Extension Educator, Local Food Systems and Small Farms
Extension Educator, Horticulture
October 31, 2008
The cooler nights sure make for better sleeping weather, but they are also a sure sign that fall is on the way. With the cool weather, we have quite a few insects that are looking for a warm place to be. Insects look to "sun" themselves on a south or west facing wall to catch warmth in the afternoon. That brings us to nuisance pests.
A nuisance pest is anything that causes us grief. Ones that I would target as nuisance pests right now include: Asian lady beetles, ants, crickets, boxelder bugs, elm leaf beetles, and woolybear caterpillars. All these things are in and around the house, and generally making things miserable for us.
With nuisance pests, the best offense becomes a good defense. We can start with a barrier pesticide application on the foundation of the house (and the adjacent foot or two of soil around it) with something like permethrin insecticide. This puts down a barrier that insects crawl through when trying to get in or on your house. Insects may not die immediately, but shouldn't last long after crawling through this barrier. In severe cases of insects congregating on outside walls, entire walls can be treated. Just make sure you test apply the chemical to a small section to make sure you don't discolor siding.
Of course, if insects are already in the house the barrier won't stop them. Inside the home, only aerosol products should be used. The safest of the group are the ones for flying insects that contain pyrthrins or their derivatives. These products basically kill insects that you get the spray on, and the sprays are inactivated by hitting the wall, floor, or other surfaces. You can spray the air in a particular room and vacuum up the dead insects in an hour or so. This is one way to get insects inside the house. Remember the toxic principles of pyrethrins and pyrethroids on dogs and cats, particularly with direct sprays.
Another useful tactic, particularly with ants and crickets, is to use baseboard type sprays. These products are typically labeled ant and roach type products, and may last for several weeks. Just spray in the high insect traffic areas, along baseboards, to put down a lasting barrier inside the house.
For ants, the bait stations also offer us the opportunity to kill the entire nests. The bait stations are probably the most effective, but should be used alone for at least a week. Then you can also use the baseboard type sprays. The idea is to let live ants get to the bait and take some to the nest.For those that don't like to use chemical products, the use of sticky boards (like the type used for rats and mice) offer an option. Place these in areas where many insects are seen, such as room corners and under stairs in the basement. The vacuum cleaner is also a good option for cleaning insects from draperies and the like.
October 28, 2008
We not only had a frost, but a hard freeze to boot this morning. My thermometer read 23 degrees this morning at about 6 am. There are some garden issues to address quickly due to the cold.
First off, I'm sure it got cold enough that no rhubarb should be used. The freezing, usually temperatures below about 27 degrees or so, will damage the cells in the leaves releasing a toxin into the stems. This makes the rhubarb toxic.
Other crops, especially vining crops, should have the stems cut quickly. This will prevent stems from rotting back into the vegetable. Pumpkins, squash, and cukes are all in this group. Sweet potatoes are especially sensitive, and after the freeze you have about a day to get the tops cut to keep the tubers from spoiling. The general rule for most garden items is to go ahead and cut off the top portions of plants for underground parts you want to keep. This doesn't mean you have to dig your turnips immediately, just cut the tops off.
Crops such as turnips and carrots can then be left in the ground until needed, or the weather really gets cold. Mulching with straw or grass clippings will add some insulation to the soil level in the area. This insulation will keep the temperatures more moderate. Many people consider this type of storage will actually "sweeten" the vegetables after a frost.
October 27, 2008
With a little bit of wind, or a lot of wind this past weekend, the leaves have begun dropping in large numbers. This brings up one of those age old questions "What do I do with all those leaves?" The simple answer is to give you three options: leave them (no pun intended), remove them, or chop them up.
If you decide to let nature take its course, letting leaves lie brings benefits and some problems. Many of the benefits are associated with your labor, or lack of it. The major non-labor benefit is when leaves collect in flower beds and around shrubs to provide a mulch for those plants. Problems generally develop where deep piles of leaves may smother grass or harbor diseases, causing large dead areas to deal with next spring. Of course if you are the only resident in a neighborhood who doesn't rake leaves, you may be talked about at many social functions this fall.
Removing leaves is generally done by raking or bagging with a mower attachment. This makes your lawn look neat, prevents problems for lawns, and gives you a workout if you are manually raking. The main problems are the time, labor, and disposal of the leaves when they are piled.
Chopping leaves means reducing the size. Benefits include less smothering, quicker breakdown, and less labor. The main drawback comes with deep piles that still should be removed because of trouble in shredding and smothering.
One thing to consider is the type of leaves. There is a huge difference in oak leaves and silver maple leaves. It's difficult to have smothering problems with oak leaves, while silver maple leaves may smother with a very thin layer. Many green leaves were blown down Sunday with the high winds. These green leaves will tend to smother more than the dry, rigid types will.
What do you do with the leaves you've accumulated? There are several possibilities. Many municipalities, Lincoln included, prohibit burning for the most part. Besides the fire risk, the respiratory issues for affected people can be life threatening. Raking leaves into the street, unless requested by the city for cleanup, usually results in clogging storm sewers. Options remaining include composting, using as a mulch, tilling into garden and bed areas, and hauling to the city landscape recycling dump. There may even be some private collection services that will take bagged leaves to a recycling center. Partial composting, and the subsequent use as a mulch, is one of the best solutions. Simply construct an enclosure at least two feet cubed, place leaves in it, and cover the top with hardware cloth or wire laid on it and weighted down. The resulting much may be used next spring on flower beds, gardens, around trees and shrubs, or spread back on gardens or lawns.
One thing to consider is removing the leaves from around the foundation of the house. The decaying leaves provide a hiding place or food sources for nuisance pests such as lady bugs and millipedes. The removal from directly around the house may reduce the number of these insects making their way into your home.
October 21, 2008
Many of the roses that are classified as old garden roses are extremely tolerant of cold temperatures, while others like hybrid teas experience considerable damage. Also, budded roses stand a greater chance of injury or death due to severe cold than do own-root roses. When selecting roses, always select cultivars that are able to tolerate the coldest temperatures in your area based on USDA hardiness zone maps. One of the ways to protect roses for the winter is to be sure they go completely dormant. To accomplish this, stop fertilizing early enough so growth slows down. No fertilizer should be applied after August 15. To further encourage dormancy, stop dead-heading or cutting flowers after October 1 and allow the plant to form hips.
There are many methods to provide winter protection for roses. The whole idea of winter protection is to keep the plant uniformly cold and frozen all winter and prevent the damaging effects of alternate freezing and thawing. Whatever the method, don't begin covering plants too early. Wait until a hard killing frost has caused most of the leaves to fall, and the temperature has dropped into the teens for several nights. Prior to covering, remove any foliage or other debris that might harbor disease for the next season.
Before covering, some tall roses may need minor pruning to reduce their height, and tie canes together to prevent wind whipping. Pruning at this point should be kept to a minimum. Most pruning will be done in the spring to remove dead and diseased canes.
The most common way to provide winter protection is to pile or "hill-up" a loose, soil and compost mix around and over the plant about 10-12 inches deep. A variety of hilling materials can be used, but the key is to be sure that the material is well drained. Wet and cold is far more damaging than dry and cold. Soil that is used to "hill-up" plants should be brought in from outside the rose garden. After the soil mound has frozen, the mound can be covered with evergreen boughs, hardwood leaves, or straw to help insulate and keep the soil frozen.
A variation of the "hilling" method is one utilizing collars. An 18-inch-high circle of hardware cloth or chicken wire is placed around the plant. The collar is filled with soil, allowed to freeze, then mulched with straw. The benefit of the collar is that it holds the soil in place all winter and prevents it from being washed or eroded away.
Another popular method of winter protection for roses is the use of styrofoam rose cones. If these are used, they need to be used properly. First, don't cover the plants too early. Follow the general timing guidelines. Second, cones need to be well ventilated by cutting holes around the top and bottom of the cones. This helps prevent heat build-up on the inside during sunny winter days. It is also advisable to mound soil around the crown of the plant before putting the cone in place. For extremely tender varieties, some rose growers cut the top off the cone and stuff it full of straw for added protection. It is also a good idea to weight the cone down with a brick or stone to keep it from blowing away.
Climbing roses offer more challenges. For marginal varieties, climbers may need to be removed from their supports and bent to the ground, then covered with six inches of soil and mulched. When laying climbers on the ground for covering, one needs to be very careful not to injure or crack the stems. As the weather gets colder their long stems are more rigid, and they are easily broken.
Another method that can be used is to physically pack straw around the canes while they are still attached to the trellis or support. The straw is held in place with twine, chicken wire, or hardware cloth to keep it in place over the winter.
October 10, 2008
It's fall leaf time again, and those interested in the phenomenon of fall leaf color should be happy with the fall colors we achieve this year. We are entering the peak color period for this season. Frost is often credited with causing the great fall colors, but it actually kills leaves producing dull earth tone colors. Bright fall colors are caused by chemical reactions in leaves, and these reactions are triggered by shortening day length and cool temperatures.
To understand the process that creates color, we need to know a little about basic tree growth. A tree has two parts in its vascular system, the xylem and the phloem. A tree's xylem cells can be thought of as thousands of minute soda straws packed end to end, going from the roots to the leaves. Water and nutrients are taken up by the roots and transported to the leaves through the xylem cells in the tree's sapwood. In the leaves, water and nutrients are converted into sugar, the energy that feeds the tree's growth. This conversion process, known as photosynthesis, happens in the presence of chlorophyll and sunlight.
The phloem is a thin layer of cells found in the inner bark of the tree. This is where the sugars move from the leaves to the roots and other storage sites within the tree. The location of the phloem shows how a tree can be severely injured or killed if its bark is damaged. If the phloem is disrupted, food can't flow through the phloem and the roots starve to death.
Fall coloration starts with the onset of senescence, a natural process that disrupts the tree's vascular system. This is the orderly process in which the light gathering and carbon capturing substances in the leaves, including the pigments that capture sunlight and the proteins that use the captured energy are disrupted and broken down. The change is started by the tree's genetic ability to "sense" day length and temperature variations. Fall's shorter days with less light and different light intensity, along with the cooler and longer nights affect the production of growth regulators that trigger senescence.
The long and warm days of summer produce high levels of the auxins and gibberellins that stimulate tree growth and low levels of growth inhibitors. These stimulate a variety of changes, including the formation of corklike cells at the base of the leaf petiole, which produces a brittle zone around the vascular tissue so that it is easy for the leaf to break off from the branch. Eventually only the dead xylem cells are left holding the leaf on the tree. Heavy winds or rains can easily break this fragile connection, causing leaves to fall to the ground.
The shorter days and cooler temperatures get the tree ready for dormancy. Chlorophyll production drops dramatically from the high levels of the growing season to virtually nothing. The tree's priorities then switch to the production of sugars that will be stored for next season's growth. This reduction in chlorophyll production starts the visible fall colors. Chlorophyll is the predominant pigment and makes the leaves green during the growing season. Chlorophyll is also very fragile and must be replaced by plants on a continual basis until the days grow short and temperatures fall. The fading of the green color, due to much lower chlorophyll production, causes the other pigments once masked by the green chlorophyll to come through. These other pigments include yellow, orange, and buff colors of the carotenoid, xanthophyll, and tannin pigments.
Carotenoids are always present in the leaves, so fall's yellow to orange colors are usually fairly consistent from year to year. Xanthophyll is a yell to tan colored pigemtn and tannins are responsible for the brown earth tones found in oak leaves. A fourth pigment called anthocyanin does not naturally occur in the leaves, but is a product of senescence and concentrated sugar sap in the leaf cells. Anthocyanins appear red and generate the varying shades of blue, purple, and red that provide some of the most vibrant color displays. The actual color depends on the pH of the cell sap, with acidic saps causing red to orange and neutral to alkaline saps will appear purple to blue. Not all trees produce anthocyanins with sugar and red maples, dogwoods, sumac, blackgum, sweetgum, scarlet oak, sassafras, persimmon, hawthorn, and white oak producing the most brilliant shades of red, maroon, purple, and blue.
Hopefully this somewhat scientific explanation of fall colors will cause you to understand a little better what went on within trees to bring about an abundance of fall color.
October 8, 2008
Fall is a great time to apply herbicides to control the tougher perennial weeds and the winter annuals that are just starting to germinate. The tough perennials would include weeds like ground ivy and violets. The winter annuals are mainly chickweed and henbit in our area.
The straight 2,4-D that is used on dandelions seems to act like a fertilizer for chickweed and other problem weeds. Combinations that contain 2,4-D, MCPP, and dicamba are rated very effective on chickweed, henbit, red sorrel, purslane, white clover, and others. These combinations are sold under several different trade names. You can find these at most hardware, discount, and lawn and garden stores. Just check the label under active ingredients and check for two long chemical names and dicamba. You can also check to see that it says it will control chickweed and henbit. This group of chemicals is effective in the 50 degree range and up. As with any chemical control, read and follow label instructions very carefully. There will be some cautions on these product labels concerning injury to sensitive plants that you should be aware of. This is because dicamba can drift as a vapor for a few weeks after you apply it if the weather gets hot and sunny.
The mixture with dicamba will control most broadleaf weeds, and the addition of trichlopyr to this mix will even help with violets.
October 7, 2008
October 7, 2008
With continuing weather extremes, such as flooding followed by a month of dry weather, then very cool weather followed by heat followed by a cool August, well things just aren't "normal." These adverse conditions have really taken a toll on our trees. When the entire tree looks like it is dieing, the injury, disease, or insect logically must be affecting the trunk or the roots. These areas would cut off the water supply to the entire tree. Look at the entire tree and compare it to nearby trees. Also consider when the problem started and what changed on the site about that same time. Healthy trees don't suddenly die because they are old. Many below ground reasons may cause tree decline. Drought, flooding, compaction of the root zone, poor soils, planting too deeply, inadequate space for roots and many other things could be involved. Often, diagnosing such a problem is a process of elimination. One of the possibilities more difficult to eliminate is root rot. Most gardeners believe that they cannot possibly know the health of a mature tree's roots.
Cankers on the stems, stem tip dieback, off-color foliage, early fall color and early defoliation are also clues that a tree may be stressed by underground causes. To detect the wood rots and root rots, look for mushroom-like fungi growing at the base of the tree or shrub. In wood rot fungi, the conks (also called shelf fungi or fruiting bodies) may be found growing on the trunk or main branches. These are signs of the disease. The actual fungus is probably growing in or on the roots, or inside the wood. One of the most common examples is Ganoderma root rot, which produces a shelf type of fungal structure at the base of many trees, especially honeylocust. The structure is reddish-brown and appears to have been varnished. Its presence indicates invasion by a root rot. Other fungi may indicate wood rots. Wet weather often triggers the formation of these structures. They could easily be confused with fungi growing on dead organic debris near a tree. If, however, they are growing from the tree itself, they are excellent signs of wood rot or root rot.
No chemicals help a tree in decline. Use approved cultural practices, such as proper watering and fertilizing to improve vitality. Cut out dead branches in the dormant season, fertilize in late fall or early spring and keep traffic off the root system. For very old or large trees, fertilization and watering may have no benefit, but these practices sometimes help the tree survive for years.