HuskStihl
Chairin'em for the sound
The kids these days.......
Hey Madhatte....
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Thing is, we don't have a lot of spruce here, and a lot of it is affected by the weevil, and alder grows on similar soils, so this could well be a help.
OlympicYJ
ArboristSite Guru
Nate: here is the paper I wrote. Much easier than typing it all up and no memory lapses. Which I had one; the paper was about spruce tip weevil and alder was one of the management tools, in red.
Sitka spruce (Picea sitchensis (Bong.) Carr) historically has been a culturally, economically and biologically important tree species in the Pacific Northwest. Sitka Spruce’s native range spans the Pacific coast from Southeast Alaska to Northern California. Just like any other timber species, Sitka spruce has been naturally and artificially regenerated. Unfortunately Sitka spruce suffers from predation by the Sitka spruce weevil, Pissodes strobi (Peck) (Coleoptera: Curculionidae). Predation by the weevil has caused regeneration of Sitka spruce to be avoided (Alfaro and King 2012; Almond 2006; King et al. 2012; Mitchell et al. 1990). Avoidance is not a viable option for the continued production of Sitka spruce as a timber crop thus emphasizing the need for an integrated pest management solution (Almond 2006).
Sitka spruce weevil, also known as white pine weevil and Engelmann spruce weevil are genetically the same weevil, Pissodes strobi (Peck) (Coleoptera: Curculionidae), and is found throughout North America (Hamid et al. 1995; King et al. 2012). Sitka spruce is most susceptible to Spruce weevil attack between 7 and 25 years of age (Almond 2006). Adults overwinter on the forest floor in the duff layer or on the foliage. Upon emergence Sitka spruce weevils walk to a host and oviposit just below the terminal bud of the leader (Hamid et al. 1995; Mitchell et al. 1990, VanderSar and Borden 1977). When seeking out a host both male and females visually look for vertical to near vertical leader silhouettes of around 3 cm (VanderSar and Borden 1977). Larvae hatch and bore into the leader eventually severely deforming or killing it; this causes the formation of multiple leaders, the visual characteristic of weevil damage (Alfaro and King 2012; Mitchell et al. 1990; VanderSar and Borden 1977). Previously attacked trees are more susceptible to re-attack (VanderSar and Borden 1977). The stunting of growth and usually accompanied re-attacks result in the creation of short stunted trees.
Red alder has the potential to be used as a silvicultural technique as part of integrated pest management to prevent Sitka spruce weevil success. Sitka spruce weevils tend to oviposit between 77°F and 84°F with 20% to 35% humidity (Almond 2006). The red alder overstory modifies the microclimate underneath the canopy to levels that either prevents oviposition or reduces larval survival (Almond 2006; Hamid et al. 1995). However using red alder comes with a downside; whiplash of the Sitka Spruce can occur slowing growth and causing multi leaders to occur. A red alder canopy density of approximately 88% will reduce whiplash while still providing sufficient microclimate. A Sitka spruce to red alder ratio of 1:3 provides the best protection but only able to occupy up to 25% of the stand density; the higher red alder density also has the effect of creating more upright branching reducing whiplash (Almond 2006). As evidenced this management strategy can be quite difficult to execute due to the inexact nature of this prescription and site difficulties in establishing red alder.
Instead of trying to control the microclimate of stands research has been done on breeding for genetic resistance and hybridization. Canadians in cooperation with the United States started a resistance breeding program in the early 1990s utilizing native populations expressing resistance to weevils. This program has been hugely successful resulting in seedlings that express total resistance and now provides the majority of the weevil resistant seedstock. (King et al. 2012) In 1958 an experiment was undertaken to examine weevil damage and growth of 10 spruce species and hybrids on sites located in Washington and Oregon. The study found that a Sitka spruce x white spruce cross was 100% weevil resistant but resulted in slowed growth (Mitchell et al. 1990).
The future is looking bright for commercially growing Sitka spruce that is weevil resistant. While much of the research is old, and scarce for that matter, there is a lot of industry, government, and cross country cooperation on finding a solution to Sitka spruce weevil. I have seen the damage from the weevil first hand and can attest to how staggeringly destructive it can be. Due to red alder overstory being a very difficult management tool and the development of totally resistant seedlings I would imagine Sitka spruce management will focus on pure plantations of Sitka spruce derived from the resistant seedlings from British Columbia. It is interesting how the research I found has not brought up climate change as a potential driver or aid behind the outbreak. Either the research was narrowly focused on purpose or climate change was overlooked as a possible driver. While Sitka spruce is probably the least valuable conifer on the coast it is still an important timber species for the export and railroad tie markets. If it were to be wiped out increased pressure would be put on other more expensive timber trees to fill the void; not to mention the ecological role that Sitka spruce fulfills in riparian areas and the loss diversity.
References
Alfaro, R.I., King, J.N. 2012. Screening Sitka spruce for resistance to weevil damage in British Columbia. USDA For. Serv. Gen. Tech. Rep. PSW-GTR-240.
Almond, L. 2006. The value of Red Alder as an integrated pest management tool for controlling weevil damage to Sitka spruce. USDA For. Serv. Gen. Tech. Rep. PNW-GTR-669.
Hamid, A., O'Dell, T.M., Katovich, S. 1995. White pine weevil. USDA For. Serv. For. Ins. Dis. Leaf. Northern Area State & Private Forestry. FIDL. 21.
King, J.N., Alfaro, R.I., Ott, P., vanAkker, L. 2012. Phenotypic evidence suggests a possible major-gene element to weevil resistance in Sitka spruce. USDA For. Serv. Gen. Tech. Rep. PSW-GTR-240.
Mitchell, R.G., Wright, K.H., Johnson, N.E. 1990. Damage by the Sitka spruce weevil (Pissodes strobi) and growth patterns for 10 spruce species and hybrids over 26 years in the Pacific Northwest. USDA For. Serv. Res. Pap. PNW-RP-434.
VanderSar, T.J.D., and Borden, J.H. 1977. Visual orientation of Pissodes strobi Peck
(Coleoptera: Curculionidae) in relation to host selection behaviour. Can. J. Zool. 55(12): 2042-2049. doi: 10.1139/z77-265
Sitka spruce (Picea sitchensis (Bong.) Carr) historically has been a culturally, economically and biologically important tree species in the Pacific Northwest. Sitka Spruce’s native range spans the Pacific coast from Southeast Alaska to Northern California. Just like any other timber species, Sitka spruce has been naturally and artificially regenerated. Unfortunately Sitka spruce suffers from predation by the Sitka spruce weevil, Pissodes strobi (Peck) (Coleoptera: Curculionidae). Predation by the weevil has caused regeneration of Sitka spruce to be avoided (Alfaro and King 2012; Almond 2006; King et al. 2012; Mitchell et al. 1990). Avoidance is not a viable option for the continued production of Sitka spruce as a timber crop thus emphasizing the need for an integrated pest management solution (Almond 2006).
Sitka spruce weevil, also known as white pine weevil and Engelmann spruce weevil are genetically the same weevil, Pissodes strobi (Peck) (Coleoptera: Curculionidae), and is found throughout North America (Hamid et al. 1995; King et al. 2012). Sitka spruce is most susceptible to Spruce weevil attack between 7 and 25 years of age (Almond 2006). Adults overwinter on the forest floor in the duff layer or on the foliage. Upon emergence Sitka spruce weevils walk to a host and oviposit just below the terminal bud of the leader (Hamid et al. 1995; Mitchell et al. 1990, VanderSar and Borden 1977). When seeking out a host both male and females visually look for vertical to near vertical leader silhouettes of around 3 cm (VanderSar and Borden 1977). Larvae hatch and bore into the leader eventually severely deforming or killing it; this causes the formation of multiple leaders, the visual characteristic of weevil damage (Alfaro and King 2012; Mitchell et al. 1990; VanderSar and Borden 1977). Previously attacked trees are more susceptible to re-attack (VanderSar and Borden 1977). The stunting of growth and usually accompanied re-attacks result in the creation of short stunted trees.
Red alder has the potential to be used as a silvicultural technique as part of integrated pest management to prevent Sitka spruce weevil success. Sitka spruce weevils tend to oviposit between 77°F and 84°F with 20% to 35% humidity (Almond 2006). The red alder overstory modifies the microclimate underneath the canopy to levels that either prevents oviposition or reduces larval survival (Almond 2006; Hamid et al. 1995). However using red alder comes with a downside; whiplash of the Sitka Spruce can occur slowing growth and causing multi leaders to occur. A red alder canopy density of approximately 88% will reduce whiplash while still providing sufficient microclimate. A Sitka spruce to red alder ratio of 1:3 provides the best protection but only able to occupy up to 25% of the stand density; the higher red alder density also has the effect of creating more upright branching reducing whiplash (Almond 2006). As evidenced this management strategy can be quite difficult to execute due to the inexact nature of this prescription and site difficulties in establishing red alder.
Instead of trying to control the microclimate of stands research has been done on breeding for genetic resistance and hybridization. Canadians in cooperation with the United States started a resistance breeding program in the early 1990s utilizing native populations expressing resistance to weevils. This program has been hugely successful resulting in seedlings that express total resistance and now provides the majority of the weevil resistant seedstock. (King et al. 2012) In 1958 an experiment was undertaken to examine weevil damage and growth of 10 spruce species and hybrids on sites located in Washington and Oregon. The study found that a Sitka spruce x white spruce cross was 100% weevil resistant but resulted in slowed growth (Mitchell et al. 1990).
The future is looking bright for commercially growing Sitka spruce that is weevil resistant. While much of the research is old, and scarce for that matter, there is a lot of industry, government, and cross country cooperation on finding a solution to Sitka spruce weevil. I have seen the damage from the weevil first hand and can attest to how staggeringly destructive it can be. Due to red alder overstory being a very difficult management tool and the development of totally resistant seedlings I would imagine Sitka spruce management will focus on pure plantations of Sitka spruce derived from the resistant seedlings from British Columbia. It is interesting how the research I found has not brought up climate change as a potential driver or aid behind the outbreak. Either the research was narrowly focused on purpose or climate change was overlooked as a possible driver. While Sitka spruce is probably the least valuable conifer on the coast it is still an important timber species for the export and railroad tie markets. If it were to be wiped out increased pressure would be put on other more expensive timber trees to fill the void; not to mention the ecological role that Sitka spruce fulfills in riparian areas and the loss diversity.
References
Alfaro, R.I., King, J.N. 2012. Screening Sitka spruce for resistance to weevil damage in British Columbia. USDA For. Serv. Gen. Tech. Rep. PSW-GTR-240.
Almond, L. 2006. The value of Red Alder as an integrated pest management tool for controlling weevil damage to Sitka spruce. USDA For. Serv. Gen. Tech. Rep. PNW-GTR-669.
Hamid, A., O'Dell, T.M., Katovich, S. 1995. White pine weevil. USDA For. Serv. For. Ins. Dis. Leaf. Northern Area State & Private Forestry. FIDL. 21.
King, J.N., Alfaro, R.I., Ott, P., vanAkker, L. 2012. Phenotypic evidence suggests a possible major-gene element to weevil resistance in Sitka spruce. USDA For. Serv. Gen. Tech. Rep. PSW-GTR-240.
Mitchell, R.G., Wright, K.H., Johnson, N.E. 1990. Damage by the Sitka spruce weevil (Pissodes strobi) and growth patterns for 10 spruce species and hybrids over 26 years in the Pacific Northwest. USDA For. Serv. Res. Pap. PNW-RP-434.
VanderSar, T.J.D., and Borden, J.H. 1977. Visual orientation of Pissodes strobi Peck
(Coleoptera: Curculionidae) in relation to host selection behaviour. Can. J. Zool. 55(12): 2042-2049. doi: 10.1139/z77-265
Oh snap! That's solid gold. Turns out we're planting about 40 acres this next spring in alder and spruce and I'm not sure we've got the numbers hammered down; I may be able to get the chance to see this work. I'll give you full credit if it does! Thanks! I'm well familiar with the strategy of way overplanting and then thinning alder in order to build up Frankia nodules; this is just an elaboration on that which looks forward in time a generation past the alder and into the spruce as succession progresses.
OlympicYJ
ArboristSite Guru
I think it can work. Lyle Almond is really the expert on that as his work is about the only one on that. I would try getting ahold of him I would offer to track down his number but as of this evening I have a bunch of personal stuff I am dealing with at the moment that's going to keep me occupied for at least the rest of the week. Try Todd Bates at Grays Harbor College. He had Lyle present to the ecology class on a field trip up the Peninsula.
Will do, I have Todd's contact info from a work study program we did with one of his students a couple of years ago who was on my summer crew. Thanks for the tip!
