EAB parasite could be future biocontrol
Chinese researchers identified an undescribed parasitoid of emerald ash borer, according to North American Plant Protection Org. Several parasitoids were found in China, including a new Tetrastichus wasp species. T. planipennisi Yang parasitizes EAB larvae. It produces 56-92 offspring from a single EAB host. The parasitoids develop from eggs to larvae within an EAB larva, which remains alive until its last instar. Wasp larvae emerge from the dead EAB larva and chew exit holes through the bark of the tree. These wasps may have four generations per year in northeastern China. The discovery may provide biocontrol measures for North America, where the EAB has destroyed millions of ash trees.
Florida reveals 2007 plants of the year
Fla. Nursery, Growers & Landscape Assoc. announced its 2007 plants of the year. Galphimia gracilis (USDA Hardiness Zone 9) is a drought-tolerant, evergreen shrub with blue-green foliage. Eragrostis spectabilis (Zones 5-9) is a perennial grass with leaf blades up to 12 inches long. Cyrtomium falcatum (Zones 8-11) is a low-growing, clumping, evergreen fern. Zamia maritime (Zones 9-11) is a cardboard palm that features exotic-looking seed cones. Dracaena deremensis 'Limelight' is FNGLA's interior plant choice. It features bright, glossy, lime-green leaves.
Publication names storm damage-susceptible trees
Univ. of Ill. at Urbana-Champaign and Univ. of Wis.-Stevens Point partnered to produce "Trees and Ice Storms: The Development of Ice Storm-Resistant Urban Tree Populations." The new publication helps growers, city planners, landscapers, retailers and consumers understand which trees are susceptible to ice storm damage. Management plans for urban trees should incorporate information on the ice-storm susceptibility of trees to limit potential ice damage, said Jay Hayek, Univ. of Ill. forester.
Winter hazel makes P. ramorum list
At the end of 2006, the Canadian Food Inspection Agency added the genus Corylopsis to its list of plants regulated for Phytophthora ramorum, the sudden oak death pathogen. Corylopsis, winter hazel, is a deciduous shrub that produces pale-yellow flowers in March. It has many species, mostly hardy in USDA Hardiness Zones 5-8. The Canadian list of regulated plants differs from the USDA list.
Study: Broad live oaks are dying off
Univ. of Fla. researchers say live oaks (Quercus virginiana) in both suburban and rural areas are losing the battle for survival. This is due in part to the encroachment of taller trees. "Broad-crowned live oaks thrive in open savannas but are dying off as they are crowded and overshadowed by the encroachment of taller trees," said Francis Putz, Univ. of Fla. botanist. "If we allow other trees to grow up too close to the live oak, the live oak will die. Our research clearly establishes this fate in both rural and suburban landscapes." The worst offenders: Laurel oak, sweet gum, black cherry and magnolia. More than half of the live oaks in Gainesville are in danger of being destroyed by encroaching trees, a process that can take 10-30 years and is most rapid in the suburbs where lawns are fertilized, Putz said.
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