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Don Kinzler, Published October 25 2012

Hortiscope: Insects cause of sap issue

Q: We have an old silver maple tree that we have trimmed three times in the past 15 years. The most recent trimming took place earlier this year.

This summer, I noticed a lot of sap all over everything on my deck, which is underneath the tree. My husband says he’s seen it do this before, but I have not noticed it before and I am out on the deck more than he is.

Last month, when I attempted to go out there and eat breakfast, I could see the sap falling in the air. Is this normal? If so, for how long will it last? Could it have something to do with the way the tree was trimmed?

The tree did look terrible after it was trimmed by a professional company. Any help would be most appreciated. (email)

A: Unfortunately, you are dealing with two issues. When selecting a tree care service, find an International Society of Arboriculture certified arborist or company. The standards are set pretty high to assure competent, safe and proper pruning.

A tree never should look awful after a proper pruning job. Usually, sap flow from pruning wounds occurs when the trees are pruned while dormant. However, it does not harm the tree. Generally, bleeder trees, such as maples, elms and birches, are best pruned after the foliage has fully expanded. This will reduce or eliminate any of the sap flow concerns.

The sap you and your husband are experiencing is the result of insect feeding activity. Aphids and/or scale insects eat the sap as a food source and then pass it through their bodies. A high population of these insects can make a sticky mess of everything under and around the canopy of a tree.

This and other insect feeding activity can be controlled by using a systemic insecticide such as Imidacloprid, which is found in Bayer and other products. If you see the name “Merit” on the label, it refers to the same insecticide. Follow label directions and apply the product early in the spring while the sap flow is at its highest.

If done properly, your insect and sap problems will be over for at least a year.

Q: As a new homeowner in McKenzie County, can I plant the lawn this fall? I am worried about the topsoil blowing. (email)

A: Oats are a quick cover that you could use because they will pop up in a few days. If the oats can get a little growth before freeze-up, they will stabilize the soil somewhat.

If you have an individual or company that does hydromulching in your area, you could have that person or company throw some oat seeds into a tank and spray them over the intended lawn area. The combination of the oats sprouting and tackiness of the mulch should stabilize the soil against even the most severe wind forces.

The oat plants will be killed by hard frosts, so they will not be a permanent part of the lawn next year, but they will add valuable organic matter.

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.

For answers to general horticultural questions, go to http://www.ag.ndsu.edu/horticulture.

Q: Would you please share your knowledge about Asian beetles? It is my understanding that they were imported by the Food and Drug Administration for the purpose of combating aphids in soybean crops. We live in a heavily forested area 15 miles from the nearest soybean crop, but we are inundated with these nasty little critters. However, the people who live across the road the from bean fields have none. Does the FDA have any plans for controlling this bug or is this just another kudzu vine experiment gone wrong? (email reference)

A: Asian lady beetles are a tremendous benefit to farmers and the environment because insecticides don’t need to be used on the crop. While the crop flourishes, the beetles are feasting on the aphids. Once the harvest is over and the weather cools, these critters look elsewhere for food and comfort. Your property being inundated is by random chance. Very likely they won’t be as bad in future years. The beetles are annoying to us humans, but their benefits far outweigh any shortcomings they have.

Q: I have spent the last two days reading your posts about jade plants only to learn that I may have killed my entire family of them. Until now, I have had tremendous success at growing jades because I leave them alone. I have had the “grandma” for more than 15 years. The plant has been moved from Missouri to Florida and now back to Missouri. The past four years, this old plant and the multitude of offspring she has produced have lived outside on my deck in full sun. They were flowering recently and doing great. Recently, I pruned, repotted and added some lava rock to the bottom of the pots to make them more manageable because of the weight. I brought them in the house because we are supposed to have some frost. If I haven’t killed the plants by repotting at this time of year and adding the rock to the bottom of the pots (should have read your postings sooner), how do I manage the light difference by moving them inside? My rooms get full, indirect light. After being in full sun for so long, I am concerned that the stress of being pruned, repotted and moved indoors is going to kill the plants. Should I consider a plant light to help wean them off the direct light? If so, what kind and how long per day? I never have fertilized or used rooting food. Thank you for all the postings. I appreciate your time and expertise on this question. I am praying that I have not wiped out 15 years of love and beauty in one week! (email reference)

A: The consequences of going from full sun to low, indirect light usually are some leaf drop and the re-emergence of new foliage that is adapted to the newer conditions. This would take place through several weeks to a few months. Adding a plant light system would help level off the light intensity diet and reduce the stress on the plants. You can purchase these plant lights at many big-box stores. Set the timer for the light to be on 14 to 16 hours and place it about 12 to 18 inches above the foliage. I think your worry is premature because it sounds like you are a pretty savvy houseplant gardener. All the plants should survive at their new location.

Q: I love buckeye trees but cannot find where to buy them. The type I am interested in is the aesculus glabra. There is one at an abandoned farm that we rent. However, it can’t be moved. What type of soil does a buckeye tree do well in? Thank you so much for your time and advice beforehand. (North Dakota)

A: Why not just collect some buckeye nuts from a tree and plant them? That would be the easiest and least expensive route to take. If you can visit a good garden center in one of the major cities of Bismarck, Minot, Grand Forks or Fargo, it should have or can get one of the better cultivars of aesculus glabra.

Q: My orange tree has done well outdoors this summer here in hot Milwaukee. However, it had a lot of flies on it for the past month. I moved it in to my sun porch and noted many of the leaves are sticky. I cleaned each leaf off twice with soapy water, but the sticky stuff came back. I also sprayed it with rubbing alcohol, but it didn’t help. What can I do? (email reference)

A: This could be from scale insects infesting your tree. The fact that flies were attracted to the tree is an indication that there was a feeding insect population somewhere, but not on the foliage, because you’ve carefully wiped the leaves down twice. Look on the stem to see if there are any lumps along the branches. I’m willing to bet that this is the cause of your problem. Because this is an ornamental tree and not one for consuming fruit, I suggest visiting a local nursery or garden center to see if it has a systemic insecticide available for controlling scale insects. Apply the product according to label directions and your problem will end eventually.

Q: Is it safe to eat potatoes that have green patches on them? I always thought this was from exposure to the sun, but many of my Yukon gold potatoes had this problem even though they were several inches under the soil. (email reference)

A: The green coloration is from the chlorophyll that manifests itself in the skin from exposure to light. As annoying as this is, if it is just a patch or two, you can cut that out and still consume the potato. I’d also suggest storing them in a light-proof location, such as a pantry or paper bag, to get them back to the nongreen manifestation. Don’t put the potatoes in the vegetable crisper in the refrigerator because that tends to sweeten them to the extent that their taste is altered. Some folks don’t mind that characteristic, but I’ve found that potatoes will fare better if kept in a cool room and in the dark.

Q: I have a spider plant that my grandmother gave me in 1996. The plant never produced flowers or very many babies until I moved more than a year ago. The plant now is exploding with growth. Right now, I have 20 cuttings that seem to be growing well. Before that, I had 45 new cuttings growing in two weeks. However, none of the cuttings I’ve grown have produced any inflorescence (group or cluster of flowers). Is there anything that would encourage inflorescence growth? The plants are extremely healthy and have the proper nutrients, so I’m not sure if it’s just something that will come with time. Any suggestions would be appreciated. (email reference)

A: These plants seem to thrive and produce well on a little benign neglect. Allow them to become almost obnoxiously pot-bound and don’t fertilize. Set them out in the summer months in dappled shade and exposed to the harshness of the natural environment. Bring them in just before a killing frost. That should push them into their reproductive cycle. It has worked for me for the past two dozen or so years.

Q: I appreciate the information on your website because it has helped me refine my questions. I just took out an old five-stem white bark clump birch from our front yard. It was beautiful in shape and color until about half of it died this year. In addition, it dropped many tiny seeds that got tracked into the house. I want to replace it but don’t have much room. The chosen spot has a concrete driveway 8 feet away to the east, sidewalk 8 feet to the south and our waterline another 6 feet away on the west. We liked the very angular trunks of the birch and we pruned the branches enough to mow under it. Can I prune or train a ginnala flame maple to a similar shape? Does the maple have a shallow enough root system that it will not attack the waterline? When do the seeds or fruits fall? Alternatively, is there a seedless clump birch I could plant? (Salt Lake City, Utah)

A: Birch species are monecious, which means that both sexes are on the same tree. The maple of your interest should pose no problems to your waterlines. The roots will be attracted to the waterline only if it starts leaking and water reaches the roots. I have had one in my backyard for 27 years. It is going strong and looking great. Knowing the Salt Lake City environment as much as I do, I encourage you to make the maple your choice. Thanks for the nice comments about the website.

Q: Can I fertilize my lawn this late into October? Will it do any good to apply a weed killer at this time of the year? Thanks for your help. (email reference)

A: Fertilizer can be applied if the ground is not frozen. As for using herbicides for weed control, if you live in North Dakota, applying any herbicide at this late date would be futile and result in poor control. It needs to be applied when the weeds are in active growth, which is somewhere around the Labor Day holiday. With rain very much lacking this summer, the lawn weeds were pretty much shut down. A homeowner would have had to spend about a week of conscientious watering to soften the weeds enough for them to be receptive to herbicide applications.