We have completed the 2004 Southern Pine Beetle (SPB) pheromone trapping. The results of this survey are attached. Insect development in ice damaged pines and the potential for losses there are discussed also.
A total of 31 S.C. counties were trapped for SPB in 2004 using protocol devised by Billings, et al. This protocol includes monitoring 3 pheromone traps in each county for a 28-day period during early spring. Insects captured in each trap are returned to the laboratory for analysis. The total number of SPB for each trap is determined as well as the percentage of SPB to clerid beetles. Since clerid beetles are major predators of SPB, the percentage of them trapped is factored into insect population projections. Based on this trapping, a population prediction trend is determined for each county. In the past, such surveys have had a success rate of over 80% in predicting the degree of SPB infestation during the following summer. The last year we had a significant miss in our predictions was in 1996. Last year’s survey correctly predicted the SPB population levels in 25 of 31 counties.
Of the counties trapped this year, none are predicted to experience a severe southern pine beetle outbreak. This is a considerable change from 2002 when 18 counties were predicted to experience a severe outbreak. Additionally, no counties trapped sufficient beetles in all traps to receive a prediction of increasing - high pine mortality. In Dorchester, Edgefield, Horry, McCormick and Saluda counties we can expect losses similar to those recorded in 2003. The other 26 counties we sampled had few beetles trapped and are not expected to have widespread problems. These counties include Abbeville, Anderson, Beaufort, Berkeley, Charleston, Cherokee, Chester, Colleton, Fairfield, Georgetown, Greenville, Greenwood, Hampton, Jasper, Kershaw, Lancaster, Laurens, Lexington, Newberry, Oconee, Pickens, Richland, Spartanburg, Union, Williamsburg and York. However, there were several individual traps in counties with an overall low prediction that caught significant numbers of beetles. Because of this, we can expect sporadic SPB activity in some of the low rated counties. This trapping information is presented in tabular and graphical form later in this report.
Statewide, the number of SPB trapped declined to about 50% of last year’s totals and the number of clerids caught nearly doubled. This high clerid population should constrain explosive SPB development in most areas of the piedmont, but probably will be insufficient to prevent all losses. Since the SPB killed $6.5 million of pines in S.C. last year, we can expect losses in the range of $5 - $10 million during 2004. As usual, a hot summer with extended temperatures over 100 degrees could inhibit beetle population development.
In the coastal plains, the clerid/ SPB ratio is less favorable and again this year some southern pine beetles were trapped in every trap we deployed. Due to the explosive nature of the SPB, a potential outbreak is always just two beetle generations away. Historically, outbreaks in the coastal plains occur shortly after climatological changes. The change is usually from drought to excess soil moisture. Although this change took place last year, an outbreak has not yet occurred. Last year, pine mortality occurred due to water table fluctuation, but the insects involved were either Ips species or Black Turpentine beetles. The worst case scenario I see for the coast is a lot of lightning strikes early in the summer followed by one or more inundations from summer hurricanes. The beetles could build quickly in the lightning struck trees and begin a coastal outbreak late in the summer or early in the fall.
These trapping data results are for entire counties and there is always the possibility of sporadic and localized beetle activity in counties with overall predictions of low population levels. Activity is most likely in susceptible pine stands which are overstocked, overmature or stagnant, have poor drainage or have littleleaf or other root diseases present and causing stress.
We will be conducting aerial surveys throughout the areas containing beetle infestations and notifying affected landowners that beetle spots are present on their properties. Since our surveys are of entire counties, many industries and consultants perform supplemental aerial surveys of their holdings.
Although the drought is officially over, the trees that have been stressed by it may not recover their health for years. There remains a possibility of losses to other pine bark beetles that are not normally very aggressive. Ips and Black Turpentine Beetles often continue to cause mortality until the pines have fully recovered. Since these insects require different control tactics than SPB, it is important to determine which insect is causing each infestation. Ips beetles can be identified by their galleries that are usually H or I shaped rather than the winding galleries of southern pine beetles. Adult Ips beetles also eject the frass from their galleries while the SPB packs its galleries with frass. The black turpentine beetle attacks the basal portions of the trunk and is a much slower killer than SPB or Ips. We can assist with this identification or provide training where needed.
In summary, in the piedmont we can expect a year of minimal loss to southern pine beetle and related bark beetles. The coast may be poised for some degree of loss, especially if we have additional stress factors. Control by commercial salvage is effective in stopping any of the bark beetles infesting pines. Another possibility for control of southern pine beetle only is the cut and leave technique. In this control strategy, infested trees and a buffer of apparently uninfested pines are cut but not salvaged. This method works best from May - October due to high daytime temperatures and SPB biological factors. This is not effective for Ips spots since those insects breed and mature easily in cut pines. If needed, the Forestry Commission will reactivate our cut and leave program for private landowners who request this service.
Another potential insect problem we have been monitoring is the development of bark beetles in ice damaged pines. We established 21 plots in the impacted area in pine stands with varied degrees of damage. Presently, about 15% of the broken tops on the ground have been infested by Ips species. These beetles are now emerging as adults and will probably disperse (the tops are now too dry for additional infestation). Approximately 3% of the standing boles with no branches have been attacked by Black Turpentine beetles. This number should rise with time and these beetles may build a large population and attack some green trees. Attempts to induce attacks on these boles by Southern Pine beetle were unsuccessful (we put SPB pheromone pouches on broken standing boles and none were attacked by SPB). It is highly doubtful that SPB will attack these boles in the future. We will continue to monitor these plots and will advise you if changes occur.
Please contact us if you have any questions or if we can provide additional information.
Some links on this page require Adobe Acrobat Reader. If you don't have Acrobat Reader you can get it free from Adobe Systems Inc. Adobe(R) Acrobat(R) Copyright © 2010 Adobe Systems Incorporated. All Rights Reserved.