Figure 1:
Sampling and extraction of the pinewood nematode (Bursaphelenchus xylophilus (Steiner & Buhrer, 1934) Nickle, 1971) from whole pine (Pinus spp.) logs. A) Thirty yellow pine (Pinus spp.) logs laid out in the woodlot and numbered, ready to be sampled for pinewood nematodes. B) Hole drilled in an area without bark with a 2.5 cm diameter Forstner drill-bit 2.5 cm in depth with chips collected and placed in a quart-size plastic bag (C) and kept on ice while in the field. C,D) Ten grams of wood chips were placed on a single sheet of facial tissue paper on a Baerman funnel filled with water and covered with the tissue. E,F) After 12–16 hours, 5ml of water was drained from the plastic tube and examined for nematodes with a dissecting microscope. G) Pinewood nematodes were tentatively identified by overall body shape and characteristic movement.
Figure 2:
A) Whole yellow pine (Pinus spp.) logs were debarked at the woodlot and shipped to the research lab at Virginia Tech, where they were cut into 2.3 m lengths, and groups of four were placed on wooden pallets and randomly selected for the various treatments. B–D) The vacuum treatment set-up used in this research was custom-built inside a mobile trailer with a vacuum container, and the steam generator was used as the test chamber with the capacity to treat 4 whole 2.3 m logs at the same time. Temperature sensors were attached to the log at the same time at various sites on the log and inside the chamber.
Table 1:
The experimental design with schedules of treatments for the eradication of pinewood nematodes, (Bursaphelenchus xylophilus (Steiner and Buhrer, 1934) Nickle, 1971), in naturally infested whole pine (Pinus spp.) logs.
| Species | Treating schedule | Temperature target location | Number of logs/tests | Number of tests | Total number of logs |
|---|---|---|---|---|---|
| Pine | 48°C/15min. | Center | 4 | 3 | 12 |
| Pine | 56°C/30min. | Center | 4 | 3 | 12 |
| Pine | 60°C/60min. | Center | 4 | 3 | 12 |
| Control | 4 | 4 |
Table 2:
Testing dates, times, temperatures, and energy usage for the treatment of naturally infested whole pine (Pinus spp.) logs with pinewood nematodes (Bursaphelenchus xylophilus (Steiner and Buhrer, 1934) Nickle, 1971).
| Test | Date | Outside temp. | Vacuum time | Steam time | Holding time | Total time | Energy usage |
|---|---|---|---|---|---|---|---|
| 2021 | °C | min | min | °C/min | min | kwh | |
| Pine | |||||||
| 1 | Aug. 26 | 21 | 10 | 391 | 48/15 | 416 | 49.7 |
| 2 | Aug. 30 | 22 | 9 | 464 | 48/15 | 488 | 58.4 |
| 3 | Aug. 31 | 25 | 10 | 522 | 56/30 | 562 | 62.0 |
| 4 | Sept. 1 | 22 | 11 | 311 | 60/60 | 382 | 41.5 |
| 5 | Sept. 2 | 18 | 11 | 634 | 56/30 | 675 | 84.7 |
| 6 | Sept. 3 | 16 | 10 | 598 | 60/60 | 668 | 74.2 |
| 7 | Sept. 7 | 15 | 9 | 532 | 60/60 | 601 | 70.0 |
| 8 | Sept. 8 | 21 | 9 | 511 | 56/30 | 550 | 62.7 |
| 9 | Sept. 9 | 10 | 10 | 458 | 48/15 | 483 | 70.6 |
Figure 3:
Diagram of the sampling pattern for whole logs includes two sections to serve as controls to determine the presence of pinewood nematodes (Bursaphelenchus xylophilus (Steiner & Buhrer, 1934) Nickle, 1971) before treatment and 10 additional sites for sampling after treatment, including 5 near the surface and 5 at the center of the log. Each sample was obtained by drilling a 2.5 cm hole with a 2.5 cm diameter Forstner drill bit. The wood chips from each hole were placed in a plastic bag and stored in a cooler over ice until they were further processed.
Figure 4:
A) Line graph of temperatures at various levels in and on logs and within the chamber during the treatment of 60°C for 60 min. B) Line graph of temperatures at various levels in and on logs and within the chamber during the treatment of 48°C for 15.
Table 3:
Means and standard deviations of pinewood nematodes (Bursaphelenchus xylophilus (Steiner and Buhrer, 1934) Nickle, 1971) counts per gram of wood shavings from two depths and three treatments of naturally infested whole pine (Pinus spp.) logs.
Table 4:
Numbers of failures for each treatment on the surface and in the center of naturally infested whole pine (Pinus spp.) logs for the eradication of pinewood nematodes, (Bursaphelenchus xylophilus (Steiner and Buhrer, 1934) Nickle, 1971).
| Treatment | Sample location | Number | Failures | Percent failure |
|---|---|---|---|---|
| 48°C/15min | Surface | 60 | 22 | 36.7 |
| 48°C/15min | Center | 60 | 24 | 40.0 |
| 48°C/15min | Total | 120 | 46 | 38.3 |
| 56°C/30min | Surface | 60 | 8 | 13.3 |
| 56°C/30min | Center | 60 | 33 | 55.0 |
| 56°C/30min | Total | 120 | 41 | 34.2 |
| 60°C/60min | Surface | 60 | 9 | 15.0 |
| 60°C/60min | Center | 60 | 4 | 6.7 |
| 60°C/60min | Total | 120 | 13 | 10.8 |
| Total | Surface | 180 | 39 | 21.7 |
| Total | Center | 180 | 61 | 33.9 |
| Total | Total | 360 | 100 | 27.8 |
| Control | Surface | 20 | 0 | 0.0 |
| Control | Center | 20 | 1* | 5.0 |
| Total | Total | 40 | 1* | 2.5 |
Table 5:
Percent increase pinewood nematode (Bursaphelenchus xylophilus (Steiner and Buhrer, 1934) Nickle, 1971) populations in naturally infested whole pine (Pinus spp.) logs from the 60°C/60 min treatment 1 month after treatment from the surface and center sampling locations.
| Sample | Initial | 1 month later | Percent increase |
|---|---|---|---|
| Surface | 0.14 | 17.1 | 12,214% |
| Center | 0.27 | 5.5 | 2,037% |
| Total | 0.21 | 11.3 | 5,381% |
Table 6:
Means of pinewood nematodes (Bursaphelenchus xylophilus (Steiner and Buhrer, 1934) Nickle, 1971) counts per gram of wood shavings from treated naturally infested whole pine (Pinus spp.) logs one year after treatment.