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Published December 09, 2011, 12:00 AM

Hortiscope: Freezing walnuts makes cracking easier

Q: I have a question about black walnuts. We get plenty of black walnuts from our trees, but I’ve never thought much about using them. I always let the squirrels have them. This year, I wanted to make a black walnut pound cake. Do I wash the shells and let them dry or just lay them out and let them dry before I crack open the shells?

By: Don Kinzler, INFORUM

Q: I have a question about black walnuts. We get plenty of black walnuts from our trees, but I’ve never thought much about using them. I always let the squirrels have them. This year, I wanted to make a black walnut pound cake. Do I wash the shells and let them dry or just lay them out and let them dry before I crack open the shells? I saw the article about putting them in the freezer for 72 hours and then putting them in a vice to open the shells. Does the freezer idea work? I am glad I ran across your website while looking for help on how to crack open the nuts. (email reference)


A: With black walnuts, working with clean nuts is a must. Rinse them well and allow drying. Keep the shells away from any possible poaching by squirrels. When you get ready to crack them, the freezer treatment makes the shell easier to break in a vise or with a good pair of channel locks. The extracted nutmeat should be used as soon as possible after opening to prevent it from becoming rancid. Go to http://goo.gl/0VLwO to find a nutcracker that will take the misery out of cracking open these impossibly hard shells. If you really are intending to do any quantity through the years, this machine or a similar one would make this an enjoyable task. You probably won’t want to spend the money, but I’m willing to bet that before you get 50 nuts cracked, you’ll either decide to leave them for the squirrels or go ahead and make the purchase.


Q: I have a friend who believes he has a crab apple tree. It is 7 to 8 inches tall. He wants to know if he should keep it inside for the winter and how to prepare it for storage. Instead, should he plant it outside right now? I don’t want to tell him the wrong answer, so I told him I would send you an email. I told him you are very experienced and know everything about horticulture, so we can’t go wrong with asking you. Thank you. (Lake Andes, S.D.)

A: Such flattery. I wish it were true, but we both know that isn’t the real story. I provide the best research-based advice from what I know and can find.

After that, I hope for the best. Your friend is better off leaving the seedling to where it is for the winter. It needs protection from voles and rabbits, so surround the seedling with hardware cloth and chicken wire to protect it from these varmints. Next spring before it leafs out, dig the seedling out and move it to where he wants it to grow. Water it in well.


Q: I have seen conflicting reports on whether a green ash qualifies as a weed. I realize they are very fast-growing trees. Does this fact qualify them as weeds?

They make nice shade trees. (email reference)

A: Let me put the conflict to rest. A green ash is not a weed. Horticulturists have been recommending growing green ash trees for decades because of their relative ease in getting established and tolerance to a wide variety of ills.

However, green ash is susceptible to emerald ash borer. If you are in a region of the country where this pest is doing its nasty best to eliminate the ash trees from our ecosystem, then I wouldn’t recommend planting green ash trees. If you are well outside the area, such as another state or two away from the closest infestation, then the decision is yours. Some folks are betting the research to control this pest is not going to result in fruition soon enough for them and are taking out their ash trees and replanting with another species.


Q: I live in Wisconsin and have a hibiscus plant that I purchased in the spring.

It did great all summer. However, the last couple of months, almost all the branches and stems have lost their leaves. Only one stem still has leaves. I am not sure if I should get rid of the dead branches and repot the plant or leave it and keep doing what I have been doing. I have it next to a window, so it receives as much sunlight as possible. Thank you for any help you can share with me. (email reference)

A: First thing to do is to scrape some of the bark tissue back with your thumbnail to see if any of the leafless branches are alive. If so, then you have little to worry about except how it looks. That can be corrected somewhat by cutting those branches back to about 4 to 6-inch stubs. Make the cuts just above the buds. If the branches don’t show green beneath the thumbnail scratch, then something has or is killing the plant, so you might be better off dumping it. For information on hibiscus care and problems, go to http://goo.gl/UAbvc. Review what is there to determine what is going on with your plant. It sounds like you’ve been doing the right things.


Q: I’ve had a croton for nearly 25 years. I saved it once in the very beginning by pulling out some sort of bugs in the dirt before the last leaf fell. After that, it grew tremendously. My problem is that we left it outside too long. My husband and I are very concerned we may lose it after all this time. The leaves are drooping, but they are mostly still soft and green, with the exception of a few that have turned brown. It’s been indoors for two days with no signs of change. Is it too late? Thanks for any help. (email reference)

A: It all depends on where you live. If it is North Dakota or one of the surrounding states up north, then it is dead. If your area only has had a light frost and the plant was not hit directly by it, then it received chilling damage and should recover with normal care. Do not overwater or fertilize the croton.

Allow nature to take its course and eventually new growth will emerge. It is not going to happen overnight and the plant will look ugly for some time, so you need a little patience.


Q: I was just talking with a gentleman who is concerned about needle cast on an evergreen. What treatment options would he have for this tree? Thank you. (email reference)

A: Fungicides, such as chlorothalonil, can control this disease from spreading.

However, the timing is very critical. The evergreen should be treated twice a year for at least two years to get the disease under control. Try to have the client follow label directions for effective control. Now is not the time to do an application.


Q: My 5-year-old niece asked me to help her plant apple seeds. There now are two trees in a small container. The leaves have a powdery substance on them. I hope you can help me get rid of the substance because she gets so excited when something grows. I want to keep that excitement alive if I can. (email reference)

A: We never want to discourage enthusiasm when it comes to growing plants. Make sure the plants get plenty of bright light from sunlight coming through a window or from a plant light. The powdery substance probably is powdery mildew.

Generally, this affliction is not fatal to plants but can cause a slowdown in growth. Avoid getting water on the leaves and don’t overwater. Have a small fan blowing gently over the foliage through most of the daylight hours and remove the infected leaves. If all the leaves are showing symptoms, use a solution of baking soda in water (1/2 teaspoon in a quart of water) and gently wipe it over the foliage. If the cups or containers do not have good drainage, cut or somehow make holes in them to facilitate good drainage and prevent root rot.


Q: A lady has daisies that she planted this spring. She said they grew and bloomed beautifully. She would like to know how to care for them properly this fall. I looked through publications and on the Web but couldn’t find the specific answer. Can you help me out? (email reference)

A: I’m assuming they are the perennial daisy species that she planted. If so, then she has nothing to do except cut back the dead foliage this fall before winter closes in. She also can allow the daisies to remain to attract more snow accumulation and then cut them back in the spring. If they are annual daisies, then they already are toast and can be added to the compost pile.


Q: We live in Massachusetts and have a clump heritage river birch that we planted 13 years ago. During a recent storm, the top half of one of the main trunks split in half. Should we remove the remainder of that trunk down to the ground or cut it off where it broke? In either case, will the tree begin to fill in again? (email reference)

A: I envision this being a tear rather than a clean break. I would suggest removing the entire trunk because you don’t want to leave a large stub after pruning. Without seeing the situation you are addressing, I cannot say that it will fill in for sure. However, in all likelihood, it will from what I know of heritage river birch.


Q: I bought a tree several years ago that seems to be happy. However, it always turns yellow in the fall instead of red. Any ideas why this happens? (email reference)

A: The tree lacks the color pigment anthocyanin that develops the red foliage.

There is a direct cause and effect to this coloration problem. Low temperatures and bright sunshine destroy chlorophyll but enhance anthocyanin (pigment) production. Dry weather increases the sugar concentration in the sap and increases the amount of anthocyanin. This means the brightest autumn colors are produced when dry, sunny days are followed by cool, dry nights. High nitrogen inputs from turfgrass fertilization practices surrounding the tree will inhibit anthocyanin formation. I know you are not going to stop fertilizing your lawn, so I would suggest that you take a spade and drive it into the ground in about a half dozen places around the canopy edge of the tree. This may shock the tree into anthocyanin production next year. I also would recommend pulling the stone mulch away from the trunk of the tree to keep it from forming a girdling effect with the passage of time. Your tree would be better off with black soil or organic mulch.


To contact Ron Smith for answers to your questions, write to Ron Smith, NDSU Department of Plant Sciences, Dept. 7670, Box 6050, Fargo, ND 58108-6050 or email ronald.smith@ndsu.edu.

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