Impact of Systemic Fungicides on Lesions Formed by Inoculation with the Bluestain Fungus (Ophiostoma minus) in Loblolly Pine (Pinus taeda L.)

Ophiostomatoid fungi are important components within the highly damaging insect-fungal complexes attacking trees in North America. This group includes the disease agents responsible for Dutch elm disease and laurel wilt, as well as a number of associates of tree-killing bark beetles. While systemic fungicides have been applied against ophiostomatoids in certain fungus-host systems, the breadth of their utility and their management implications for a wide array of fungus and host species remain uncertain. To evaluate the impact of commercially available fungicides against the bluestaining fungus Ophiostoma minus, an associate of the southern pine beetle, researchers conducted two experiments with loblolly pines (Pinus taeda; mean dbh 14.2 and 18.5 cm, respectively) in central Louisiana, U.S. The first experiment screened three fungicides (Alamo®, Arbotect® 20-S, and PHOSPHO-jet) for their systemic impacts on O. minus, and the second further evaluated the best performing product (Alamo) alone and in combination with Arbotect 20-S. In all cases, loblolly pines were stem-injected basally and challenged with inoculations of cultured O. minus at time periods ranging from 28 days to 738 days post-treatment. In both experiments, treatment of loblolly pines with Alamo produced the smallest lesion areas, indicating that this treatment was the most effective for limiting the within-tree growth of O. minus. This effect was still present more than two years post-treatment. The study authors conclude that Alamo is the most effective product of those evaluated for prophylactic treatment against O. minus, and suggest that evidence is building for the effectiveness of this product generally against ophiostomatoid fungi.

Recovery of Planted Loblolly Pine 5 Years after Severe Ice Storms in Arkansas

Following a severe ice storm, one of a landowner's first considerations regarding the future of their damaged stands should be on the recovery potential of injured crop trees. The ice storms that struck Arkansas in December 2000 provided an opportunity to monitor 410 injured loblolly pines (Pinus taedaL.), representing a wide range of damage in 18–20-year-old plantations. Five-year mortality rates were <3% for trees with low to moderate injury, 16% for major damage, and 55% for critical damage. Of the most seriously affected pines, root-sprung trees had the highest periodic mortality rate (85%). Annualized diameter growth was significantly affected by the tree's dbh class (positively) and intensity of damage (negatively). This research suggests that pines with low to moderate levels of damage can prove to be acceptable growing stock, whereas critically injured individual trees are not. Trees with major damage could be either retained or salvaged, depending on residual stand stocking, the operability of the salvage, and existing market conditions. Finally, recommendations from this study should enable landowners to better respond to their loblolly pine plantations damaged by ice storms.

Reorientation Strategies in leaning stems of young maritime pine (Pinus Pinaster) and Loblolly Pine (Pinus Taeda)

To test for different stem reorientation strategies in leaning seedlings of maritime pine (Pinus pinaster Ait.) and loblolly pine (Pinus taeda L.), we inclined dormant plants at 0°, 45° and 90° for 35 days in optimal growthconditions. Stem angle to the vertical was measured at regular intervals. After 22 and 35 days, bending tests were carried out to determine stem elasticity and stiffness. The quantity of compression wood (CW) formed was also measured. Results showed that after 24 h, the apices of leaning maritime pine stems had completely reoriented to the vertical, whereas no such primary tropic response was observed in loblolly pine. After 22 days, the significantly stiffer loblolly pines had begun straightening up from the stem base, but not maritime pine. After 35 days, the overall secondary reorientation process was more efficient in loblolly pine, with significantly more CW produced. In both species, CW had formed immediately on tilting stems, i.e. no early wood cells had formed. As maritime pine originates from a dry to semi-arid region, having less CW will mean that water uptake will be greater for the same xylem area compared to loblolly pine which possesses more CW. In establishing maritime pine seedlings, rapid apical orientation with regard to light and gravity will compensate for a slower straightening up mechanism in the more lignified parts of the stem. Therefore, juvenile needle exposure to patches of light will be maximised at all times.

Pre-Commercial Thinning Loblolly Pines – Does It Pay?

FOR-188, a 5-page illustrated fact sheet by R. A. Williams, K. Bohn, and J. McKeithen, describes methods and silvicultural and economic benefits for reducing tree density before the trees reach merchantable size. Includes references. Published by the UF School of Forest Resources and Conservation, June 2008.

Survival of Longleaf and Loblolly Pines Planted at Two Spacings in an East Texas Bahiagrass Silvopasture

The practice of combining intensive timber and forage production on the same site, a silvopasture system, offers landowners the potential for diversification of income. The establishment of such a system in a pasture setting offers unique challenges compared with traditional timber or forage systems. In 2003, a silvopasture demonstration was established south of Carthage, Texas, in a pasture dominated by bahiagrass (Paspalum notatum). Four replications of treatments composed of open pasture, longleaf (Pinus palustris) and loblolly (Pinus taeda) pine planted at a traditional spacing, and longleaf and loblolly pine planted at a silvopasture spacing were established. Due to high mortality rates, replanting of trees occurred in 2004 and 2005. Third-year seedling survival was highest for loblolly pine in both planting systems, and forage production levels did not significantly differ among treatments. Wild hog damage contributed to the low longleaf pine seedling survival rates.