MANKATO — October in Minnesota is a time when tree-lined city streets can turn mean.
Pedestrians have to dodge green-shelled black walnuts that drop without warning from their parent trees.
Motorists must swerve to avoid hitting squirrels darting back and forth on the road, distracted by the abundance of their favorite food.
Homeowners must deal with the mess and stains left by the rapidly decaying green cover of the black walnuts.
Minnesota Extension Service advises drivers against driving over the broken nut shells, which are so hard and sharp they can cause bodily injury and property damage if sent flying.
But black walnuts have their fans as well. They prefer the taste of the black walnut to that of the milder English walnut, the traditional holiday treat.
Alex Palmer is not easily deterred by the problem of getting to the meat inside the hard and stain-producing shells. He answered a request from The Free Press for tips on cracking the nuts open.
“I just gather them up, clean them up and leave them to dry for a week. Then I put them in a clean towel, place them on a cinder block and lightly hit them with a hammer.”
A faction of gardeners and homeowners consider the walnut — and the squirrels who are attracted to the food source — to be backyard enemy-combatants.
Fred Struck, owner of Traverse des Sioux Garden Center in St. Peter, does not sell black walnut saplings and he's not fond of squirrels.
“They can be nasty, like rabbits,” he said.
For 20 years, Sean Francis has been in the business of removing squirrels from attics and garages and closing up holes the rodents chew to gain entry in houses.
Francis has had squirrels jump atop his head and then down his body on the way to the ground.
His advice to others who have been used as substitute tree trunks by squirrels: “Just let them.”
Francis was bit in the finger when he’s tried to unattach a squirrel — its sharp teeth cut through the heavy leather glove he was wearing. Francis, the owner of Falls Creek Animal and Pest Control, advocates removing the animals by using a live trap attached to the holes they create. Squirrels are captured as they exit a building, then relocated.
“I take them about 10 miles away — it has to be at least 8 miles as the crow flies,” Francis said.
Squirrels will make heroic efforts to come back to their nesting site and the black walnuts they've been saving for the winter months.
The little animals will collect bushels of nuts each fall and they are creative in finding places to put them. Francis told of a family whose brand-new RV was used as a squirrel storage bin.
“A little red one filled its air conditioner unit with nuts. There were buckets full.”
Francis gets more inquires about walnut tree removals than about where to buy or sell the nuts.
“Beginning gardeners soon see the direct results of planting too close to juglone,” Struck said, using the scientific name for walnut trees.
The roots of a black walnut tree release a substance into the soil that can stunt the growth of nearby plants. The toxin spreads about 50 feet from the tree’s base, he said.
“Tomato plants and apple trees shouldn’t be planted anywhere near.”
Struck has a list of plants that are not affected by the toxins. “More things can live by them than can’t. Mums, bleeding hearts, lilacs are fine near walnut trees,” he said.
"Some nurseries that specialize in native-type plants do sell black walnut trees," Struck said. Minnesota Extension Service considers Juglans nigra — the specific name of the black walnut — the hardiest of Minnesota’s walnut varieties.
“Older, river towns have lots of black walnuts,” Struck said. “Settlers just went out in the woods and dug one up when they needed a tree.”
When Mankato’s leaf curbside collection starts later this month, Street Superintendent Jim Braunshausen’s department will use a street vacuum to suck up any walnuts left behind by squirrels.
“We mix them in with the volume of leaves. They are stockpiled until they rot, then used as compost in our city parks,” Braunshausen said.