Horticulture Guy

Q. I have a very small maple tree in my front yard, transplanted this spring from a shoot that sprang up in my flower bed! It was doing quite nicely; however, a recent windstorm broke a couple of its branches (and it only has a few!) Do I need to cut these broken branches back in order to help the tree, and if so, how? Or should I just leave it alone, trusting it will grow new branches in the spring? Judy Grover - Tacoma, WA

A. The “shoot” that appeared in your flowerbed was very likely a volunteer seed that flew in from a nearby maple.  Maple trees fruit/seed are called samaras.  They are the also called helicopters and “pinnochio noses” depending on how the children of the area play with them.  If you haven’t determined which maple you have I would first check around your yard or your neighbors yard to determine what kind of maple may have sent a seed into your flowerbed or have the maple identified by a professional. You were wise to move it to a new location since the sooner you find an area that can accommodate your maple tree the easier the transition will be for the seedling.  Just be sure your new location will accommodate the future size of your maple. You said some branches were broken in a windstorm.  It would probably be a good idea to trim back the broken branches to an existing bud on the branch and removing any jagged edges where diseases can take a foothold.  If what is left of the branch would not contribute to the structure of the tree as it grows then you can cut it back to the main trunk.  This is general information since it is difficult to give more specific advice without seeing the actual tree and the damage. 

Q. I want to plant a nice shade tree in my back yard. It seems like every tree I consider has its pros and cons. I am most concerned about the mess—I have installed a beautiful clay paver stone patio that we use like another room in the house. I love Oaks but I don’t want acorns all over the patio. I love Maples, but I don’t want those helicopter things falling either. A medium-fast grower would be great. I live in Minneapolis. (zone 4b, I think.) Any advice? THANKS! Mark Jacobson - Minneapolis, MN

A. I am inferring from your question (since you mentioned maples and oaks) that you want a deciduous tree that provides shade in the summer and then allows light during the winter.  So I assume that you are all right with leaf raking duty but just not dealing with a trees fruits/seeds.  Since fruit/seed comes from female flowers (or the female part of a complete flower) selecting a species of tree where the trees’ gender is split by individuals would be useful.  This setup in a plant is called dioecious (Greek for two houses).  So one tree has male flowers only and the other has female only.  Oak and Maple (as well as many other well known trees) are monoecious (you guessed it “one house”) so both flowers are present in each individual.  There can be either both male and female flowers on the plant or a complete flower that contains both the male and female parts (like a hermaphrodite). The Ginkgo (Ginkgo biloba) is a dioecious shade tree whose cultivars are asexually propagated (cloned) from male trees.  This has been propagated this way because the female fruit stinks to high heaven!  Another alternative is to find sterile trees that don’t produce fruit or seed like Marshall’s Seedless Green Ash (Fraxinus pennsylvanica) as well as many of the other ash hybrids that are seedless.  Now that you know to ask for male or sterile cultivars of shade trees you can also visit your local nursery to find out what selection is available to you locally.

Q. In our condominium complex we have several English oak trees. We had an arborist prune those plus another 40 trees of different species. The English Oaks are getting to be approximately 30 plus ft. tall. I hear that they may grow to 40 to 70 ft. tall. The arborist told us that they should not be topped. Some of the residents are complaining that they are afraid that they will become a hazard as they may blow down. What do you suggest we do?  Thank you, Donald Berglund - Lakewood, WA

A. I suggest you follow your certified arborist’s recommendations.  Topping is an outdated technique for attempting to reduce the size of trees. Just like most scientific based practical applications there have been many changes over the past few decades in arboriculture.  Research has shown that topping or “heading back” trees creates more problems than it solves.  It can even make a tree more hazardous.  The International Society of Arboriculture (ISA) credentializes certified arborist (through local chapters).  These individuals must also maintain continuing education credits, which keep them up to date on the latest science and techniques of their field.  If you are hiring a certified arborist to look after the health of your trees then you are reducing the hazard potential of these trees.  Tree height is more of an indication of how much damage a hazard tree can cause, not necessarily that they will be a hazard.  Any factor that diminishes the health of the trees will contribute to that trees hazard potential. For more information on why topping is bad you can see an article developed by the ISA called “Why Topping Hurts Trees”,  http://www.treesaregood.com/treecare/hazards.aspx.  There are some other great articles on this website for the homeowner as well that explain hazard trees.  

Q. I have a plant labeled as “mass cane.” I’ve noticed recently that most of the leaves are starting to turn yellow at the tips and eventually the yellow turns brown. I have not watered the plant for 2-3 weeks now for fear that it has been over watered. I’ve checked the soil and it seems as if at least the top half of the soil depth is mostly dry.  I bought distilled water for the plant because I’ve read that fluoride can cause yellowing in the leaves. So the last time I watered it I used the distilled water but that didn’t seem to help. The plant is in a bed room that has a window (mostly covered by a curtain to block direct sunlight) facing the south so the plant usually receives a decent amount of filtered light. Also about a week ago the plant fell but landed upright; there was no damage to the plant but the canes probably moved around a little  in the soil. What needs to be done to keep this plant healthy? Matthew Broten - Champlin, Minnesota

A.  You mass cane is a common name for Dracaena fragrans ‘Massangeana’ also called a Corn plant because of the shape of its leaves.  The variegated (with the light yellow/green stripe in the center) seem to need more light, perhaps because there is less chlorophyll on each leaf.  When I was working in indoor landscaping it seemed that I would need to trim the necrotic tips off of the plants that received the least amount of light.  Although they are tolerant of low light levels I always found that they did best with some direct light for part of the day. Of course the more light they receive the more water they require making it less likely that they will be overwatered.  Overwatering (as I suspect you know from your question) will suffocate the roots and kill them.  The symptoms are the same as underwatering because the plant itself is not receiving water. If the leaf tip symptoms showed up only after the plant fell it is possible that there was some root damage and this is causing the lack of water.  It is good that you are using non fluoridated/chlorinated water since this means we can eliminate this as a potential cause of the problem.  I would trim the tips and continue to only water the plants when you feel the soil has become moderately dry.

Q. Dear Peter, We live in Graham and love to raise our own potatoes because they are fun to raise and taste better than the ones from the store.  However, we got a lot of potatoes last year that are hollow and dark or rotted in the middle.  We planted Kenebecks’s last year and the year before we planted Yukon Gold and had the same problem with them.  The smaller to medium potatoes don’t have as much of a problem; however we can count on the huge to larger ones to have the problem in each one.  Is it something with the watering, or perhaps the soil? We have a nice sandy soil, which was a 5-way garden mix we ordered for the raised garden bed.  We have a water softener and the garden gets watered with the softened water because we don’t make a habit of going in and changing over the softener to regular water when watering the garden.  We would like to plant potatoes again this spring, but it is disheartening to lose so many to this problem.  We also like to share our garden with friends and family and it is embarrassing to give them something that is bad when you can’t see it.  Sincerely, Yvonne Fullerton - Graham, WA

A. Oh yeah, there are so many tasty potato varieties available and their numbers completely dwarf the varieties available commercially in the grocery stores.  The condition you are describing is called Brown Center and/or Hollow Heart.  These are two descriptions of a physiological disorder caused by the same conditions.  Hollow Heart is a more advanced expression of the disorder.  So there is no pathogen or insect involved.  It seems that when potatoes are grown in a cool moist soil some cells can die off in the center of the forming potato (I think they call this moisture stress).  Then if this period is followed by a warm period and quick growth this brown center can separate causing a hollow center.  That sounds just like our weather - cool and moist in the spring and then nice and warm once the sun comes back out.  It shows up more on larger potatoes because their relative growth is more rapid than smaller varieties.  Even if some cells die in the center of a small potato they don’t usually separate and can actually move and disperse as the potato grows.  Now you know that some of the varieties you are using are susceptible to this condition.  Try other large varieties especially if they are listed as resistant to Brown Center / Hollow Heart. Another recommendations often made is to use larger potato “seeds” (the starter tubers are called seeds). This strategy probably gets the tubers past their vulnerable stage. As far as your using softened water you should be aware that softening replaces magnesium and calcium ions (both plant nutrients used by plants) with sodium (which is not a plant nutrient).  Salt can build up in the soil and can interfere with plant growth if levels build up (remember the Romans and Carthage?).  But since you have sandy soil the buildup may be negligible, but it is good to be aware of this.  Try not to be too embarrassed about your less than perfect potato gifts.  They are still edible.  Did any of your friends and relatives grow their own gifts?

Q. When I am out in the yard, I can hear the traffic from Highway 16, foghorns, sirens, and trains.  The highway noises bother me the most because they do not seem to be constant or short-lived, the trucks and motorcycles seem to be the worst offenders.  Is there anything that I can plant to deaden the sound and turn the yard into a peaceful, quiet retreat?  The highway must be at least six blocks away.    Thanks,  Karen Osterman - Tacoma, WA

A. Well if you can’t see the highway from your home then I am afraid a hedge of dense evergreens like arborvitae won’t do the trick.  The major benefit of these kinds of screens is more psychological.  I say this because studies have shown that shrubs and other landscape modifications reduce traffic noise only by a few decibels and usually only the higher frequencies. (e.g. Traffic Noise Attenuation as a Function of Ground and Vegetation by Rudoff Hendricks, 1995).   Sometimes when vegetation is removed near highways there are more complaints about noise.  This is because the noise source is visible and the traffic sound changes in quality (the higher frequencies make the sounds more noticeable).  Sometimes white noise that can be produced by a landscape feature like a water fountain can help mask traffic sounds (psychoacoustic) so that could be an option, but you still may notice loud bursts of sound.

Q. How do I know whether my apple trees (and the apples) are damaged by apple maggot or codling moth? Nancy Pearson - Lakewood, WA

A. The easiest way is to look at the damage.  You’ll need to cut the apple in half (yuk) and then look at the feeding pattern.  Apple maggot larvae are about half the size of the codling moth larvae.  That is relative to the size of the adults since apple maggots are quarter inch flies and the codling moth larvae is about half an inch.  Apple maggot flies lay their eggs randomly on the fruit.  They stick their ovipositor just below the skin of the fruit to lay their eggs.  The eggs hatch out and feed randomly in the fleshy regions of the fruit making tunnels.  Codling Moths lay their eggs somewhere on or near the fruit and the larvae hatch and usually enter the fruit at the base and eat along the core (feeding on the core and the developing seeds).   Once you know the culprit you can start a monitoring and control system.  There are traps available for the adults of both species.  The apple maggot traps use the enticement of “food” to trap adults, which I have mentioned in past articles.  The Codling moth traps use the promise of sex in the form of a synthetic pheromone that traps male moths.  Trapping isn’t 100% effective control so you will need to use these to both control the population and monitor other control methods.  Both species return to the soil to pupate to adults so this is a vulnerable stage as well.  Keeping infected apples from falling and laying on the ground will help control both, but a sticky band around the trunk of the tree is advisable because in addition to hitching a ride with a fallen fruit the codling moth larvae may sometimes exit and crawl down the trunk of the tree to the soil.  Beneficial nematodes can be used to control larvae of both species that are in the soil and I think there is some promise in neem soil drenches that are now being registered for various soil grubs and larvae.

Q. I had mildew on my peonies for the first time this year. The phlox have it every year but never the peonies. What would cause it? Thanks Marilyn Dowson - Canada

A. I bet you are wondering if the disease spread from your phlox to your peonies.  It is doubtful.  The mildew you are referring to is powdery mildew to which most phlox are highly susceptible.  Powdery Mildew is a common name used to refer to many different pathogenic fungi that attack ornamental and crop plants and appear as a white cast on the surface of leaves.  In the case of phlox the species is Erysiphe cichoracearum .  As a general rule different species of Powdery Mildew have very specific hosts and a few have a larger host range. Although Erysiphe cichoracearum has a relatively large host range the hosts are considered limited to plants in the Aster Family (Asteraceae/Compositae) (e.g. chrysanthemum, dahlias, phlox, sunflowers and zinnia).  A probable scenario is that your peonies have another fungal disease called botrytis (Botrytis cinerea) or grey mold.  If you find infection of the flowers then this is a good indication of a botrytis infection.  Both fungal diseases are exacerbated by lack of air circulation and humid conditions.  The fungal spores need some moisture present on the surface of the plant to germinate and grow.  It could be from overhead watering or even from dew that forms overnight and doesn’t evaporate due to poor air circulation.  So anything you can due to change the environmental conditions will help.  Sanitation (removal) of infected leaves is also helpful since you reduce the spores available next season.   Both diseases can be controlled with copper based fungicides.

Q. Dear Peter, I like to mulch my rose bushes during those months that we have lower freezing temperatures, which our area is more prone to have.  Is there any difference between using fir/pine needles and using deciduous leaves (usually ground up by my mower) to mulch tender plants? Betty Jones - Graham, WA

A. Most of the modern roses and grafted roses will appreciate some winter protection from our worst winter weather.  They may make it through some mild winters but during our “zone defining” winters there can be some dieback on some varieties of roses.  I have rugosa hybrids and an eglantine rose (old rose) that don’t require any winter protection.  Our local rose society is a good knowledge base for what varieties grow well or need protection in our region (http://www.tacomarosesociety.org/). Consider attending one of their regular meetings.  There are many materials that are recommended for protecting roses.  These materials are usually mounded around the base to about a foot high to protect the graft union and the lower buds of the rose.  The simplest and probably oldest method is to bring soil from another part of the garden and mound it around the base of the plants.  I say from another section of the garden because you don’t want to pull up soil from around the plant itself since you will expose the feeder roots to winter damage.  Wood chip mulch, manure, compost, sand, hay as well as leaves and needles have all been recommended at one time or another.  The lighter of these measures will require chicken wire ring to keep them from blowing away.  As far as I know there are no studies as to the thermal resistance value of these various methods but there are a few things to consider in your choice between leaves and needles.  To prevent disease problems during the winter you need to keep excessive moisture away from the canes.  Because of the amount of rain we get the chopped leaves have a better chance of matting down and becoming water logged. This means using well draining mulch.   Therefore given the choice the needles may be superior.  You can also get the benefits of both by mixing them up so that the needles keep the leaves from matting down and getting water logged.

Q. This year my Early Girl tomato plant had an abundance of blossoms all summer but did not produce one mature ripe tomato.  Another tomato plant in the same area did fine. Walter Lachnit - Gig Harbor, WA

A. Tomato blossoms are self contained with male and female parts so usually the wind or insects will pollinate them.  I sometimes getly tap the flowers or the cage to jostle the flowers which will help pollinate them.  If it is not a question of pollingation then there are two main factors that determine the success of a tomato to produce fruit - nature (its own genetics) and nurture (the environment that the plant finds itself in).  The major environmental factors that will influence the tomato are water, fertilizer, sun, heat units and culture.  Irregular irrigation usually shows up as blossom end rot in many tomatoes because calcium isn’t absorbed as well in dry soils and calcium is necessary to make plant cell walls.  Make sure the soil stays evenly moist.  Fertility of the soil can be a double-edged sword.  Too much fertility can result in excessive foliage growth at the expense of fruiting.  Sun duration should be at least 8 hours a day, and more is better.  Heat units are at a premium in our cool growing season so we look to genetics of our tomatoes since there is only so much we can do beyond growing them on a south facing wall (the other option is to grow tomatoes in a greenhouse).  Usually in our area we look for cool season varieties that have the genetic capacity to produce with fewer heat units.  Another genetic factor is the growth habit of the tomato.  There are determinate and indeterminate types (actually there are some intermediary hybrids but let’s keep it simple for now). Determinate tomatoes are bushy and tend to produce their fruit in a more condensed period.  This is because the flower buds terminate growing points. These are usually grown in cages. Indeterminate tomatoes tend to be taller and more vining in nature because the flower buds do not terminate the growing points and the plant just keeps vining along sending out flowers from the sides. The fruiting period is spread out and not as condensed. These plants are usually pruned to a stake and trained to one or two stems.  The ideal in our region is to get a short season determinate tomato.  Early Girl is a short season indeterminate but is still considered a reliable producer in our region.  An example of a short season determinate variety is Oregon Spring.  When I grow indeterminate tomatoes I always pinch out top growth and any lateral branches before they make a run for the top. On all my tomatoes I start pinching out all new flower blossoms after the end of August.  This makes sure the plants energy goes into the existing fruit to develop and ripen them. I am curious if the other plant you mention that did fine was also an Early Girl. If the environment of both plants is identical then we may have to chalk it up to genetic variation within this cultivar of tomatoes.  Every plant is an individual even in a fairly uniform hybrid like Early Girl.  Or perhaps a rogue seed of another variety made it’s way into your seed pack or if you bought it as a plant it was mislabeled.  Hopefully understanding the factors will help you to determine what may have happened and help you in your future tomato growing endeavors.