This story also appears in our University of Missouri College of Agriculture, Food and Natural Resources’ Agricultural Research Center Magazine. Stop by your local Research Center to pick up a copy!
While the chestnut is not as common as other specialty nut and fruit crops grown in the United States, the tasty treat has found a home at the University of Missouri College of Agriculture, Food and Natural Resources’ Horticulture and Agroforestry Research Center (HARC), near New Franklin.
HARC has been the primary location for the MU Center for Agroforestry chestnut research for the past 20 years, with 65 different cultivars spread over seven acres. There are about 550 chestnut trees at HARC.
“It’s been a step-by-step process,” said Mike Gold, interim director of the MU Center for Agroforestry. “In the late 1990s, we had no clue how well chestnuts would do – if they would thrive in river hill soil, if we had the right spacing, if we should use irrigation, if we had the right climate, if we could identify superior cultivars, or if the prices and markets would support a new specialty crop industry. It took well over a decade of sustained research to answer those questions.”
Ken Hunt, a research scientist with the Center for Agroforestry who retired in 2011, established all of the 550 chestnut trees at HARC. Hunt, an amateur nut grower, had Chinese chestnuts growing on his property. When the agroforestry program at MU joined the Horticulture Research Center in 1993, to form HARC, Hunt had extra room to experiment. He began grafting chestnuts at HARC in 1996.
“Ken was the guy when it came to chestnuts,” Gold said. “Other than a small test planting to study fertilization levels and a small new planting in 2016, he established every chestnut tree that is growing at HARC.”
The first question going into chestnuts productions was whether or not the soil at HARC would allow for chestnuts to flourish. Chestnuts need excellent soil, a lot of water and good drainage. Researchers quickly found that chestnuts do just fine at HARC in the rich, well-drained, menfro silt loam soils found throughout the Missouri river hills region.
The second question was related to Missouri’s climate.
“The trees seem to really like our hot summer weather,” Gold said. “If you put trickle irrigation down, and provide moisture at the ground level, the chestnuts thrive in that heat. Our Missouri summers serve chestnuts well.”
While adequate moisture is essential, drainage is also incredibly important for chestnut trees. Gold said that it takes just two to three days of standing water to greatly increase the possibility of losing a tree to phytophthora root rot.
The sequence of chestnut orchard establishment at HARC occurred in four phases. The first planting, initiated in 1996 and added to for the next decade, was set up as a germplasm repository to include a large collection of 65 chestnut cultivars. The second orchard was set up to test 15 cultivars, with five trees per cultivar. The third orchard included three cultivars in three tree plots with eight repetitions throughout the orchard. This orchard simulates a true production orchard. UMCA researchers have collected data on each of these orchards during the past 15 years. The fourth orchard, established in 2007, was set up to test chestnut pollen flow.
“The 15 cultivar replicated study was established in 1999,” Gold said. “The production orchard currently planted with Qing, Peach and Kohr was established in 2001.”
Kohr was not among the original three cultivars, however, after initial promise, Willamette proved to be a poor cultivar and was replaced.
For all HARC germplasm plantings, Hunt created grafted chestnut orchards. Grafting is a common horticultural technique where scion wood taken from the crown of proven cultivars is grafted onto compatible rootstock. All commercial fruit and nut orchard industries are based on the use of cultivars, a form of clonal propagation. Cultivars of any fruit or nut crop will be very consistent in multiple growth and yield attributes. In areas where chestnut cultivars are “iffy,” seedling orchards can also be used established. Seedlings are hardier, grow faster and grow taller.
“For us, in the Missouri river hill soils, grafted chestnut cultivars do exceptionally well,” Gold said. “Plus, if we plant 300 trees, we want 300 winners. If they’re seedling-derived trees, you will get fewer superior trees and a great deal more variability between each tree in terms of yield and nut size. Seedling trees also take at least three additional years to come into commercial production.
“In other regions, the climate isn’t as ideal for cultivar production, so growers are more comfortable planting seedling trees derived from the proven cultivars. A lot of individuals buy seed from HARC chestnut orchards knowing that the genetics are good.”
Chinese chestnut cultivars are the preferred option for growers in Missouri and adjacent states – and are one of the important germplasm collections at HARC. HARC has the largest collection of Chinese chestnut cultivars in the United States.
“In our region, Chinese chestnuts are desired by the growers and the local markets” Gold said. “After 20 years of study, we have a large degree of confidence in recommending selected Chinese chestnut cultivars to growers.”
The chestnut harvest runs from mid-September to mid-October. The first chestnuts drop in early September – with the peak times from September 20 to October 5.
“It literally rains chestnuts at HARC during this time,” Gold said.
To collect chestnuts, Center researchers and HARC staff originally used a harvester designed for pecans and walnuts. The shape of chestnuts, with a round side and a flat side, presents a problem for this style of harvester. The rubber fingers on a pecan or walnut harvester can sometimes push the chestnut into the ground instead of picking them up.
“We recently received a specialty crop grant from the state and purchased a commercial chestnut harvester from Italy,” Gold said. “This type of harvester is a vacuum harvester. It sucks the chestnuts up, separates the nuts from the bur, making sure we harvest the entire crop.”
“We also do a lot of hand harvesting, especially when collecting data and when collecting seed from individual cultivars.”
Nutritionally, chestnuts are different than other nuts including walnuts or pecans. Walnuts and pecans are heart healthy with large amounts of healthy fats and oils. Chestnuts have 50 percent moisture content at harvest and require refrigeration for a long shelf life. Chestnuts also contain as much Vitamin C as lemons and are high in fiber and very low in fat. If left out at room temperature for a few days, chestnuts will cure and sweeten. However, if left at room temperature for a week or more, chestnuts will mold and dry down to hard nuggets.
“Chestnuts offer a different nutrition profile,” Gold said. “They are in the same botanical family as oak and beech trees, yet produce a very tasty nut.”
The Center for Agroforestry researchers are actively involved in the Chestnut Growers of America, conduct regular chestnut market surveys and communicate regularly with growers about market trends. Because working with growers is a two-way street, learning from growers’ experiences is vital to inform future research directions. Center researchers cover topics such as chestnut pricing and demand trends. In 2009, Center researchers received a grant and offered a four-part workshop series from 2009-2011, focused on chestnuts – soils, cultivars, grafting, maintaining the crop, harvesting the crop and marketing the chestnuts.
“We want to provide the entire package of required knowledge for landowners that we work with,” Gold said. “It is an ongoing process as new research is brought to light and changes occur in the marketplace. We’re always looking to find new opportunities for Missouri landowners to earn a living on their family farms.”
To introduce consumers to chestnuts, the Center began its annual Chestnut Roast at HARC in the fall of 2003. It’s the Center’s signature event.
“It’s a great opportunity to showcase our research on chestnut and other specialty crops, while offering landowners and families a pleasant day with the family out in the beautiful Missouri river hills,” Gold said. “In Missouri, the Midwest and throughout the US, the emerging chestnut industry is poised for rapid growth.”