Throughout Nebraska and the Great Plains, people have a love-hate relationship with cedar trees.
They are used extensively for windbreak plantings, but ranchers generally hate cedars in pastures, where they take up space and reduce the amount of grass that is available for cattle grazing.
Researchers in Kansas are developing a way to keep the trees from spreading to places they are not wanted.
The key is to capitalize on a characteristic that cedars have — they are dioecious. That means they produce pollen on some male trees, and seed-bearing cones on separate female trees. If people had an inexpensive source of young trees that they knew would never produce seeds, the problem might be solved.
Currently, windbreak cedars are grown from seeds and nobody knows which are male and which are female for as long as 15 to 20 years after planting, when the trees are out of their juvenile stage.
The best solution could be to produce rooted cuttings from male cedar trees for windbreaks.
Ryan Armbrust, a forester with Kansas Forest Service based in Manhattan, is leading the research. He said he hopes that within five years they will be ready to distribute rooted, male cedar cuttings for people to plant in their own windbreaks for further evaluation. A few years after that, if things are going well, the trees may become available commercially at an affordable price.
There are three parts to the project, Armbrust said:
The first is to get the cuttings to root at a reasonable rate of success; they normally do not root as readily as cuttings from many plants. Researchers are encouraging rooting by dipping the cuttings into a liquid blend of certain plant hormones, then placing them in a mixture of perlite and peat moss, commonly used in the nursery trade for that purpose. They typically do that in February. The cuttings are kept moist under misters for the 20 weeks or so that are required for callus to form and sufficient rooting to take place. Those that have rooted successfully are placed in pots with potting soil in the greenhouse.
The next spring, they are planted outdoors at Kansas Plant Materials Center, also in Manhattan. Over two to three years, researchers watch the young trees to see if they thrive in the field.
The final step will be to see whether the trees have the proper form as they grow. There is a risk that trees grown from branch cuttings will grow too wide, but not tall enough, Armbrust said.
Fred Cummings is manager of KSPMC. He said the rooted cuttings they planted a year ago look like they are doing well. So far, so good.
Armbrust has been trying different combinations and concentrations of plant hormones over the last couple of years, to see which give the best results.
“I think we’ve developed the best sweet spot,” a combination that yields a 20% success rate, he said. That is “something we can live with.”
He actually picked up where Richard Gilbert, nursery manager at the Bessey Tree Nursery in Halsey, left off. Gilbert did cedar cutting work at the nursery from 2008 to 2011, but ran out of time and space to continue. He said he was getting a 1-2% rooting success rate.
“I think it’s wonderful” that Armbrust is carrying on with the work, Gilbert said. “I was looking for someone to take over the project and devote the time needed,” when Armbrust approached him.
Gilbert’s interest is long-lived.
“We messed around with trying to root cuttings (from cedars) at UNL” from 1995 to 2000, he said. He was working in a greenhouse on the campus in Lincoln then, splitting his time with the Nebraska Statewide Arboretum.
Armbrust is using his own research to fill a requirement for a master of science degree in horticulture, but said the project will not end when he gets his degree.
“We view this an important issue for the Great Plains. Eastern redcedar is a critical species for windbreaks,” he said.
Over the last several years, the pine wilt nematode destroyed many Scotch pines, which had also been an important windbreak evergreen, Armbrust said. That makes cedars all the more important.
As old windbreaks are renovated or new windbreaks planted, the research could increase the benefits of a tree well suited to growing conditions in the Great Plains, while reducing the frustration of farmers, ranchers and landowners who want to keep cedars in their place.