Each spring, owners of apricot trees hope this will be the year they have fruit. Apricot trees are one of the first fruit trees to blossom and late spring frosts frequently kill the blossoms prior to fruit setting on the trees.
Because of the weather, apricots are one of New Mexico’s smaller crops. According to the New Mexico Department of Agriculture annual agricultural statistics, 210 farms harvest 75 acres in Doña Ana, Otero and Rio Arriba counties.
New Mexico State University researchers are seeking economical ways for growers to raise apricots in northern New Mexico. Cooperative Extension Service fruit specialist Shengrui Yao is working on the concept of growing the trees in hoop houses to provide frost protection.
NMSU agricultural researchers have conducted several studies on how hoop houses can be used to extend the growing season, including raising blackberries in the hoop house.
“The apricot study is to see how much fruit yield and revenue can be made compared to the cost of protecting the blossoms in the economical hoop house design,” Yao said.
Last year, Yao’s study at the Sustainable Agriculture Science Center at Alcalde produced its first crop of fruit.
“The trees are growing in the defused light environment of the hoop house,” Yao said. “But, during the first two years, while the hoop houses gave them some protection from the cold, we still had blossoms killed by the late frost that can happen through May 15 at Alcalde.”
At first, Yao relied on a manually ignited propane burner, but found the New Mexico climate regions unpredictable for relying on weather forecasts when determining when to turn on the burner.
“When the forecast was for 35-38 degrees, we thought the blossoms would be safe, but they weren’t because it was colder here near the Rio Grande,” she said. “Some growers rely on an alarm that sounds when the temperature nears 32 degrees so they can ignite the heaters. Here at the research farm, that method was not possible.”
In 2015, to resolve the issue of providing heat when the plants need it, Yao installed a thermostat inside the hoop house that was programmed to ignite the propane burner when the temperature dropped to 32 degrees.
“It worked. We had our first crop of apricots last year,” she said. “The cost of propane was minimal, so this method could work for a grower.”
The second part of the study is to determine how to arrange the trees in the hoop house to have maximum space for fruit-producing branches, which impacts the crop yield.
The replicated study has trees planted in two hoop houses. One house has the trees planted in the traditional spindle system with the trunks perpendicular to the ground. In the other, Yao is testing the upright fruiting offshoots system by planting the tree trunks at an angle to the ground.
“The UFO method was first tried on sweet cherry trees,” Yao said. “I’ve adapted it to the apricot trees to see which technique is more productive.”
The UFO system keeps the canopy lower than the spindle system and allows more space for the new growth where fruit is produced. It also allows growers to prune the branches when they no longer bear fruit.
“The trees in the spindle system produced 40 percent more fruit than UFO system,” Yao said of the first harvest. “However, the trees in the UFO system had relatively bigger fruit, which could be due to the low crop load.”
With success in preventing frost damage, the researchers plan to continue monitoring the yield and fruit of those two training systems in coming years.