A total of 31 S.C. counties were trapped for SPB in 2005 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 29 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, only Chester, McCormick, and Newberry Counties trapped sufficient beetles in all traps to receive a prediction of increasing – high pine mortality. In Edgefield and Horry Counties we can expect losses similar to those recorded in 2004. The other 26 counties we sampled had fewer beetles trapped and are not expected to have widespread problems. These counties include Abbeville, Anderson, Beaufort, Berkeley, Charleston, Cherokee, Colleton, Dorchester, Fairfield, Georgetown, Greenville, Greenwood, Hampton, Jasper, Kershaw, Lancaster, Laurens, Lexington, Oconee, Pickens, Richland, Saluda, 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 continued sporadic SPB activity even 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 was almost exactly the same as last year’s total and the number of clerids dropped by 50%. This clerid population is still fairly high and should constrain SPB development in most areas of the piedmont, but we still expect problem areas as outlined above. Also, the distribution of clerids was not uniform and less than 10% of the traps caught 90% of the total clerid catch.
In the piedmont, Edgefield and McCormick have been in outbreak status for six years. Usually, an extended outbreak indicates less aggressive spot expansion as the beetles and predators reach equilibrium. We expect losses to continue there at a moderate level. In Newberry and Chester Counties, no significant losses have occurred since 2002. Losses in the first years of a new outbreak can occur more quickly and spots can expand faster with less clerids present to eat the beetles.
In the coastal plains, the clerid/ SPB ratio is more favorable than last year and only Horry County seems poised for a beetle outbreak. One interesting fact is that our hottest coastal trap was close to the North Carolina State line. We have not yet seen their pheromone data, but if it is comparable to what we detected, that may indicate the beginning of an upper coastal plain outbreak in both states. Historically, outbreaks in the coastal plain occur shortly after climatological changes. The change is usually from drought to excess soil moisture. The four hurricanes that hit South Carolina last year did drop significant rainfall, much of it in the upper coastal plain. Again this year, the worst case scenario for the coast would be a lot of lightning strikes early in the summer followed by one or more inundation from summer hurricanes. This could allow beetle populations to build quickly in the lightning struck trees to intensify any outbreak, especially in Horry County.
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 to quantify damage. If enough damage is present, we will fly 100% surveys and notify 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.
Ips and Black Turpentine Beetles continue to cause mortality in overstocked stands and in areas where excessive rainfall coupled with impermeable hardpan caused some drowning of roots. 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, most of S.C. can expect a year of low-level loss to southern pine beetle and related bark beetles. However, Chester, Edgefield, Horry, McCormick and Newberry Counties 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 that request this service.
It is difficult to predict the degree of loss to SPB since environmental factors affect this. However, our “guestimate” for S.C. is for loss between $10 - $20 million. As usual, a hot summer with extended temperatures over 100 degrees Fahrenheit should constrain beetle development.
Another ice storm occurred in December 2004, although it caused nowhere near the losses of the storm of January 2004. Forestry Commission aerial surveys detected approximately $1.1 million in damage to pine pulpwood in six South Carolina counties. These were Chesterfield, Darlington, Dillon, Kershaw, Lee and Marlboro counties. A listing of loss by county is included for your records.
Please contact us if you have any questions or if we can provide additional information.
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