Fall Is Chestnut Time – Master Gardener Scoop, October 11, 2017

By Linda Summers,
Master Gardener

Over the past week and a half, our Chinese chestnut trees have been dropping their chestnuts. Every morning, my husband searches the ground for chestnuts, hoping to collect them before the squirrels do!

The Chinese chestnut, or Castanea mollissima, is native to Northern China and Korea. Introduced in 1853 and 1903, it has become a replacement for the American chestnut (Castanea dentata), which largely disappeared over the first half of the 20th century. The American chestnut once dominated the landscape along the eastern U.S. and as far west as Michigan. It grew to a height of 100-150′ with a trunk diameter up to 10′. Prized for both its nuts and its hardwood, the American chestnut became vulnerable to an introduced fungus, Cryphonectria parasitica, or chestnut blight, which girdles the tree although not affecting the roots. Hence, there is widespread sprouting from the old roots, which later succumb to the blight. In less than 50 years, the American chestnut population dwindled from 3.5-4 billion trees down to a few hundred trees.

The Chinese chestnut, which is highly resistant to chestnut blight, grows to a height of 40-60′. They do well in most locations in Illinois, although they prefer well-drained, loamy soil and full sun. They also seem to do well in dry, hot climates. The Chinese chestnut is not recommended for planting in Northern Illinois, but they do fairly well in Central and Southern Illinois. Plant any two of the following varieties for cross-pollination: Eaton, Qing or Orrin.

The lustrous dark green leaves are alternate, simple and grow 3-6″ long and 2-3 1/2 ” wide. The leaves are also coarsely serrate with bristle-like teeth. In the fall, the leaves change to yellow or bronze and often don’t fall off the tree until late in the season. The nuts, of which there are two-three, are encased in a prickly bur, which splits at maturity into two-four valves.

The nuts may be used in any number of dishes. My family chops them up and adds them to a poultry dressing. Perhaps, the most common way of preparing chestnuts is roasting. Be sure to puncture the shell before roasting, however, or you will have exploding chestnuts.

According to Elizabeth Wahle, University of Illinois Extension educator, “Chestnuts may be roasted over an open fire for 15-20 minutes with constant motion; roasted in a conventional oven at 300-325°F for 15-20 minutes; boiled or steamed for 10-15 minutes; or micro-waved wrapped in damp paper towels for 45-50 seconds on high.

Regardless of the heating process, peeling is easier if nuts are allowed to cool just enough to handle without injury. As nuts cool, peeling the pellicle from the kernel becomes an ever-increasing challenge.”

Chestnuts should be kept in the refrigerator, in a ventilated plastic bag, up to a couple of weeks. After removing our chestnuts from the shell, we freeze chestnuts for use at a later time.

And what is happening with the American chestnut tree? Since the 1950’s, researchers have worked on developing a blight free American strain. Dr. Robert Dunstan of North Carolina grafted a blight free American strain onto a Japanese chestnut. When it flowered, he crossed it with a Chinese chestnut. Using progeny from this cross, he backcrossed it to the American parent. The American Chestnut Foundation partnered with the U.S. Forest Service and universities to achieve more promising results. The result has been an blight resistant American chestnut that retains 94% of the American chestnut genetics. To date, a few thousand of the trees have been planted across North Carolina, Tennessee and Virginia.

For more information, please contact your local Master Gardener or call or visit your local University of Illinois Extension Office.

Another great source of gardening information is the Extension website at extension.illinois.edu.