![]() Fraser fir seeds (pictured above) are collected each year from mature, cone-producing trees and shipped to growers nationwide. “It’s really a big problem for growers, because they might be buying and planting infested seeds that look completely healthy,” Matallana said. As a result, infested seeds are often deposited with healthy seeds during the cleaning process. Growers often have difficulty identifying chalcid infestations, because infested seeds not only appear normal on the outside but also weigh about as much as healthy seeds. Protecting the Seed SupplyĪlthough chalcid infestations aren’t currently considered a major threat to North Carolina’s Christmas tree industry, they could eventually become a costly issue for growers, according to Matallana. “The proposed research will contribute basic and practical knowledge to improve seed quality and leverage chalcid development to control future infestations in other fir orchards in North Carolina,” Matallana said. Ross Whetten, a professor in Department of Forestry and Environmental Resources and member of NC State’s Molecular Tree Breeding Lab, to determine clone-specific infestation rates before and after pesticide treatment and to identify candidate clones with reduced susceptibility to Megastigmus specularis and other chalcids. With funding from the North Carolina Christmas Tree Association, Matallana is now working with Dr. Additionally, the team found that pesticide treatment may impact infestation rates. Previous work by Matallana and other NC State researchers suggested that there may be genetic differences in Megastigmus infestation rates among trees in clonal seed orchards, and that these differences could affect the cost of planting stock for Christmas tree growers due to downstream impacts on the viability of seeds from the same clone during long-term storage. Watch: Parasitic Wasp Larva Emerges from Christmas Tree Seed These attributes provide a considerable increase in income for Christmas tree plantation owners across the state. Trees derived from clonal seed orchards have more desirable characteristics than trees that originate from seeds collected in natural stands. ![]() The state’s Christmas tree industry is mainly supplied with seeds from natural stands and genetically-improved material from clonal seed orchards, according to Matallana. Nearly all of the state’s trees – 96 percent – are Fraser firs, mostly grown in 14 mountain counties. North Carolina produces more than 6 million Christmas trees each year, about 15 percent of the nation’s natural Christmas trees – second only to Oregon. But, because of increased interest in growing Fraser fir for Christmas trees, information about the effect of these insects on the state’s seed supply is needed. Until recently, there was little reason to be concerned about Megastigmus specularis and similar species in North Carolina, according to Matallana. Matallana said this cycle – which leaves seeds inviable for commercial planting – is repeated annually except some larvae delay emergence for an additional year or more, presumably to preserve the species in case of crop failures. Once the egg hatches, the larvae feed on the seed until they’ve matured. Females then fly to developing cones and use an elongated ovipositor (like a modified stinger) to drill into the seeds and deposit their eggs. The tiny wasp – about 3 mm long – overwinters in fir seed on the ground, with adults emerging in spring. Female Megastigmus specularis isolated from Fraser fir seeds in the Molecular Tree Biology Lab. Photo by Matt Bertone of the NC State Plant Disease and Insect Clinic. It mostly infests Fraser fir trees in the Appalachian Mountains, according to Dr. Lilian Matallana, a research associate at NC State’s Department of Forestry and Environmental Resources. Originally described in the 1930s, Megastigmus specularis is one of several thousand species of chalcid wasps. That includes parasitic wasps that eat the seeds of Christmas trees before they ever get the chance to grow. In North Carolina – which is the second-largest producer and exporter of Christmas trees – growers face changing weather patterns, diseases, and a number of other challenges that could potentially prolong the shortage. Seeds are harvested from the cones of mature Christmas trees – and because it can take several years for trees to reach maturity, the shortage is likely to continue beyond 2019. In recent years, however, some growers in major tree-producing states like North Carolina and Oregon have struggled to remain profitable amid a looming shortage.Įxperts with the National Christmas Tree Association and NC State Cooperative Extension say the shortage is partly a result of the 2008 recession when decreased demand led growers to plant fewer seeds. Whether it’s bought at a retail lot or farm, a live Christmas tree is an integral part of the holiday season for millions of Americans.
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