Gardening Tips from Illinois Gardener on WILL-TV
Thursdays at 7 pm - repeated Saturdays at 11 am
One of WILL-TV's most popular programs, Illinois Gardener features experts with extensive knowledge of horticulture, landscape design, and entomology. Dianne Noland and her panel of experts answer viewer questions about gardening. Call in your questions during the show at 217-333-3495.
Common Backyard Pests
Are you having problem with any insects in your garden? Jim Appleby, our resident entomologist, offers tips and information about common pests found in backyards
Mealybugs
This insect pest can infest nearly any plant that can be grown indoors. The first indication that an infestation is present is the white cottony masses that might be seen on the undersides of the leaves, in leaf or branch axils, and in any concealed areas on the stems. It is in these white cottony or waxy masses where the female mealybug produces their eggs. The female mealybug may produce as many as 300 to 400 light yellow to orange eggs in the cottony masses.
After about a week, the eggs will hatch into tiny pale yellow-orange nymphs or crawlers. The nymphs will move about the plant searching for feeding sites. The undersides of the leaves, especially along the main vein, and in the leaf axils appear to be the most desirable sites. Once the site is selected the nymph will insert its piercing-sucking mouthparts into the plant tissue and begin feeding. The nymph may feed at the site for about three (3) weeks or if after awhile the site becomes unsuitable, it will withdraw its mouthparts and crawl to a new area.
Nymphs
When hundreds of nymphs are feeding at the same time the plant will become weakened. The plant's foliage may turn pale, and the new growth may be greatly stunted. If the soil becomes dry the plant will wilt much sooner than normal.
After completing their nymphal stages which lasts about three weeks, the mealybugs will become adults. If the are males, they will emerge from very small white cottony-like cocoons as small winged insects. The males will fly to the females and mate with them and then die. The adult wingless females continue to increase in size and begin to produce large amounts of waxy, cotton-like substance around their bodies. Within the cottony masses are produced the numerous eggs. When all the eggs are produced the female dies. All stages of the mealybugs may be present on a plant at any time. If uncontrolled the mealybugs will eventually kill the plant.
Honeydew
During the nymphs' feeding they will excrete sugary clear fluid called honeydew. The honeydew will fall onto leaves and other objects beneath their feeding sites. The leaves at first will become very shiny and feel very sticky. Then a black sooty fungus will start to grow on the honeydew. The leaves now appear to have a black or grayish-black film. Because of the amount of light available to the leaves is greatly reduced due to the sooty fungus, the affected leaves are not able to function normally and will die.
Control methods
For control, first try to remove as many of the large female mealybugs as possible. This can be accomplished with a cotton swab that is used to crush the insects. Then thoroughly spray the entire plant with an insecticidal soap. The soap treatment must be repeated at weekly intervals until a total of four (4) treatments have been made. The repeated applications are absolutely necessary because the soap treatment will not kill any undetected adult female mealybugs or any of the eggs. Soap will only kill the younger nymphs, but eventually with repeated spraying, all of the nymphs will be killed. Be sure to follow all instructions on the soap label.
European Pine Swanfly
During the months of April and May, red, mugo, Scotch, and Austrian pines are often attacked by the larvae of the European pine sawfly. The larvae are very gregarious, and will almost always feed in groups. The larvae feed only on the old needles; the new needles produced during the spring months are never fed upon.
The mature larvae are about an inch in length with shiny black heads, the rest of the body is gray-green with black longitudinal stripes. With the least disturbance, the larvae often will twitch in unison. This behavior is probably a defensive maneuver to ward off predators and parasites. All the larvae twitching together may appear as one large animal rather than individual larvae.
If the larvae are abundant in many areas of a true, their feeding may cause complete defoliation of the of needles. Such defoliation will not kill the tree, however the tree is weakened. The following year the new growth may be stunted. Trees devoid of their old needles have a poor appearance.
Control Methods
If a sawfly infestation is very light with only a few trees affected and only a few branches infested, then a cultural control can be used. Pour some hot soapy water into a pail. Hold the pail beneath the infested branch and flick the larvae into the solution. When an infestation is heavy, an insecticide spray may need to be applied. Acephate (Orthene), malathion, or carbaryl (Sevin) applied as a spray will control the larvae. There is no need to spray the entire tree, apply the spray only onto the larvae. Bacillus thuringiensis will not control sawfly larvae. Sawflies are related to ants and wasps and B. thuringiensis is effective only in controlling moth and butterfly larvae.
IPM of Midwest Landscapes
How to order the book IPM of Midwest Landscapes ($54.00)
Send a check payable to the University of Illinois to:Dr. Susan Ratcliffe
Dept of Crop Sciences
1102 S. Goodwin Ave.
Urbana, IL 61801
or visit the North Central IPM Center website, or call Dr. Ratcliffe at (217) 333-9656.
Pruning Basics
Winter is a perfect time of the year to prune shade trees.You can see the overall structure of the plant during winter. Before pruning, you should know about tools, and the principles of plant growth.
Tools
There are four basic tools which can be used in pruning:
Scissor-action hand pruner
The two blades of this hand pruner cross each other and make a clean cut on the bark and cambium layer.
Anvil type pruner
This pruner is not recommended because it causes too much damage to the branch. Both types of pruners mentioned above are for use on branches no larger than 1 3/4 inches in diameter.
Big lopper type pruner
This is used for branches that are that are 1 1/2 inches in diameter or smaller.
Hand saw
The hand saw works on a pulling action. It is used for branches greater than 1 1/2 inches in diameter. If you need to use a hand saw to prune, you have probably waited too long to do the pruning.
Tree Growth
Understanding the plant growth of trees is very important. Meristem growth in shade trees always forces growth up to a new meristem. It branches the next year and sets new meristems. These branch the following year, and again set new meristems. The tree growth is always up and out from the original source. The lower branches don't move. The only way to trim old growth is to actually remove the branch.
The tips of branches produce buds, which in turn create hormones that keep buds lower down on the branch from breaking or opening and forming new branches. This is called apical dominance. If you cut those buds off, you stimulate more growth lower. If you leave the outer buds, you inhibit growth down below.
The third factor is bud growth. A typical branch will have two buds on it. Depending upon which breaks will determine the direction of the new branch growth.
Pruning
There are two types of pruning cuts: a heading back cut and a thinning out cut. With a heading back cut, you leave part of the branch, forcing new growth along it. A thinning out cut removes the entire branch back to the trunk of the tree.
When starting to prune a shade tree, only take one third of the plant off at a time. A simple reference is to take a photo of the tree before you begin. The priorities of pruning are:
- First, remove any diseased or dead wood.
- Second, remove any branch that may compete with the central leader.
- Third, remove branches with very narrow crouch branches. Shade tree carry a lot of weight and narrow crouch branches will eventually split out under the weight.
- Fourth, prune cross branches. A cross branch is one which crosses the main trunk of the tree. A cross branch can cause damage or disease to the main trunk or branch by constant rubbing.
Whenever you use a thinning out cut, be sure not to cut into the collar of the branch. This is the area where the branch meets the tree.
