Key to Mole Control is Finding Active Run, Not Killing Grubs

Two moles per acre is considered an infestation and ridding a home lawn of moles can seem like a never-winning battle. 

But the odds of success are increased when the right scouting techniques are used according to Brie Menjoulet, an agronomy specialist at the University of Missouri Extension in Hickory County. “No matter what the control method -- granular or gel baits, repellants, or traps -- scouting techniques are the key,” said Menjoulet. 

Moles will feed on earthworms and grubs every two hours, 24 hours a day. Once a mole has eaten the food supply throughout a run, the mole will stop using that run and start a new one.  “Mole traps and baits must be placed in the active runs to be most effective. That makes good scouting essential,” said Menjoulet.

 To find active mole runs, Menjoulet recommends poking a hole through the top of the run. Mark the location with a flag a few inches to the side of the run or by using a landmark that is memorable. “In about 2 hours, check the run and if the hole is repaired or plugged back up, the run is active and will be a good location for baits and traps,” said Menjoulet.

Moles can smell human scents on some types of bait. Using gloves while handling mole baits can help increase product success and reduce possible chemical exposure to the applicator.

 Mole baits are pesticides and can be harmful if not properly used as directed by the label.  “Grub worm pesticides are used to kill grub worms and, unfortunately, can kill up to 70 percent of earthworms as well.  Grub worm pesticides should only be used to kill grub worm infestations, not to control moles by reducing their food supply,” said Menjoulet

Missouri Trees Fall Prey to
Defoliating Insects

From apple to walnut, Missouri trees are falling victim to leaf-eating insects that appear in masses. There are several insects that can cause this type of defoliating damage. Some of them work slowly throughout the canopy of the tree; while others seem to do their work overnight. “Like any other pest-related problem, accurate identification is the first step to determine the proper course of action,” said a University of Missouri Extension horticulture specialist. “Unfortunately, this is not always an easy task. Some of these culprits are easy to spot, others are more elusive.”

Many times, simply identifying the affected plant will indicate the pest. For instance, the walnut caterpillar is a common defoliator of walnut trees, said Marlin Bates. This caterpillar also affects pecan, hickory and other trees. Adults emerge from the soil in late spring and lay masses of eggs on the leaves of the host plant. When the eggs hatch, the young caterpillars begin light feeding on the foliage. These young caterpillars are characterized by their slender, red appearance. As the caterpillars molt, their feeding becomes more destructive. Many times, this is the first sign of their presence because the caterpillars gather on large branches or on the trunk to molt, often leaving their unsightly cast skins behind. After their final molt, they emerge as larger, black and white caterpillars, whose feeding habits are not as damaging as their red predecessors.

“Despite the human reaction these caterpillars can elucidate, their effect on overall tree health is negligible,” said Bates. Most trees can take complete defoliation for two consecutive years before the health of the plant is affected. Also, the caterpillars are often preyed upon by natural enemies.  Finally, recurring infestations of this pest are uncommon. Management is typically reserved for commercial nut production operations or otherwise valuable specimens. “So if you see the walnut caterpillar on your trees this year, the best course of action is most commonly no action,” said Bates. 

Other common defoliators are the May/June beetles and Japanese beetles. The damage from these perpetrators is multi-faceted. Eggs are deposited in the soil at various times throughout the summer months. These eggs give rise to grubs that are known for their destructive feeding on grass roots. Emerging from the soil, the adult form of these insects feed on a wide range of host plants, targeting foliage and fruit. “Japanese beetles are considered voracious eaters of more than 300 species of plants, while May/June beetles are less gluttonous,” said Bates. “The damage done by these beetles is most noticeable when population levels are high. But they’re not always readily identified because they typically escape detection by feeding under the cover of night.”

Again, this damage rarely affects overall tree health unless there are repeated infestations. Controlling these beetles is more important than treatment for walnut caterpillars because they can become perennially problematic. The most common and effective form of control is carried out on the grub-stage of the life cycle, though control of the adult is possible. Soil-moisture management can be an effective means of preventing grub survival in the hot summer months. Several chemicals, with varying lengths of activity, are labeled for use on grubs. Insecticides, if used, should be watered thoroughly into the soil to maximize effectiveness.

“These are just a few of several insects that affect trees in Missouri,” said Bates. “Remember that proper identification of the pest will lead to the most effective management technique.” For more information on these and other insect pests, contact your local University of Missouri Extension office or visit http://extension.missouri.edu.
 

Powdery Mildew Common Problem
on Lilac Bushes

When leaves on a lilac bush start curling and turning brown there are only a couple of common lilac diseases to consider.

However, the most common problem for lilacs in the Ozarks is powdery mildew according to Mark Bernskoetter, president of University of Missouri Extension’s Greene County Chapter of Master Gardeners.

“You can identify this as a white, powdery film over the green leaves on the plant.  It progressively kills the leaves that are affected and the leaves drop to the ground, spreading the spores of this disease,” said Bernskoetter.

There are a few things a gardener can do to counteract the powdery mildew.

One, get rid of the diseased leaves by rake them up and hauling them away.  Another option is to use antifungal sprays to fight the disease. 

“It is also important that lilacs are in a well-ventilated location on your property. Don’t put them in the corner of a wood fence or crowded among a bunch of other plants. Better ventilation will decrease problems from fungal attacks,” said Bernskoetter.

Lilacs are deciduous which means they lose their leaves in the fall.  They will sometimes lose their leaves a little early, especially if the plant was stressed during the summer.

Another common mistake folks make, according to Bernskoetter, is over watering their lilac. This plant only requires about an inch of rainfall per week. 

“If you over water, or if your lilac sits in a low area that has been flooding with our torrential rains this year, the excess moisture can cause the bush to lose its leaves prematurely,” said Bernskoetter.

Continuous “wet feet,” or water soaking around the roots, can kill a lilac. 

“You always want to be sure your lilac receives plenty of sun.  It is common that a nearby tree could be shading the shrub which will stress it, causing early loss of leaves,” said Bernskoetter.

The really sad part is that a lilac with a mildew problem will have fewer blooms next spring

Combating Common Pests of Melons, Cucumbers and Squash

 Cucurbitaceae is one of the most cultivated plant families in the world. From this family, come watermelon, cantaloupe, casaba, honeydew, muskmelon, cucumber, summer squash, winter squash and pumpkins, to name a few. Collectively, these plants, called cucurbits, can be recognized by their vining habits, palmate or five-lobed leaves and male and female flowers on the same plant - each with five fused petals. “In the Midwest, there are a few common insects that can plague these crops,” said a University of Missouri Extension horticulture specialist.

Cucumber Beetle

“Cucumber beetles are the most important insect pest of cucurbits in the United States,” said Marlin Bates. “There are two different species of this pest important in Missouri: the spotted cucumber beetle and the striped cucumber beetle.” The striped cucumber beetle feeds almost exclusively on cucurbits, while the spotted cucumber beetle has a much wider range of hosts. As adults, these beetles appear in the field early and feed on young seedlings. They lay eggs that hatch into root-feeding larvae. When the larvae mature into the next generation of beetles, feeding injury is seen on the foliage again. There are usually three generations of beetles per season. To add to the destructive power of cucumber beetles, they are also notorious for vectoring diseases like bacterial wilt (most common in melons and cucumbers), cucumber mosaic virus and gummy stem blight.

Cucumber beetle control is important in reducing the risk of crop loss. Unfortunately there are few natural enemies that have been identified, so biological control is less than reliable. Row covers can be used to exclude overwintering beetles early in the season, but must be removed during flowering to allow for pollination. Because cucurbits produce a chemical called cucurbitacin that stimulates cucumber beetle and larval feeding, choosing varieties of plants with lower cucurbitacin production can be an effective means of limiting damage. “Choosing for resistance can also be an effective way to avoid some of the vectored diseases associated with cucumber beetles,” said Bates. “The most reliable control of cucumber beetle feeding damage is through the employment of insecticides. Look for products that combine cucurbitacins and small amounts of insecticides in order to preserve beneficial insects.”

Squash Bug

The squash bug is another common pest in the cucurbit garden. Squash bugs suck sap from stems and leaves, leaving behind wilted, decaying plants. These insects prefer pumpkins, watermelons and squash. Even though squash bugs only produce one generation per year, all stages of the life cycle can be found throughout the season. Exclusion at the beginning of the season can be accomplished with row covers. “Again, row covers should be removed at first bloom to avoid pollinator exclusion,” said Bates. Adult squash bugs lay eggs on the undersides of leaves. In smaller gardens these egg masses and the adults can be collected and destroyed by hand. Most insecticides labeled for cucumber beetles are also labeled for squash bugs.

Squash Vine Borer

The squash vine borer is another insect pest of cucurbits. Summer squash, pumpkins and gourds are preferred by this insect while cucumbers and melons typically remain unaffected. As the name implies, the larvae of the squash vine borer literally bore into the stem near the crown. Stems can be girdled and cut off from water and nutrients. Affected vines usually wilt and die, depending on the size of the vine and number of bore holes. Trap crops of Hubbard squash, which are highly susceptible, can be planted to lessen the pressure of squash vine borer on your crop. Hand removal of moths and eggs can be an effective control in small gardens. Again, most insecticides labeled for this pest are also labeled for cucumber beetle and squash bug. Be sure to read the labels carefully to ensure compliance.

For more information on these and other pests of cucurbits, contact your local University of Missouri Extension office, or visit extension.missouri.edu

Pictures courtesy of: DeeAnna Adkins, Content Management Coordinator, Information Architecture Project.

Bagworms Need to be Picked and
Sprayed Right Now!

The bagworm is a real nuisance pest that can cause considerable damage to some plants according to Gaylord Moore, horticulture specialist, University of Missouri Extension. “The most noticeable sign of a bagworm infestation is the presence of silken bags attached to a branch.  The bag resembles a Christmas tree ornament hanging from a limb,” said Moore.

Two types of control are generally effective: chemical applications and hand picking.  The safest and least expensive method of controlling bagworms on small trees and ornamentals is to hand-pick the bags.  But how practical it is to hand pick the bags from the trees (or shrubs) may depend on bagworm numbers and plant size.

 From late May to mid-June, bagworm caterpillars begin emerging from the bags.  Watch your susceptible plants closely for the young larvae. This is the very best time for chemical sprays to be most effective,” said Moore. Chemical control becomes less effective as the season progresses because of the increased size of the larva according to Moore.

Common chemicals effective are carbaryl (Sevin), malathion, acephate (Orthene), and Bacillus thuringiensis (Bt).   

By mid-September the bagworm has completed its development. The adult female bagworm lays between

 500 and 1000 eggs within her bag, after which she dies.  The eggs remain within the bag throughout the winter until they hatch the following spring. 

Four Steps May Help Reduce Impact of Fireblight on Area Fruit Species

Fireblight is a bacterial disease that seems to really be impacting area fruit species like apples and pears according to Gaylord Moore, horticulture specialist, University of Missouri Extension.

Fireblight is most severe in springs when soil moisture is high, when bud and shoot development is rapid, and when frequent rains occur. “Spread of the infection may have occurred during the extreme wet periods the first of May,” said Moore.

When the tree is infected, common symptoms include wilting and die-back of the branch tips which take on a “shepherds crook” appearance. Fireblight can be severe enough to drastically injure or kill the tree.  

According to Moore, four steps may help prevent or reduce the incidence of fireblight in your trees.

One of the best methods to avoid fireblight is to select and plant varieties highly resistant to the disease. “Many good varieties are available and should be planted by the backyard fruit grower,” said Moore.

The second step is chemical control and the timely use of streptomycin, an antibiotic, which can help prevent fireblight. Timing of the application is critical. The first sprays must be applied prior to the sight of infection when the blossom clusters show first tinge of pink. Additional sprays must be applied at early bloom, full bloom, and when all blossoms have fallen.

 The third step is to prune out infected shoots carefully to prevent spreading to healthy shoots. Be certain to prune back about 6 inches into healthy wood and disinfect your pruners with Clorox or alcohol between cuts. “Small pruning cuts to remove infected wood should be done when growth of the tree has slowed,” said Moore.

And finally, remember to avoid too much nitrogen fertilization. Fireblight has been observed to be most severe on vigorously growing trees.

Managing Troublesome Borers on Trees and Shrubs

Larvae of flat and roundhead borers pose a threat to popular tree and shrub plant species in southwest Missouri according to Gaylord Moore, horticulture specialist, University of Missouri Extension.

“Chemical products such as Dursban, Lindane and Cygon, once popular for borer control, are no longer available at lawn and garden centers. Now, effective borer management requires careful planning and thought to produce healthy trees and shrubs,” said Moore.

There are some important points to remember about borer control according to Moore. Borers generally cause little damage to vigorously growing trees.  Plants that are suffering stress from drought or transplanting are prime candidates for borer infestations. “Reducing stress by providing care to trees and shrubs prior to transplanting is important.  Too, planting trees and shrubs into favorable growing environments and providing care such as timely watering is very important to reduce stress,” said Moore.

Chemical control of bores has become more difficult with the loss of Dursban and Lindane for homeowner use according to Moore. “Two or three trunk sprays with Dursban during spring and early summer worked well for borer control as a protectant during egg laying periods of adult borers. These materials prevented the boring activity of the developing larvae before entering the bark of the trees,” said Moore.

There are however, a few systemic chemicals available now that offer some protection and control of damaging borer  “Bayer Advanced Tree and Shrub Insect Control, a product containing imidacloprid, when applied to the soil in advance of borer insect infestation, may be taken up by the tree roots.  Once inside the plant the insecticide offers some protection against intruding borer larvae but little control against existing infestations,” said Moore.

Some products, which contain permethrin as the active ingredient, can be applied directly to the tree trunk to give protection to specific insects such as the ash lilac borer when timed correctly. 

According to Moore, there are some cultural controls for borers that should be standard practices in landscape plantings. “Water newly planted trees carefully to keep the soil ball uniformly moist during the first two growing seasons,” said Moore. “You also need to avoid mechanical damage to the trunks of new trees, wrap them through the winter to prevent trunk scald, fertilize moderately and keep broadleaf herbicides away from tree roots.

Hot Weather Favors Development of Spider Mites in Garden and Landscape Plants

It has been hot and dry, a combination that favors the development and rapid reproduction of the spider mite according to Gaylord Moore, horticulture specialist, University of Missouri Extension.  

“These mites are capable of infesting many garden, tree, shrub and bedding plants. Beans, melons and tomatoes are only a few susceptible vegetable garden crops,” said Moore. Annual flowers -- such as marigolds and petunias -- are quite vulnerable. Common landscape plants affected by mites include azalea, cotoneaster, Alberta spruce and roses.

Mites damage plants by sucking contents from leaf tissue. The initial damage appears as a stippling of light dots on the leaves. As feeding continues, the leaves turn yellow or bronze in color and drop off. Because spider mites are very small, they can be difficult to see on plants. “Check for spider mites by holding a piece of white paper underneath a branch and shake or tap the branch sharply. If mites are present, some will be dislodged from the leaves and fall onto the paper where they will be seen as tiny moving specks,” said Moore.

 Predator insects often take care of spider mite populations. But, if pesticide treatments are needed, confine the applications to those plants most seriously infested to help conserve the natural enemies. “Spider mites flourish on plants under stress. Keeping plants well watered and fertilized can help to minimize the stress,” said Moore.

Mite populations can also be reduced by forcefully spraying plants with water, especially on the undersides of leaves, to break up the webs and wash the mites off. Insecticides such as Kelthane (dicofol), malathion or insecticidal soaps are common mite controls with vegetable crops. Acephate (Orthene) works with bedding plants, trees and shrubs. Coverage on the undersides of the leaves is essential and repeated applications may be necessary.

Spreader-stickers Can Help Spray Solutions Spread More Evenly on Leafs and Fruit

Most gardeners have heard about spreader-stickers, adjuvants and surfactants, but what do they do? Basically, a “sticker” -- like dishwashing soap -- can help the spray solution spread evenly on the leaf and fruit. Spreader-stickers also increase the solution penetration of the contact material on insects.

“That means having a spreader-sticker available makes the total effectiveness of the pesticide increase,” said Gaylord Moore, horticulture specialist with University of Missouri Extension.Spreader-stickers will also give longer residual of the pesticide by reducing the breakdown from sunlight and rain and prolonging the presence.

What about the effectiveness of dishwashing soap to assist the fungicide? “A small squirt of dishwashing soap will break up the surface tension of the water and provide a better coverage on the waxy leaves and fruit surface of many plants,” said Moore. However, the longevity of the product may not be increased.

Surfactant or spreader-stickers are inexpensive and available in most lawn and garden centers. When mixed with most liquid pesticides the overall performance will be enhanced. “The label on your pesticide may give specific information about the use of spreader-stickers. Some may recommend them while others may not,” said Moore.

No matter, Moore says to be sure and read the label because some products may already have these spreader-sticker materials incorporated in the formulation.    

Area Fruit Trees Being Impacted by Peach Tree Curl

      Are the leaves of your peach trees suddenly puckering or blistering? In the last week, Extension specialists have been swamped with questions from people desperately trying to figure out what is happening to their peach trees.   “The good news is, we can tell you what it is – Peach Leaf Curl, the bad news is, at this point, there is not much that can be done,” said Wesley Tucker, agriculture and rural development specialist, University of Missouri Extension.

      Peach Leaf Curl is caused by a fungus called Taphrina deformans. The spores of this fungus are relatively resistant to adverse weather conditions and can remain lodged on the surface of twigs for two years or more.   The only way to control Peach Leaf Curl is to apply a fungicide during the dormant period. Applications can be made at leaf drop in the fall or in mid to late winter before bud swell. “Once the fungus enters the leaf there is really nothing that can be done to control the disease. If the infection of leaf curl is severe enough it can weaken the tree,” said Tucker.

     Although you may not be able to control the disease, there are some steps the owner of a peach tree can take. First, thinning fruits to reduce the demand on the remaining leaves may be required. According to Tucker, watering the tree when it turns dry and applying nitrogen fertilizer to severely infected trees will also help improve their vigor.

     “Peach Leaf Curl is another one of those diseases that by the time you know you have it, it’s too late to do anything about. That’s why we give out so many fruit spray schedules to remind you when to spray and for what - ahead of time,” said Tucker.

     Fruit spray schedules, and information about Peach Leaf Curl, are available from your local county University of Missouri Extension Center or online at http://extension.missouri.edu.
 

Take Steps to Minimize Attraction of Termites to Landscape Mulches

     A common concern among homeowners is whether landscape mulches attract or harbor termites.  “There is some risk, so a homeowner is advised to take steps to minimize attraction,” said Gaylord Moore, horticulture specialist, University of Missouri Extension.

    Researchers have documented that subterranean termites are capable of consuming certain types of mulch, including pine bark, pine straw, ground yard waste and cypress mulch.   “The warm, moist conditions found under mulch, whether organic or inorganic, tend to be favorable for termite exploration, tunneling and feeding,” said Moore.

      Are barks or organic mulches more or less attractive to termite activity than others? According to Moore, there is little difference in the termite attraction or consumption of various bark mulches.
“Initially, there may be some differences, but as the mulches age and continue to decompose little differences are detected,” said Moore.

What about using the gravel mulches in the landscape instead?  “According to field research, sustained termite activity was actually higher under pea gravel mulch than under pine and hardwood bark mulch. The favorable moist environment created by the gravel is thought to be the attraction,” said Moore.

     What steps can the average homeowner take to minimize the attraction of termites when mulches are used in landscaping around the house?  For starters, Moore recommends avoiding thick layers of mulch near the base of the foundations.   “The most important practice for detecting a termite infestation in a home is to leave at least a foot of concrete foundation exposed so mud termite tunnels can be easily seen during inspection,” said Moore.

Basic Management Can Help Reduce
Tomato Blight

Tomatoes are the number one crop planted in the vegetable garden according to Gaylord Moore, horticulture specialist, University of Missouri Extension.

“While tomatoes are popular and easy to grow, both the home gardener and commercial grower find it challenging to maintain productivity throughout the growing season,” said Moore.

Diseases such as Septoria leaf spot and early blight affect the lower portion of the tomato plant and shorten productivity. Without effective control, the disease will start at the bottom of the plant and work to the top until plants completely defoliate.

Environmental conditions play a role in presence and severity of certain diseases. Abundant rainfall and high humidity pose a threat to severe blight conditions. As a result, blight may be worse some years than others.

Little resistance to blight is available through variety selections, so proper cultural management techniques are important for control.

“Disease management must start early in the season. Once you have the problem, control is difficult,” said Moore. “There are some management practices that can help control blight.”

Site and ground selection. If possible, a three to four year rotation with crops outside of the Solanacea family should be followed. Potatoes, tomatoes, peppers, and eggplant are within the same family and these crops should not be included in the rotation planting cycle.

Fertile soil, disease free plants and observing proper planting dates should be followed can help manage blight. “Plants stressed prior to planting or following planting may lead to disaster. Home gardeners should try and avoid planting tomatoes before the soil has warmed to avoid stunting and plant stress. A healthy plant will better resist some diseases,” said Moore.

Avoid ground contact with plant foliage.“For best results, stake tomato plants and mulch underneath them to reduce the incidence of blight transfer from the soil to the plant. Avoid mulching tomatoes until the soil has thoroughly warmed to allow for optimum growth,” said Moore.For the home gardener wheat straw is an excellent mulch source. Blights are soil borne diseases and anything that inhibits the transfer of spores from the ground to the plant will help increase the chances for control, according to Moore.

Good air circulation around the plants (aided by proper spacing and pruning) will reduce blight infections. If room allows, 30 inches between staked indeterminate plants is suggested. “In my opinion, staked versus caged tomatoes will be less pronged for disease. Staked tomatoes are more accessible to proper pruning which removes excess foliage that may hinder air circulation,” said Moore.Basic pruning is the removal of side shoots or suckers when they are three to four inches long.

Avoid overhead irrigation during the evening. “Better yet, trickle irrigation or bottom irrigation will help avoid moisture contact with the leaves reducing conditions for ideal disease development,” said Moore.

If all procedures fail to control blight, be prepared to replant transplants about the middle of July for a fall crop. Typical summer conditions of heat and dry weather result in less incidence of disease thus providing productive plants until frost.

Chemical fungicide application is often needed but application timing is crucial. For the commercial grower, Quadris will provide the best control of foliar disease when alternated with chlorothalonil or mancozeb. Home gardeners may use chlorothalonil (Daconil), maneb, or mancozeb. “Nothing guarantees 100 percent control. But following all of the suggested recommendations for good management and cultural practices is a giant step in the right direction,” said Moore.(back to top)

Seven Factors Help Reduce Diseases that Plague Tomatoes

While tomatoes are popular and easy to grow, both the home gardener and commercial grower find it challenging to maintain productivity throughout the growing season.

Diseases such as Septoria leaf spot and early blight affect the lower portion of the tomato plant and shorten productivity.

Environmental conditions play a role in presence and severity of certain diseases. Abundant rainfall and high humidity pose a threat to severe blight conditions.

Little resistance to blight is available through variety selections, so proper cultural management techniques are important for control.

“Disease management must start early in the season. Once you have the problem, control is difficult,” said Patrick Byers, horticulture specialist, University of Missouri Extension.

1. One key factor is site and ground selection. If possible, a three to four year rotation with crops outside of the Solanacea family should be followed. Potatoes, tomatoes, peppers, and eggplant are within the same family and these crops should not be included in the rotation planting cycle.
    

2. To help manage blight, disease free plants should be planted in fertile soil based on the proper planting dates. “Plants stressed prior to planting or following planting may lead to disaster,” said Byers.
    

3. It is important to avoid ground contact with plant foliage. “Stake tomato plants and mulch underneath them to reduce the incidence of blight transfer from the soil to the plant,” said Byers.   For the home gardener wheat straw is an excellent mulch source. Blights are soil borne diseases and anything that inhibits the transfer of spores from the ground to the plant will help increase the chances for control, according to Byers.
    

4. Good air circulation around the plants (aided by proper spacing and pruning) will reduce blight infections. If room allows, 30 inches between staked indeterminate plants is suggested. Basic pruning is the removal of side shoots or suckers when they are three to four inches long.
    

5. Avoid overhead irrigation during the evening. Trickle irrigation or bottom irrigation is best to avoid moisture contact with the leaves reducing conditions ideal for disease.
    

6. If all procedures fail to control blight, be prepared to replant transplants about the middle of July for a fall crop. Typical summer conditions of heat and dry weather result in less incidence of disease thus providing productive plants until frost.

7. Chemical fungicide application is often needed but application timing is crucial. Home gardeners may use chlorothalonil (Daconil) at seven to 14 day intervals.

     For more information:  Guide sheet 6203, “Common Diseases in the Home Garden” is also available online at extension.missouri.edu.

Control Problem Plant Pests 
With Dormant Sprays

Signs that spring is around the corner are evident with the activity of spring bulbs, greening grass and the swelling of buds on trees and shrubs.

Soon, deciduous plants will be breaking dormancy with the emergence of new leaves and flowering plants will show off their beauty with brilliant colors celebrating the start of spring.

But before plants have become fully active, certain problem tree and shrub pests may need to be suppressed by applying dormant or horticultural oils according to Gaylord Moore, horticulture specialist, University of Missouri of Missouri Extension.

Dormant or horticulture oils are usually highly refined petroleum oils combined with an emulsifying agent. These oils are formulated to mix with water and sprayed directly on the plant.

"Good coverage is essential for pest control," said Moore. "Oils help manage certain problems like scales, aphids, and mites on fruit trees, some shade trees and woody ornamental plants."

At this time of year, oils are most effective on scale insects and some insects in the adult, larvae and egg stage. But best of all, according to Moore, oils get the job done without leaving a mess.

"Oils block the air holes (spiracles) through which insects breathe, causing them to die from asphyxiation. But best of all, oils pose few risks to people, natural enemies of insects or the environment," said Moore.

In fact, toxicity from these oils is minimal, at least compared to alternative pesticides, and oils quickly dissipate through evaporation, leaving little residue.

" Horticulture oils may also be applied during the growing season. Oils now are so highly refined they pose little threat to the health of most plants even with green foliage," said Moore.

This is one precaution that Moore offers. When applying oils during dormancy watch the air temperatures.

"Do not apply oils during freezing weather. This can cause the emulsion to break down and produce uneven coverage. It is best if you pick a stretch of above freezing weather in the 40’s before applying the oil," said Moore. (back to top)

Courthouse, 1 N. Delaware Butler, MO 64730 Phone: 660-679-4167   Fax:  660-679-4697 Bates County is part of the West Central Region of University of Missouri Extension
		Bates County University of Missouri  Extension Center BatesCo@missouri.edu Updated 05/26/09
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