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Don Kinzler, Published March 16 2012

Hortiscope: Contact arborist before major tree cutting

Q: Your website is very useful. We live in the Adirondacks. There are about a dozen large pine trees beginning to impede our view of the mountains. I was thinking of cutting them down but I would prefer to trim the top 10 to 20 feet off. (email)

A: I strongly encourage you to contact an International Society of Arboriculture certified arborist and seek advice as to the best course of action to take in this situation. Go to http://tinyurl.com/

69fgll3 to locate the arborist nearest you. Be sure to check credentials and references before allowing any work to proceed.

Q: I am helping or trying to help our school. The school has a hot house that we have used for about a year. This year, we bought plugs to start for our plant sale. Some of the impatiens look very poor. They are wilted and do not look healthy. I am not sure if they have a fungus or if it is how they were planted.

I had several little hands helping me and I’m not sure if they gave the plugs the right amount of space. Any suggestions? Also, we are using a pellet fertilizer. Do you think we also should start a water-soluble fertilizer? (email)

A: It would be very difficult for me to give you accurate advice from the information you provided. I need to know if the plugs arrived already rooted.

Were they exposed to winter-cold temperatures for even a few seconds? When you potted the plants, what kind of potting media did you use? Was everything the plugs came in contact with sanitized? Were they immediately watered with tepid water? Cold water straight from the tap at this time of year can send tender plants into shock. How about light and air circulation or the temperature of the house? If you could send me a few photos with the above questions answered, I might be able to help. You could send a sample to the land-grant university in the state where you live (I have no clue where that is from your email).

Q: Last year, it looked like something kept eating my watermelons and cantaloupes in my garden. I would go to lift up a cantaloupe and something had eaten it from underneath. Any ideas what I can do? (email)

A: Plant these crops in a different location this year. If you are going to replant the same crops in the same location, bed the fruit on a layer of diatomaceous earth. Put about ½ inch around and under the developing fruit.

You also can grow the fruit on a trellis. It is done very successfully all the time. You have to give the fruit proper support, so make sure you are using a trellis that is strong enough to support the fruit during windy conditions. I don’t want to recommend insecticides because the whole purpose of backyard gardening is to avoid the use of pesticides. The damage likely was caused by grubs or beetle larvae.

Q: While removing some dead trees, I came across this critter in the sample I sent. Is this pest the culprit that could be causing my tree to decline? (email)

A: The sample you sent was identified as carpenter worm larvae by NDSU Extension Service entomologist Patrick Beauzay. The larvae are very destructive.

Unfortunately, systemic insecticides are not effective. Maintaining tree health is the most effective approach. The carpenter worm is a major pest of hardwood trees and first was described in 1818. Their lifecycle is two to four years, depending on geographic location. However, generations can overlap, so one may find larvae in all stages of development at any time and moths in flight every year. The moths emerge during daylight hours. Females usually emerge slightly earlier than males. Females produce a sex pheromone that attracts males. Females normally mate once, but males may mate four or more times. The eggs are laid in groups of two to six. The number of eggs laid in each group varies from 200 to 1,000. Eggs hatch in 10 to 14 days. Newly hatched larvae feed for a short time on the empty eggshells. However, within a few hours, they begin penetrating bark or entering openings. The number of larval instars (stages) varies from eight to 15. Young larvae feed on the inner bark until about half grown. Then they bore into the wood to make tunnels that angle upward in the sapwood and turn straight up in the heartwood. Tunnels are kept open and enlarged by the growing carpenter worms. Eventually the tunnels may reach a diameter of 5/8 inch and 12 inches long. Mature larvae line their tunnels with loose, silky, yellowish-brown webs. Pupation (17 to 19 days) occurs at the upper end of the tunnel. Mature pupae wiggle to the opening of the tunnel and protrude from the trunk. The adult soon emerges after that. The pupal skin remains protruding from the trunk until it weathers away. Little is known about any natural control of this insect. It is believed that predators, such as woodpeckers on the larvae and kingbirds on the adults, account for the destruction of fairly large numbers.

Because their flight period is so long, targeting adults with insecticides is impractical. Mechanical control (inserting a wire into the gallery to kill the larva) is feasible only if a few trees are affected. Because a pheromone is available, trapping or mating disruption may be possibilities, but they have not been proven as viable techniques. The best management strategy is prevention.

Winter or mechanically injured trees are more susceptible, so keeping trees healthy and vigorous will help prevent carpenter worms from becoming established.

Tree removal may be the best course for extensively damaged trees.

Q: I have a few questions. I am heading out today to buy a few houseplants to spice up my apartment. The windows face north and are unobstructed. What kind of houseplants can I buy that will thrive in these north windows? Some plants I have looked at are Bella palms, heart leaf philodendrons, Janet Craig compacta, bird nest snake plant, golden pothos and small flowered anthurium. I was told that peace lilies do not flower when placed in north-facing windows. I also was told that I need an east window to get any plants to flower and grow leaves. Is that true? Let me know what you would recommend. (email)

A: The north side terminology is misleading. It connotes low light to the extent that people translate it into meaning there is no natural light reaching the plant. You are describing bright, indirect, natural light. Some plants that will do well under the conditions you describe are the Aglaonema commutatum varelgans, Chamaedorea elegans, Dracaena deremensis ‘Janet Craig,’ Spathiphyllum ‘Clevelandii,’ Maranata leuconeura and Pothos aureus. There are many more. If any extended dark periods come up, keep in mind that plant lights can be added to intensify and extend the light periods.

Q: I’ve just found your website but I couldn’t find an answer to my problem. I’m hoping you can help. I was entrusted with the care of my neighbors’ jade plants while they were travelling. There was a problem with their furnace, so the house reached extreme temperatures for a few days. To make matters worse, one of the larger plants was located near a heating vent. As a result, the leaves have all shriveled. However, the stock appears firm. I watered them immediately (the incident took place a couple of weeks ago) but they still look the same. Will these plants survive the extreme temperatures they were subjected to? Any direction would be appreciated. (email)

A: Because one of the plants you mentioned was near a heating vent, I’m assuming that the furnace just kept running and cooked the plants. Survival is dependent on how long the plant was subjected to the extremely high temperatures, the condition of the plant prior to the event and if there were other mitigating factors contributing to the plant’s damage. Try to keep the soil moist, but don’t overwater. Keep the plants where they get good natural light or provide artificial light. Only time will tell if the plants will recover. It will take a long time.

If you have any correspondence with the owners, I’d suggest telling them before they come home just what happened. Baby-sitting someone’s house plants is risky. There is too much that can go wrong and the baby sitter gets the blame.

Q: I came across your website where you answered many questions about blue spruce trees. However, I could not relate any of the questions to my problem. I have many Colorado blue spruce trees on my property. I park a camper during the summer close to two of the spruce trees. I spend hours cleaning my camper because it appears the trees literally throw black specks over the entire camper. I assume this is sap because it is extremely difficult to get off. I figured the tree would do this once a year, but I guess I was wrong after cleaning the camper multiple times last summer. Is there anything I can do to the tree or should I just bite the bullet and move the camper somewhere else? (email)

A: Those black specks you are cleaning off the camper are insect poop. Aphids or some insect population is causing these spots to show up. Check your spruce trees carefully or send a sample to your land-grant university’s diagnostic lab to see if there are insects that have taken up residence. It could be that something has established itself on your trees that is not causing visible symptoms of decline or discoloration because of the vigor these trees possess.

It would be worth checking with the lab so that you can initiate some control before the problem gets too far along.


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.