July 24, 2003

Hortiscope

Ronald C. Smith, Horticulturist
NDSU Extension Service

Q: I planted petunias and zanias in an outdoor bed and planters. This year the plants started to turn yellow at the outside of the leaf and then into the main steam. I also have several small violas that turned yellow and then brown. I use only rainwater with no fertilizer. These plants were blooming well and healthy looking until just recently. (Bison S.D.)

A: It could be a simple fertilizer need. Give the plants a shot or two of Miracle Gro or something similar a couple of times during the growing season. While rainwater is excellent for watering, if the soil is devoid of nutrients they are not going to thrive.

Q: We would like to know what a Juneberry bush is. How tall does it grow and what are its bushing habits? Is the fruit good for eating, making jelly or jam or feeding birds? (Forman, N.D.)

A: Juneberries are native to our region and are beautiful shrubs with white flowers in early spring and blueberry type fruit about this time of year. If you can get to them, they make good pies, jams and jellies but birds gobble most up before we humans can get to them. They also have a nice yellow/orange fall color.

Q: I have an Iris bed that is getting very dense. Can I divide the bulbs now or should I wait until fall? (E-mail reference)

A: It’s best to do it late summer or early fall.

Q: Can you tell me how to stop the suckers from growing on my crab apple tree? I cut them off each spring and they keep coming back. (E-mail reference)

A: Visit a local garden center or nursery and ask for "Sucker Stopper." Spray it on after you cut the suckers back. That should take care of them for the growing season.

Q: I have an individual who has seeded a new lawn using fairway-crested seed with oats mixed in. She wants to cover it with straw and is looking for guidelines as far as depth or any other information you can provide. (Hettinger, N.D.)

A: I would encourage her not to mulch, as it will only add more weed seeds. The oats she used will act as living mulch, which is much better. The oats will pop up and grow within a few days followed not long after by the wheatgrass. Tell her to begin mowing as soon as the oats reach four inches in height.

Q: I have some gardeners that called me about their cabbage plant leaves curling. They were planted before May 20. They have not noticed any insect damage or feeding. The plants have been exposed to pesticides. They said it is not happening to all of the plants. Is it safe to assume that pesticides are causing the leaves to curl? (Carson, N.D.)

A: It probably is the pesticide. The pesticide I am thinking of is some form of herbicide that was either an off-label or they may have over used the right stuff.

Q: I have a 7-year-old Colorado spruce that started to turn brown in the inside a year ago but the needles, for the most part, stayed on the branches. Now it's spreading to the next tree plus this spring a number of my pines began losing their new growth on the tips. They turn brown and fall off. Would spraying with Malathion take care of both problems? (Onaka, S.D.)

A: The first thing is to get the malady correctly diagnosed. Spraying with an insecticide will not help if the problem is a disease. Contact the South Dakota State University Extension Plant Pathology lab and send a sample to Marty Drapper for diagnosis. Describe to him, as accurately as possible, what you see happening.

Q: I understand that one should avoid trimming a crab apple in June or July. I have a tree trunk that did not get leaves this year. Should I trim it now or wait until winter? Also, is this dead trunk a sign of things to come for the rest of the tree? (E-mail reference)

A: Try to avoid pruning apples or crabapples in the hot, sticky months of summer to avoid possible disease problems but if the branch is dead, it isn't a good idea to keep it around either. I would recommend cutting it back to just outside the collar. This is not necessarily a sign of things to come. It could be the branch died of a cankerous fungus or borers that may have decided to take up residency in your tree. Monitor the condition of the tree and try to catch any anomalies that may show up early so they don't become a lethal threat to your tree.

Q: The grackles have nearly ruined my marigolds. They peck away and leave flowers all over the ground and sidewalk. Any ideas on how to make these pests leave my marigolds alone? (Fargo, N.D.)

A: Grackles are the mischievous teenagers of the bird world. Spray your plants with pepper spray. Also, tie aluminum strips to small stakes throughout your marigold planting. The pepper will burn their tongues and the aluminum strips will scare them. Once they are driven away they usually won’t return.

Q: A young lady brought me an egg shaped white thing that was growing from the base of a tree. It is not a mushroom but is shaped like an egg. It is rather soft and about an inch and a half long and about an inch in diameter. It appears it grew out of some kind of sheath as there is dried up sheathing around the base. (Lisbon, N.D.)

A: While not a mushroom, it is a member of the family. They are unromantically referred to as "conks." They are an indication of internal rot taking place in the tree. The tree owner should get an arborist to take an increment boring of the tree to see how far along the rot has advanced. The tree may need to be removed immediately to prevent property damage or personal injury.

Q: I looked at a yard where a large tree had been removed years ago. The dirt was also removed and large raised beds were put in using new dirt. Even with all that work they still have mushroom problems. The mushrooms come up in large four to eight inch clusters and push everything out of their way. It appears as though they are spreading but we have had a wet spring. (Hettinger, N.D.)

A: People can practice their golf swing on emerging mushrooms if they wish. Some people claim a 10 percent solution of bleach poured on the areas where the mushrooms are originating from will work. I don't like that idea too much because, at best, it has only a temporary effect. I don't like putting even a 10 percent solution into the environment. Mushroom growth will be the worst right after frequent rains but will disappear when we have drier and hotter weather.

Q: I have a 5-year-old hawthorn. This year, three quarters of the bark has come off the trunk and the leaves are very small. Can this tree be saved? (E-mail reference)

A: It doesn't sound like it. Once the damage is that extensive, it is usually only a question of time before the tree dies.

Q: I have white clover taking over my lawn. What can I do to control it? (E-mail reference)

A: Spray it with a herbicide known as "Clover & Chickweed Killer" or Trimec. You also need to fertilize your lawn. Clover invasion is a pretty good sign of insufficient nutrient levels, especially nitrogen.

Q: I was recently given a dying ficus tree. I repotted it and gave it tender loving care. The tree thrived but after six months I noticed leaves were starting to drop off. The dead leaves are a mottled yellow. I also found a drop of gummy white substance on the stem. I love this tree and don't want to lose it. (E-mail reference)

A: The gummy white substance on the stem is an insect that is feeding on the plant. It could be aphids, spittlebugs or scale. If you look closely you will likely see many of them, concentrated around the leaf petiole attachment to the stem. If the number is not overwhelming, you can remove them effectively with a cotton swab dipped in rubbing alcohol. If there are too many for that operation, then you will need to apply a systemic insecticide such as Orthene. This should be applied outdoors, not inside the house. After drying overnight, the plant can be brought back inside.

Q: I have an ornamental crabapple that I planted a few weeks ago. I have noticed that the leaves are always folded inwards. Could this mean the tree is over or under watered? (E-mail reference)

A: The first thing I would suggest is to look inside the folded leaf and see if there is a critter there. Some insect larvae will make a cocoon that way. It could also be responding to high temperatures as a means of conserving water. Many times the symptoms of over or under watering are exactly the same. That is a determination you will have to make. Most people tend to overwater.

Q: I am having a problem with several spruce trees. They are developing brown needles in some cases while others are developing bare spots where the needles have dropped off. Someone told me it is natural for spruce trees to lose needles and that they would be replaced. However two trees, both about 10 feet tall, lost all their needles and died. I have two trees that are about 40 feet tall and about 25 years old that are looking quite rough with sparse needle coverage. I have used a water-soluble fertilizer that is recommended for acid loving plants like azaleas and evergreens which I applied using a hose. They are in various locations in my yard and receive varying amounts of sunlight. (Eureka, S.D.)

A: Some needle drop is normal but a bare branch on an evergreen will always be a bare branch, it will not grow new needles. It sounds like you are dealing with a needle cast disease. Purchase some Bravo (chlorothalonil) to spray on the trees and do it as soon as possible. Spray again next year in June and again in July. This will help to control the disease. In the mean time, try not to spray the trees with irrigation water. That will only cause splash spreading of the disease organism resulting in further tree decline. If you want to fertilize, use Miracle Gro around the tree, spraying it into the root zone and not on the foliage.

Do you have a gardening or houseplant question? Write to Hortiscope, Box 5051, NDSU Extension Service, Fargo, ND 58105 or e-mail to Ron Smith at ronsmith@ndsuext.nodak.edu. Note to e-mail correspondents: please identify your location (city and state) for most accurate recommendations.

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Source: Ron Smith, (701) 231-8161, ronsmith@ndsuext.nodak.edu
Editor: Rich Mattern, (701) 231-6136, richard.mattern@ndsu.nodak.edu