I thought about this nature note while working in the perennial gardens at the arboretum. You get a good dose of what’s a “good” plant and what’s a “bad” plant while weeding in unfamiliar beds. Even I have to look carefully to determine which new sprouts are “OK”, and I developed most of the beds and chose the plants for them!

One of the “bad” plants is a spring-flowering, bulb-based, perennial lily commonly known as “Star-of-Bethlehem” (Ornithogalum umbellatum). It is a “sneaky” plant because its leaves look surprisingly like crocus leaves. The plant gets to be 10-30 cm high and has linear, channeled, green leaves each with a white line on the upper surface. It develops several star-shaped, white flowers, which are 1.5-2 cm broad. Each of the six white petals of the flower is backed with a green midstripe. Sounds pretty nice, right? Well, unlike crocus, it quickly becomes invasive and is a pest in lawns. Leave one now, and you will have 50 more next year. Much of the early spring weeding in the arboretum is spent digging up the bulbs of these invaders.

All parts of this plant may cause discomfort if ingested, the bulb is poisonous, and the sap may irritate the skin. A good habit is to wear your gloves while gardening to prevent irritations from plant sap, in general, and also to keep your skin from drying out.
By the way, after this Friday’s work day in the arboretum (3-5 pm), I will hang around to point out some of the “good” species we have there and if anyone wants to, we can then go down to the Western Walking trail and see what’s blooming.

Now, I know spring is here! Not only are all those early mustards (discussed in nature notes in years past) in bloom and fruit, but male goldfinches are turning bright yellow.

You can identify birds by their vocalizations, but you can also make use of the striking colors of some birds to distinguish one species from another. The American goldfinch is a fine example: the males turn bright yellow as spring develops. The yellow is accented by black wings, tail, and forehead patch. In the winter, however, both sexes are basically a grayish, dull, yellow-olive color with dull black wings.

Birds show many different variations in the color and pattern of their plumage. Very simply, plumage color is either produced by pigments or by special structural particles embedded within the feathers.

As you know, different pigments absorb different wavelengths of light energy and reflect others. We see reflected wavelengths of light as color. Thus, male cardinals appear red because red wavelengths of light are not absorbed by the pigments of their feathers, but are reflected back to be perceived by our retinas.

Some birds also display blue and iridescent colors and these are considered “structural” colors. The blues are produced by particles while the iridescent colors are caused by differential reflection of wavelengths from modified barbules of the feathers. The structure and angle of these barbules affects the reflecting surface the light hits and this, in turn, affects what we see.

The pigments that develop are determined to a certain extent by diet. Certain dietary amino acids, vitamins, etc. affect the production of various pigments. Thus the plumage colors can be changed depending upon what the bird is eating. In the spring, the colors of the male goldfinch changes as diet changes, in combination with changing hormone levels.

Plumage coloration is useful for several purposes, among them, species recognition, courtship, threat displays, and camouflage for concealment from prey and predators.

Something to think about in the field of evolutionary biology: If you were a female goldfinch, which male would you choose to mate with: one with dull yellow plumage or bright yellow plumage? You would probably choose the highly colored male since the color indicates a well nourished bird. A well nourished male would be a good “provider”. It would follow that offspring survival would also be affected favorably.

In case you haven’t noticed, spring really is on its way. Longer day length, returning birds, increased bird calls and birds songs are sure signs.

So what’s the difference between a bird CALL and bird SONG? There is a rather arbitrary distinction made between these two based on the length and complexity of the vocalization. A CALL is considered shorter and simpler and such vocalizations are produced by both sexes throughout the year. A SONG is longer, more complicated, and is produced by some male birds during the breeding season. With a few exceptions, female birds do not sing.

Calls have specific functions and are given in particular situations. Calls are considered innate rather than learned. Examples of calls include alarm sounds, locations calls, and notes given during fighting. Some calls can actually communicate across species.

Song is considered learned to a certain extent. Song serves to identify one species from another, as well as advertise territory and attract mates. The males of many species of songbirds, also known as OSCINE PASSERINE species, (perching birds in which singing is highly developed) actually have two or more songs, each with different syllables and phrases and involving different repetitions. Ehrlich et al. (1988) report that the brown thrasher is estimated to sing in excess of 3,000 song-types! Quite a “song repertoire”!

By the way, because birds produce vocalizations via a structure called a SYRINX located in the trachea. Many birds can sing with their mouths full or even closed!

A few people have asked me my thoughts about the recent damage to trees from the ice storm. A few comments follow.

Remember that, in a forest, trees get pruned naturally. Competition for light, physical contact between closely packed trees, and the physical forces of nature (weight of snow, ice storms, wind against diseased limbs) will cause lower branches to drop resulting in a tall, straight trunk which is desirable. Trees weakened by disease within the trunk are also eliminated due to such environmental stresses of nature. (Take a look inside the exposed trunks of older trees which snapped as a result of our recent storm—you will see several with “heart rot”: the inner portions are soft and rotted.) The worst ice storm damage involves trees where the main trunk leader snapped off. The tree will survive, but side branches will begin to fill in and a main leader may not develop. This can lead to an unattractive form and a less than strong structure. There is really not much you can do about this. You can try to prune it, but may want to remove the tree instead.

If you have a lot of damage, get an arborist in to assess your trees and shrubs. You might as well let that individual handle the pruning and perhaps even prune/thin some of your undamaged trees at the same time. Beware of non-professionals driving along in their pick-ups in your subdivision asking everyone they see if they want their trees cleaned up.

If you want to “do your own thing”, read previous nature notes (last year and this year) on pruning to help guide you. They are archived on the biology web site. In the case where side branches have snapped, saw them off as close to the trunk or connecting larger limb as possible. In the case where a main trunk has snapped and you think you can handle it safely yourself, you will have to use your best judgment. The tree will heal, but the form you are left with is what you need to look after.

Read the information in the article by Heather Harris on the front page of the Georgetown News-Graphic (March 2, 2003). The advice given by our county extension agent, Mark Reese, is excellent. The accompanying “tips” section is also good.

I hope you took a stroll around the yard and did some pruning last weekend during the warm weather. If, at that time, you noted that some of the bark on your trees was damaged in some way, don’t panic. The best thing you can do is cut off any ragged ends or loose bark and leave the tree alone to heal itself.

This weekend, inventory your shrubs. Examine them first for disease and insects. One problem you might encounter, especially on euonymus and cotoneaster, is scale.

Armored scales are insects which are small, flattened, and disc-like. They live under a shell made from wax secretions and cast skins of earlier growth stages. (Remember, insects advance through several developmental stages or, molts, on the way to becoming adults. Molting involves shedding of the insect’s hard, outer exoskeleton. Stages between molts are referred to as instars, and each instar varies in appearance and size.). Scale insects settle onto stems to suck sap. If you can a scrap armored ovals off your branches with a fingernail, you know you have scale.

Most armored scales feed on trees and shrubs, but you can also find them encrusting the stems and leaves of houseplants.

Dealing with these pests on your shrubs is handled in a couple of ways. You can prune your shrubs back a bit in order to remove the most infected parts. To prevent further spread, burn these stems or soak them in a Clorox solution. Then, spray the shrub with an application of “dormant oil”. This can be done as early as March if it is above 40º F outside. Dormant oil smothers the scale insects. The warmth of spring will motivate the critters to crawl around which means they will spread. This is when you hit them with “horticultural oil”. Be sure to spray under the leaves and branches as well as from the top and sides. You can use the horticultural oil as a dormant oil as well. Check your local nursery or Wal-Mart for these sprays and follow the directions.

I am still on sabbatical, but back on campus until May and have heard from enough of you to know that more nature notes are needed! So, I will once again send out weekly tidbits of information to keep you inspired about the living world around you. In addition, as we get into March and April, Bill and I will be taking some local field trips to observe wildflowers and hope that some of you will join us.

I am sure you are beginning to look around for outdoor things to do to “get the jump” on spring and as an escape from those odious indoor tasks we do in the winter. Well, this is a great time of year to do some tree pruning because leaves are not covering up the problems. Take a slow walk around your property and carefully observe each tree in your yard from several angles.

1. Are there branches crossing over other branches, thus impeding the proper growth of your tree? If so, eliminate the culprits.
2. Are your trees beginning to look like shrubs because you have not pruned them high enough? If so, clean up the trunk. You want a strong, well-defined “bole” trunk) and now is a good time to clear out those lower limbs before they get too big. (A good rule of thumb is to prune a tree trunk at least as high as you can reach.)
3. Prune to thin dense growth. (Thinning involves removal of an entire branch back to a main branch or trunk.) Thinning will allow more light and air into the interior of the crown and reduce danger of breakage caused by ice and snow loads. This is particularly important in the case of Bradford pear. You might need to hire an arborist to clear out some of the interior branches of your Bradford if it is particularly large. Bradfords develop a very dense crown and when confronted by intense gusts of wind, their brittle wood gives way and the trunk breaks. You can increase the longevity of these less than stable trees with a good interior pruning.
4. Prune out limbs broken by storms.

Some of you may remember when tree paint was used to “protect” a cut limb, but research shows this is no longer necessary. Do protect trees you prune by disinfecting your hand pruners or pruning saw between trees so you don’t spread disease from one tree to another. This can easily be done by wiping down the blades with alcohol as you finish one tree and move to another. By the way, you should use a saw for cutting a branch or stem thicker than one inch in diameter. You need to make a clean cut, and if you use a tool smaller than needed for the task at hand, you will produce a ragged edge and invite disease. Obviously, sharp tools are best.

I know, it is cold out, but being out surveying the trees might be better than cleaning your oven this weekend!

It is once again time to spray for boring insects that attack flowering dogwood and lilacs. Spraying the trunks in May and June and maybe once more in July will help prevent this problem. It is pretty hard to keep boring insects out of dogwood, but spraying with lindane can help. As always, read the directions on your insecticide.

If you have not started to trim the new growth on your shrubs, you need to get busy. The new growth is beginning to form wood now, and once this occurs, you often have to hand prune rather than use an electric pruners. In addition, if you don’t actually cut back into the wood every couple of years, your shrubs will tend to get larger even with general pruning of the new growth. If you need to keep shrubs clear of windows and walkways, you will need to create a cutting back and pruning plan. Explaining that to you is too difficult via this venue, but there are books to read, and, as always, I would be happy to help anyone who asks.

If you have pines, new growth appears as “candles”. These, too, need to be cut back in order maintain a reasonable size and shape to shorter pines such as mugho pine. You can just trim off the new “candles” before they open up, or, cut into the wood further back here and there. This will not only remove the new growth, but will open up the inside of the shrub so light can stimulate new leaves to develop in the interior of the plant. Of course, this same idea is true for angiosperm shrubs. I cut into the interior of my shrubs periodically throughout the growing season to open them up: not enough to leave gapping holes, but enough to let some light into an otherwise leafless interior. Taller gymnosperms such as junipers also need to have the new growth pruned before it “hardens”. Once again, you need to do this to maintain desired shape and size of the plant.

It is possible to keep your shrubs contained and looking nice without hacking them down. You just have to plan and take your time. The time factor increases as the shrubs increase in size. Most people don’t like this aspect of gardening, but when well done, your home will appear much neater and cleaner, and have a much greater “appearance value”.

If you are looking for trees to plant in your yard, there are many things to consider. First, and most importantly, you want to be sure the species you choose will do well in the environment in which you want to plant it. The species you choose must be adapted to the type of soil, drainage, and shade conditions you provide for it if it is to survive. (Check out books on trees and shrubs which will provide you with this information.) Secondly, be sure the eventual size and spread of the tree will suit you several years down the road. Third, don’t plant too close to your home, consider the eventual size and spread of the tree and plan for it. A small tree will look just as good planted several yards away from your house as right next to it, and you will not have to cut it back (or down) in 5-10 years because it is blocking your view, hitting your house, or filling your gutters with leaves and seeds.

You can purchase very small trees as “bare root” stock, or larger ones that are in containers or balled in burlap. No matter what size you choose, treat these new friends with kindness and plant them correctly. There are many books that can help you with the do’s and don’ts of planting. The biggest problems occur when you plant the tree deeper than it has already been planted (if containerized or balled in burlap), not tamping in the soil around the roots so air pockets form and the feeder roots dry out and die, and filling in the planting hole with a soil mix that is not like that where the tree is planted. In other words, don’t fill the hole in with a “perfect” soil mix or peat moss because the roots will never grow out of the immediate space, and you will end up with a “pot bound” tree growing in your yard. Finally, never heap mulch around the trunk of the tree. Mulch holds moisture and will rot the trunk if it is left heaped next to it. (Yes, it is not done correctly on campus in most places! Professional landscapers love to heap mulch-and you pay for it.)

Finally, to stake or not stake your new tree. Many people think staking a newly planted sapling is important. New research indicates that you should not stake a tree. Apparently, natural stress increases the tendency of the tree to build up the proper amounts of lignin to support itself. (Lignin is a phenolic compound that serves to reinforce the walls of the cells of the supporting tissues in the trunk and branches of woody plants. It adds compressive strength and stiffness to the cell walls in which it is deposited.) If the tree is planted properly to begin with, it will not lean.

Now, go forth and plant!

One windy day as I was watching some “black birds” balancing on some less than stout branches in a tree in my yard, I thought of the faculty and staff on campus “balancing” all the work we have to complete at this busy time of the year. I noticed that when the wind became too strong, the birds moved into the interior of the tree where there was more protection and thus it was easier for them to “hang on”. Again I thought of my Georgetown colleagues and decided we should learn a lesson from this observation. My advice: allow yourself to move into the “sheltered branches” once in a while, to give yourself a rest. None of us should feel we have to “hang on” continually as the stress of life presses down upon us similar to the wind tossing the thin tree branches I observed.

The eastern tent caterpillars, Malacosoma americanum are on their way out! The larvae of this species will congregate to construct a protective silken tent, usually in the fork of a tree branch. They particularly like to build tents in black cherry, apple, and crabapple trees, all of which are in the rose family. If you find tents in your trees, you need to spray (check out pesticides such as Malathion) to eliminate the multitudes of caterpillars that are maturing and will begin to consume the foliage as they emerge. After defoliating trees (and dropping on your head), these caterpillars will spin a cocoon and eventually develop into “small to medium-sized”, heavy-bodied, rather hairy, brownish moths about three weeks later.

Yes, there are birds which enjoy tent caterpillars at mealtime. Especially fond of these creatures are the cuckoos. In fact, Bird Watcher’s Digest (2002, vol. 24(5): 40) says cuckoo breeding abundance depends on the availability of caterpillars, especially tent caterpillars. In our area, we have the yellow-billed cuckoo; the black-billed breeds in eastern Kentucky.