Dishing the Dirt

Dishing the Dirt SHERBURNE COUNTY MASTER GARDENERS NOVEMBER 2020 From the Potting Shed… IN THIS ISSUE Well, that was different. If you are like me, the snow and Potting Shed 1 cold that descended upon us in the second half of October Too Good to be True 1 were unexpected. If you are like me, you were caught off Weed of the Month 5 guard and didn’t have all of your fall clean up chores done. What’s Coming Up 6 And if you are like me, you used the warm days of early November to quickly catch up. Autumn’s weather has not been cooperative for those of us scrambling to finish larger outdoor projects, or at least make them winter ready so that we can start up again in the spring. If you still have leaves to rake, you are not alone. Despite the snow, this is still a good time to work on buckthorn. What else are you going CONNECT WITH to do this time of year? This month is the second in a two-part series about the nasty stuff. US! Last month, we learned why it is such a threat and how to identify it. This month, we learn about how to get rid of it. I have several acres and it’s everywhere on my property so I can Horticulture Hotline: relate to those of you who battle to remove it. 763.765.3080 Just because your gardens are hibernating for the winter doesn’t mean you should too. There are lots of learning opportunities online, virtual garden tours, and you probably Email: mnext- have a gardening book or two that you want to read. This is a great time to educate [email protected] yourself about your favorite flower or veg, a troublesome weed, or better soil. Extension Office: Get gardening and get growing, 763.765.3075 The Sherburne County Master Gardeners Website: www.sherburnecounty mastergardeners.org/ Facebook: Click Image! Too Good to be True - Part 2 By Brigette Gatzke Now that you know how to identify buckthorn, what do you do about it? More importantly, how do you get rid of it? The Minnesota Department of Agriculture classifies buckthorn as a Restricted Noxious Weed meaning the plants are so widespread that Editor: Brigette Gatzke elimination is not realistic. However, in order to prevent further spread it cannot be Sherburne County imported, sold, or transported. If you have it and want to get rid of it, or at least bring it to Master Gardener a manageable level you must accept that this will be an ongoing battle. Buckthorn is tough to get rid of once established and requires patience and persistence. UNIVERSITY OF MINNESOTA EXTENSION PAGE 2 OF 6 DISHING THE DIRT – SHERBURNE COUNTY – OCTOBER 2020 Buckthorn’s Strategies Why is it so difficult to remove? It uses three main strategies to persist in the environment and you will need to address all three in order to get rid of it. Super seeds - The berries contain many seeds, the seeds have a high rate of germination, are unaffected by digestive systems of wildlife and birds and finally they remain viable for years. Allelopathy – A large female tree (remember there are male and female plants) will exude a chemical so even other buckthorn seeds will not germinate; when the female tree is cut down, all those seeds germinate. This chemical also prevents other plants such as natives, from growing around the buckthorn. Resilience – The plants re-sprout after cutting if the stump is exposed to sunlight allowing photosynthesis to occur. The cut stump must be covered or treated with an herbicide. Your Strategies Adjust your expectations - This will be a multi-year effort that requires hard work. If there is buckthorn in the area, then as long as birds fly, buckthorn will appear in your yard. Sometimes the best hope is to keep it at a manageable level instead of complete elimination. Manage seed production – Cut down the large female trees (called queens by buckthorn warriors) first, then smaller females, then the males; this should cut into seed production and reduce the number of new plants. Manage seedlings - After cutting down a large queen, follow up several times that year and subsequent years to eradicate the seedlings, either by removing them or spraying with an herbicide. Look for seedlings in other places where birds perch such as tree rings, power lines, and fence lines. Hand pull or spray these when they are small before they can get established. Remove established plants – Smaller plants can be either dug or cut with loppers or hand saws; larger plants will need to be cut down with hand saws or chainsaws. The stumps need to be handled properly to prevent them from re-sprouting and creating what buckthorn warriors call a Medusa which is even harder to remove. Digging – The one weakness, if it can be called that, is that the root system is shallow. It’s fibrous and extensive but relatively shallow and bends off to the side of the tree, looking much like a hockey stick or the letter “L”. The roots can be loosened with a shovel or spading fork and the tree pulled out. Sapling pullers can also be used. Inquiries with other buckthorn warriors found mixed reviews. Some loved them and some thought they were ineffective. I found a sapling puller difficult to use in loose, sandy soils, but easier in more firm soils. Digging disturbs the soil potentially bringing more seeds to the surface so continuous follow up will be required. Cutting – Loppers, hand saws and chainsaws are all used to cut buckthorn, depending on the size of the tree. Regardless of how it is cut, the stump needs to be treated with an herbicide or covered to prevent re-sprouting. o Herbicides – The cut stump needs to be treated quickly (preferably within an hour) before it dries and seals otherwise the herbicide will be ineffective. Regular herbicides are not strong enough, use one labeled for “tree and brush” removal which has a stronger percentage of the active ingredient. The two active ingredients most effective against buckthorn are glyphosate and triclopyr. Always read and follow the directions on the label of any herbicide. UNIVERSITY OF MINNESOTA EXTENSION PAGE 3 OF 6 DISHING THE DIRT – SHERBURNE COUNTY – OCTOBER 2020 o Covering the Stump – If you are averse to herbicides or you want to double down on your elimination strategies, covering the stump keeps the sunlight off of the stump. Stumps can be covered with tin cans, black plastic baggies or sheets of black plastic. Reusing tin cans is inexpensive. Experts recommend nailing from both the top and the side to prevent them from coming loose. I use double-headed nails for easy removal later and I’ve been known to spray paint the cans with brightly colored paint to find them more easily. Black plastic baggies can be zip tied into place (available on the internet). For a small area without other trees or plants, a heavy black plastic sheet on the entire area (weighted around the perimeter) prevents re- sprouting. Regardless of how the stumps are covered, they need to remain covered for at least one year. Commercial removal – There are any number of companies that will gladly come in and remove buckthorn for a fee. This can be expensive depending on the level of infestation. Animal assisted removal – There are a few companies that use goats and pigs to remove buckthorn by allowing the animals to eat all the plants, including the roots. This too can be expensive, and some indicate it can also be messy. Disposal Now that you’ve dug it up or cut it down, what do you do with the stuff? Minnesota laws make it illegal to put noxious weeds in a trash bin. They prefer the plants be destroyed on site to prevent further spread. If you have a larger property an area can be set aside where the buckthorn can be piled up and decay naturally. This would be separate from any compost pile used to amend the soil. Follow up for seedlings will be required in this area. I know one person who is shredding buckthorn into mulch. I have doubts about this idea since any berries/seeds that get into the mulch would germinate when the mulch is spread. If you have a yard waste pickup or a community yard waste disposal site, check with their regulations; some will take buckthorn, and some will not. Personally, I and other buckthorn warriors, find buckthorn bonfires extremely satisfying. Something Positive Are there any bright spots in this nightmare of a plant? First, the allelopathic chemical in buckthorn is not the same as black walnut and does not linger in the soil for very long. Once buckthorn is removed, natives re- emerge quickly. Replanting with natives also helps to discourage it from coming back. The Soil and Water Conservation District has information and programs for re-establishing native understory plants. Second, I have found several woodworkers who claim the grain of buckthorn wood is rather pretty and easy to work. One of our Master Gardener guest speakers was a woodworker who made wooden spoons and cribbage boards. I’ve seen trinket boxes and turned candle sticks as well. My other half includes woodworking as a hobby and currently has several larger sections of tree trunks drying out for future use. He’s also interested in log furniture so there is a joke about buckthorn barstools for my kitchen counter. I’ll let you know how that goes.

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