Post-harvest care important for Christmas trees
NATURAL BRIDGE, Va. — Retaining needles and keeping trees fresh after they have been harvested is a continuing challenge for the Christmas tree industry.
Members of the Virginia Christmas Tree Growers Association learned some of the ways this can be done during their annual convention in August.
Dr. Rick Bates from Penn State University, discussed species of trees as well as methods in his talk “Post-Harvest Needle Retention/Freshness and Why It’s Important.”
Temperature changes are an important factor in trees going dormant, Bates said, and growers need to look at what influences the trees as the weather cools.
Conifers track temperature, he added, responding to the changes in fall weather. This happens in two stages. The trees respond to the shortening of the days and then frost on a tree brings it into dormancy. He said the more frost, the more dormancy, the better for freshness.
Bates cautioned against cutting trees too early for shipping, especially in October, before they are dormant. He said Cannan firs not allowed to go dormant means the grower is looking at trouble.
He added, however, the Korean fir, unfamiliar to most of his audience, does not respond this way.
Spider mites can also be a cause of needle loss, Bates said.
Factors in needle retention or loss include temperature, relative humidity, rainfall, wind and sunlight.
“They all conspire to close moisture out of the tree once you cut it,” Bates said.
He called for audience participation, asking the growers what they do to prevent the loss of moisture in their trees.
“Shade” came quickly from a member of his audience. He asked about what kind of shade. Answers included barns, lath structures and fabric structures. Baling is another way to prevent moisture loss, he noted.
“Keep them baled,” he said. “Bale quick. Wind is your enemy. Keep them baled.”
Bates urged each grower to think about the way harvest is done on the individual farm.
He said growers do not want the trees to be packed too closely as heat can build up leading to mold or even fire.
He told the group that trees need to be cut only in the morning during dry weather. This is because most moisture is lost early in the morning. He said an unbaled tree can lose 50 percent of its moisture in a day.
Growers also need to be aware of string burn, trunk splitting in really high moisture trees, the need for developing efficient systems for truck loaders and protection during transportation.
“Pay attention,” he stressed. “You may be missing something. Temperature change can change dramatically from sun to shade.”
Educating the customer is another part of ensuring that trees retain their needles after they are cut and sold. He pointed out that re-cutting the trunk is important to make sure the tree can absorb water.
Bates noted a cut tree can absorb up to a quart of water per inch of stem diameter in a day.
“Address the issue of how do we supply water to trees in homes,” he told the group.
He said some tree stands are a disaster, with no way to help a tree rehydrate. He urged the growers to learn what works and to explain it to customers.
“We need to be combating things that are not food for the product,” he said.
1-800-634-5021 410-822-3965 Fax- 410-822-5068
P.O. Box 2026 Easton, MD 21601-8925