Don Kinzler, Published August 13 2010
Fighting soil’s pH level is a losing battleQ: I just purchased a house in Grand Forks that I want to begin landscaping. The soil is gumbo and has a pH of 7.5. One of the plants I want to establish is a rugosa rose (snow pavement). While I love this rose, it is a battle to maintain green foliage. I am growing the rose in an area I mounded up by mixing in copious amounts of peat moss. Even so, I am putting on a liquid iron and various sulfate blends to keep the leaves from yellowing. Sometimes I lag or forget so the new growth is light green or yellowish. Can rugosas be grown as green- leaved, healthy plants in gumbo soil? Should I amend the soil? Should I plan on adding liquid iron or acid-based fertilizers and supplements? If I amend the soil, do I use peat moss or real peat? Should I incorporate the peat or pile the peat on top of the gumbo? Any other tips? (Grand Forks)
A: Fighting a pH level is a losing battle because our subsoil is so calcareous in nature. You would have to excavate the soil completely and plant the rose in pure sphagnum peat and sandy loam soil. After that, you probably would have to add chelated iron and sulfur-based fertilizers. My wife and I have done it in our garden. It is a lot of work, but it has given us the drainage and pH that we can work with. We add fresh sphagnum peat to the garden every year and work it in completely. In your case, once you got the soil worked up with all the needed amendments, you should be able to annually mulch some peat to keep the peat level acceptable.
Q: I took two cuttings from a white lace cap hydrangea. Both flourished and are blooming this year, but the flowers are pale pink. I understand the different color could be because of the soil. Will you clarify this for me? (e-mail reference)
A: There is no rational explanation that I can give you unless an identity or selection mistake was made. Cuttings taken from a plant are genetically exactly the same as the parent plant and will have the same foliage and flowering characteristics as the original stock.
Q: I live in western North Carolina. I have not dug my gladiolas up in seven years. Until last year, I had lots of colors. This year, every one of my plants is blooming a salmon color. Is that because they have reverted back to their natural color? I have noticed that all the wild gladiolas along the forest roads also are a salmon color. Is there a way to get the colors back? If I dig them up this year, will they go back to their colors? (e-mail reference)
A: No, they will not go back to their colors if you dig them up. If you want the variety of colors again, you have to start new.
Q: I am getting frustrated during my first year of growing corn. All of my plants seemed to be doing well, but then I found an infestation of earwigs. The bugs were eating on the tassels. Even though I have some tassels that are pollinating, I have no silks at all. Might the earwigs have destroyed all the silk? Should I pull it all up and start over next year? (e-mail reference)
A: Welcome to the club. It looks like the garden corn crop is going to be a hit- and-miss proposition this year. You can blame most of the problems on the weather and the insects and diseases that come with it. If there is no silk, pull out the stalks and start fresh next year. Sorry!
Q: We purchased a burlap ball north woods maple three years ago. During the first summer, it had a growth surge that resulted in a 2-foot by 3-inch long split down to the inner trunk. It continues to grow vigorously, but I am concerned with the long-term prospects of the tree. Do you have any suggestions?
Should I wrap the bad area in burlap? (St. Paul)
A: Burlap wrapping the trunk during the winter months until the tree develops a mature, corky bark is a good idea.
Q: We have an older maple tree that has shed bark since we moved here to southwestern Pennsylvania five years ago. I was able to peel the bark off the tree a couple of years ago because most of it had separated from the tree. This year, only sparse foliage has emerged and most of the leaves have brown spots.
What is this problem and can it be remedied? (e-mail reference)
A: The loose bark has no link to the dying tree. Contact a Pennsylvania State University Extension horticulturist in your county to see if an agent can assist you by physically examining the tree or getting a sample sent to the PSU plant diagnostic clinic. Failing that, you might consider contacting an International Society of Arboriculture certified arborist to inspect the tree for possible treatment or removal. Go to www.treesaregood.
CareService.aspx to get a listing of arborists in your area. Be sure to check credentials before allowing any major work to be carried out.
Q: I seeded my lawn this spring and fertilized it with 20-10-10 immediately after seeding. Everything looked great in the beginning. The grass was lush and green but then it started turning yellow in spots. I put the same fertilizer on again about four to five weeks ago to green things up. However, my backyard is yellowing again and grows much slower than the front and side yards. The front and side yards have thick, green grass. Most of the backyard is quite sloped and faces west. The backyard grass gets full sun from 10 a.m. on. Should I be fertilizing those yellow spots right away? If so, at what rate and what percentages of NPK? Can I apply Trimec at the lowest rate to control my weeds? (e-mail reference)
A: You can apply Trimec right now, but at the lowest rate recommended. As for the yellow spots, are you sure that it isn’t rust that is showing up? Brush your hand over the yellow area and see if any spores are picked or kicked up. If not, then this is likely a symptom of an immature or underdeveloped root system. The problem should clear up through time. I wouldn’t advise fertilizing again until this fall. Use what is marketed as a winterizer fertilizer.
Q: Every year my dad uses petunias for the major colors in his flowerbeds. We have had a problem around this time of year when the petunias turn into woody sticks, the leaves start to yellow and the plant stops blooming. We’ve been through the overhead watering, the soil with peat and sand, fertilizing and checking for disease or fungus problems. We can’t figure out what is going on.
Can you make any suggestions? (e-mail reference)
A: This sounds like a severe case of tobacco mosaic virus. It is transmitted by leafhoppers. Unfortunately, once the plant becomes infected, it continues to decline until the plant is dead. I would suggest that your dad consider using another showy bedding plant, such as geraniums, next year. They are competitive with petunias for color and will break the cycle of using the same plant family each year.
Q: I would like to know if there is any way to prevent or lessen the flowering of my little leaf linden. It has become the messiest tree in my yard. It is just off my patio area. I heard of Sevin working on crab apple trees. Would Sevin work on the linden? (Grand Forks)
A: I never have heard of it being effective on linden trees. Sevin’s reputation for reducing crab apple fruit is exaggerated. It is more often the luck of timing and a hit-and-miss proposition based on the cultivar. You can give it a try next spring if you wish. Keep in mind that lindens attract a lot of honeybees, so your timing would have to be when the bees aren’t active.
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 e-mail firstname.lastname@example.org.