesNikica Ogris
, Jožica Gričar
, Miha Humar
, Barbara Piškur
, Ana Brglez
Povzetek: Eutypella parasitica R.W. Davidson & R.C. Lorenz is the causative agent of Eutypella canker of maple, a destructive disease of maples in Europe and North America. The fungus E. parasitica is known to cause wood stain and decay. However, it is not known how effectively it decomposes the wood of the most widespread maple species in Europe. Wood samples of Acer pseudoplatanus L., A. platanoides L., and A. campestre L. were exposed to four isolates of E. parasitica and nine other fungal species for comparison, according to the modified EN 113 standard. After 15 weeks of incubation, mass loss and microscopical analysis of samples showed evidence of colonization and different wood decay potentials among fungal species. A highly significant positive correlation was found between mass loss and moisture content for all fungal species. Similarly, the measured cell wall thickness correlated well with the calculated mass loss of the samples. On average, the fungal species caused the lowest mass loss in A. pseudoplatanus (10.0%) and the highest in A. campestre (12.6%) samples. Among the samples exposed to E. parasitica isolates, the highest mass loss was recorded in A. pseudoplatanus (6.6%). Statistical analysis showed significant differences in mass loss and moisture content between different E. parasitica isolates. Based on the results of staining, we discuss the type of decay caused by E. parasitica. Although E. parasitica isolates caused smaller mass loss of samples compared to other more effective decay species, we should not disregard its capability of degrading maple wood. Because E. parasitica usually infects the lower portion of the trunk, which is the largest and most valuable part of the tree, any damage can cause significant economic and resource loss.
Ključne besede: wood decay, mass loss, moisture content, mini-block test, decay test, Acer spp., Eutypella parasitica, fungi, light microscopy, scanning electron microscopy
DiRROS - Objavljeno: 13.07.2020; Ogledov: 3; Prenosov: 1
Celotno besedilo (8,28 MB)
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