With many municipalities and tree service companies having wood chippers, gardeners often are able to get chips free. We are sometimes asked our opinion about whether these make a good mulch.    
          
Some people have heard that these chips will tie up nitrogen so that the garden plants won't grow as well. If wood chips are used as a mulch, there is no cause for concern. However, if the chips are mixed with the soil, there can be a problem during the breakdown process. The microorganisms that break down the chips need a certain amount of nitrogen during the process. With most green material, there is enough nitrogen in the material itself to meet the needs of the microorganisms.  However, nitrogen levels in wood chips are so low, the microorganisms must borrow it from the surrounding soil. This results in less nitrogen being available to the plants. However, when the raw organic material has been digested, the microorganisms die and release the nitrogen. Therefore, the nitrogen is not lost but is simply unavailable for plant use for a period of time. Again, this is only a concern if the wood chips are mixed into the soil. There is no problem with nitrogen tie-up if the chips are used as a mulch.  
      
However, one point should be kept in mind. These chips can be used by foraging termites as a bridge to homes and other structures. Termites are light and heat sensitive and will not bother the chips themselves if they are 3 inches deep or less. Therefore, watch the depth of these chips near the house or other buildings.  Also leave a bare area several inches wide next to the house so that any termite activity is noticeable. 
​
When applying mulch around trees, do not mound the mulch so it looks like a volcano.  Remember that roots need oxygen as well as moisture and the movement of both can be hindered by a deep layer of mulch.  A depth of about 3 inches is about right.  (Ward Upham) 

With many municipalities and tree service companies having wood chippers, gardeners often are able to get chips free. We are sometimes asked our opinion about whether these make a good mulch.      
   
 Some people have heard that these chips will tie up nitrogen so that the garden plants won't grow as well. If wood chips are used as a mulch, there is no cause for concern. However, if the chips are mixed with the soil, there can be a problem during the breakdown process. The microorganisms that break down the chips need a certain amount of nitrogen during the process. With most green material, there is enough nitrogen in the material itself to meet the needs of the microorganisms.  However, if nitrogen levels in wood chips are so low, the microorganisms must borrow it from the surrounding soil. This results in less nitrogen being available to the plants. However, when the raw organic material has been digested, the microorganisms die and release the nitrogen. Therefore, the nitrogen is not lost but is simply unavailable for plant use for a period of time. Again, this is only a concern if the wood chips are mixed into the soil. There is no problem with nitrogen tie-up if the chips are used as a mulch.      

 However, two other points should be kept in mind. These chips can be used by foraging termites as a bridge to homes and other structures. Termites are light and heat sensitive and will not bother the chips themselves if they are 3 inches deep or less. Therefore, watch the depth of these chips near the house or other buildings.  Also leave a bare area several inches wide next to the house so that any termite activity is noticeable. 
​
The second concern regards mulching trees.  Do not mound mulch around the trunk of the tree as it can damage it.  Leave a few inches of bare soil so the trunk can remain dry.  (Ward Upham) 

​Now is a good time to mulch garden vegetables if you haven’t done so already. Mulches provide several benefits including weed prevention, reduced watering due to less evaporation and cooler soils that enhance root growth. Straw and hay are popular mulches in Kansas due to their availability. However, both may contain weed seeds that will germinate if the thatch layer is not thick enough. Grass clippings can also be used if the lawn has not been treated with weed killers. Add only a thin layer of clippings at a time and allow to dry for 2 to 3 days before adding more. A thick layer will form a mold that is almost impervious to water. A mulch layer one-half to three-quarters inch thick is about right for grass clippings but hay or straw should be at a depth of 2 to 4 inches. (Ward Upham)

July 26            K-State Bedding Plant Field Day, Olathe  http://www.eventbrite.com/e/k-state-flower-field-day-tickets-26105824223
 
July 30            K-State Research & Extension Center Horticulture Field Day, Olathe http://www.johnson.k-state.edu/lawn-garden/horticulture-field-day.html
 
August 4         Kansas Turfgrass Field Day, Manhattan https://turffieldday.eventbrite.com

Bermudagrass can make a nice lawn if you don't mind its invasiveness and short growing season. But many people dislike both these characteristics. Warm-season grasses, such as bermudagrass, zoysiagrass and buffalograss, green up later than cool-season grasses such as tall fescue and Kentucky bluegrass. They also go dormant earlier in the fall, which can make a lawn unattractive.
 
Bermuda that invades a cool-season lawn will be brown during much of the spring and fall while the tall fescue portion of the lawn is green. Bermuda is much more drought and heat resistant than cool-season grasses, so it will take over a cool-season lawn during the summer months if it is in full sun.
 
So, how do you control bermudagrass that has invaded a cool-season lawn? Research conducted in 1996 showed that glyphosate (Round-up, Kleen-up, Killzall, Kleeraway) is the best herbicide for the job. Glyphosate is a nonselective herbicide and will kill everything— including tall fescue or Kentucky bluegrass. Therefore, you will need to reseed treated areas. In our study, we applied a 2% solution of glyphosate on July 15 and again on August 15 on a bermudagrass plot that was more than 15 years old. More than one year later, we saw no regrowth. Glyphosate works best if bermuda is growing well. The better the bermudagrass is growing, the more chemical is taken up and pushed into the roots. Water and fertilize if needed to get it going.
 
Spray about the middle of July (or when the bermuda is growing well). Use glyphosate (2% solution). Wait two weeks and scalp the lawn (mow as low as possible and remove clippings.) This will prevent dead grass from covering any bermuda that starts to recover. Wait another two weeks and spray again with glyphosate if there is any green. Wait two more weeks and reseed. (Ward Upham)

Heavy fruit loads this season may cause limbs to break if they are not given extra support. As fruits increase in size, the additional weight on individual branches may be substantial. One-inch thick boards can be used to prop up limbs.
 
Here's how. Cut a "V" on the top edge of the board on which the limb will rest so that it doesn't slip off. Long limbs that are heavily loaded with fruit may need a prop in the center and another to support the outer part of the limb. A plastic belt-like material that is about 2 inches wide may also be used. This can be tied to a heavily loaded limb, then to a large diameter limb above for support. Where a large limb is used for support, it is good to have it supporting limbs on opposite sides so the weight is balanced.
 
Another solution is to wrap a tape or belt material around the tree in a spiral to prevent limbs from bending until they break. Heavy twine may be used, but it should be removed when the fruit is picked or soon after so it does not cut into the bark on the limb.
 
Check trees regularly, up to two times a week during the last month the fruit are maturing. You will find additional limbs that need support. Tending to the heavily loaded tree limbs will reduce the number of broken limbs and help keep a balance of the fruiting wood in your tree. Next year, prune long, weak branches back to a side branch to help prevent this problem. (Ward Upham)

The extreme heat and drought can cause some rarely seen phenomenon. Dennis Patton, our Horticulture Agent in Johnson County has had several reports of apparently sound branches breaking out of what appeared to be a healthy trees (primarily oaks) recently. There was an article written by Richard Harris, the author of a standard Arboriculture text that describes this phenomenon. His observations are summarized below.
 
This type of damage has been reported on both landscape and forest trees. The landscape trees were found in irrigated and unirrigated situations.
 
These limbs can be huge; up to 3 feet in diameter. Most often the break occurs 3 to 12 feet from where the branch attaches though at times the branch may break at the attachment. Though breaks do occur in decayed wood, often the broken branch shows no sign of weakness or decay.

No firm explanation of a cause has been established though buildup of pressure within the branch has been noted.  In some cases, the branch seems to explode and then drop. The reason for this pressure buildup is unclear though several ideas have been put forth.
 
Certain species are more susceptible to this condition including oaks, poplars, cottonwood, willows, ash, sycamore and Japanese Pagodatree. You will find more detail in Richard Harris’ article at  http://artistictreeworks.com/harris.html
 
Be cautious around these trees during hot, calm weather. Hopefully, the cooler weather we had last week will reduce the changes of this happening. (Ward Upham)

Hornworms are the largest larval insect commonly seen in the garden. Though usually seen on tomato, they can also attack eggplant, pepper, and potato.
 
The larval stage of this insect is a 3 ½- to 4-inch long pale green caterpillar with five pair of prolegs and a horn on the last segment. The two most common hornworms are the tobacco hornworm (seven diagonal white stripes and, most commonly, a red horn) and the tomato hornworm (v-shaped markings with a horn that is often blue or black).
 
The adult of the tobacco hornworm is the Carolina sphinx moth. The five-spotted hawk moth is the adult of the tomato hornworm. Both moths are stout-bodied, grayish-colored insects with a wing spread of 4 to 5 inches.
 
The larva is the damaging stage and feeds on the leaves and stems of the tomato plant, leaving behind dark green or black droppings. Though initially quite small with a body about the same size as its horn, these insects pass through four or five larval stages to reach full size in about a month. The coloration of this larva causes it to blend in with its surroundings and is often difficult to see despite its large size. It eventually will burrow into the soil to pupate. There are two generations a year.
 
This insect is parasitized by a number of insects. One of the most common is a small braconid wasp. Larva that hatch from wasp eggs laid on the hornworm feed on the inside of the hornworm until the wasp is ready to pupate. The cocoons appear as white projections protruding from the hornworm's body. If such projections are seen, leave the infected hornworms in the garden. The wasps will kill the hornworms when they emerge from the cocoons and will seek out other hornworms to parasitize.
 
Handpicking is an effective control in small gardens. Bt (Dipel, Thuricide), spinosad (Conserve; Borer, Bagworm, Leafminer & Tent Caterpillar Spray; Colorado Potato Beetle Beater Conc; Captain Jack's Dead Bug Brew, Monterey Garden Insect Spray), cyfluthrin (Bayer Vegetable & Garden Insect Spray) and other insecticides may also be used to control hornworms. (Ward Upham)

If you notice leaves disappearing from walnut trees, it may be walnut caterpillars. Walnut caterpillars attack primarily black walnut, pecan, and several species of hickory trees, but may also attack birch, oak, willow, honey locust, and apple trees.
 
Walnut caterpillars overwinter as pupae underground beneath host trees. In late spring, moths emerge and deposit egg clusters on lower leaves. By the end of June, newly emerged and gregarious larvae skeletonize leaves. Larger hairy, brick-red larvae consume greater amounts of leaf tissue, and nearly matured gray larvae devour entire leaves, including petioles.
 
As mentioned earlier, walnut caterpillars are gregarious. In other words, they feed in groups. A single tree may contain several groups.  When disturbed, larvae arch their bodies in what looks like a defensive move. Larvae crowd together on the lower parts of trees to molt and leave an ugly patch of hairy skins. Mature larvae, 2 inches long, descend or drop to the ground where they enter the soil to pupate. A second generation occurs soon, creating the overwintering pupae.
 
Removing leaves with egg masses is an effective way to control walnut caterpillars. This may be impractical with large trees or when too many infested leaves are present. Bands of Tree Tanglefoot pest barrier may be used to snare larvae as they migrate to main branches or the trunk to molt. Insecticides such as spinosad (Conserve; Captain Jack’s Dead Bug Brew; Borer, Bagworm, Leafminer and Tent Caterpillar Spray) permethrin (numerous trade names) malathion or cyfluthrin (Tempo, Bayer Vegetable and Garden Insect Spray) may provide the most practical means of control. (Ward Upham)

There was a study done in 2005 by Ohio State University that compared the effectiveness of various biorational and natural products to more traditional pesticides. Squash bug was one of the insects that was a target organism. What was interesting is that certain products were more effective at different life stages. The researchers compared the effectiveness of products on young nymphs, old nymphs and adults. Following are the results for squash bug:
 
 
 
Life Stage            Most Effective          Moderately Effective                   Least Effective

Young Nymphs        Spinosad                               Carbaryl                                                           Garlic
                                                                                          Pyrethrins                                                       Neem Oil
                                                                                          Permethrin

Old Nymphs              Spinosad                            Permethrin                                                       Pyrethrins
                                                                                                                                                                      Carbaryl

Adults                         Cyhalothrin                        Esfenvalerate                                                  Spinosad
                                      Cyfluthrin                                                                                                         Permethrin
                                      Pyrethrins                                                                                                          Carbaryl
 
Carbaryl - Sevin
Cyfluthrin - Bayer Vegetable & Garden Insect Spray
Esfenvalerate - Monterey Bug Buster II
Cyhalothrin - Bonide Beetle Killer; Spectracide Triazicide
Permethrin - Bonide Eight Garden Dust; Bayer Complete Insect Dust; Hi-Yield Garden, Pet & Livestock Dust
Pyrethrins - Monterey Bug Buster-O; Fertilome Quik-Kill Home, Garden & Pet Spray
Spinosad - Fertilome Borer, Bagworm, Leafminer & Tent Caterpillar Spray; Bonide Captain Jack’s Dead Bug Brew; Bonide Colorado Potato Beetle Beater
 
To see the complete study, go to http://entomology.osu.edu/welty/pdf/VegIPMReport2005.pdf (Ward Upham)
 
Contributors:  Ward Upham, Extension Associate

Bermudagrass can make a nice lawn if you don't mind its invasiveness and short growing season. But many people dislike both these characteristics. Warm-season grasses, such as bermudagrass, zoysiagrass and buffalograss, green up later than cool-season grasses such as tall fescue and Kentucky bluegrass. They also go dormant earlier in the fall, which can make a lawn unattractive. Bermuda that invades a cool-season lawn will be brown during much of the spring and fall while the tall fescue portion of the lawn is green. Bermuda is much more drought and heat resistant than cool-season grasses, so it will take over a cool-season lawn during the summer months if it is in full sun.

So, how do you control bermudagrass that has invaded a cool-season lawn? Research conducted in 1996 showed that glyphosate (Round-up, Kleen-up, Killzall, Kleeraway) is the best herbicide for the job. Glyphosate is a nonselective herbicide and will kill everything— including tall fescue or Kentucky bluegrass. Therefore, you will need to reseed treated areas. In our study, we applied a 2% solution of glyphosate on July 15 and again on August 15 on a bermudagrass plot that was more than 15 years old. More than one year later, we saw no regrowth. Glyphosate works best if bermuda is growing well. The better the bermudagrass is growing, the more chemical is taken up and pushed into the roots. Water and fertilize if needed to get it going.

Spray about the middle of June (or when the bermuda is growing well). Use glyphosate (2% solution). Wait two weeks and scalp the lawn (mow as low as possible and remove clippings). This will prevent dead grass from covering any bermuda that starts to recover. Wait another two weeks and spray again with glyphosate if there is any green. Wait two more weeks and reseed. (Ward Upham)

Heavy fruit loads this season may cause limbs to break if they are not given extra support. As fruits increase in size, the additional weight on individual branches may be substantial. One-inch thick boards can be used to prop up limbs.

Here's how.  Cut a "V" on the top edge of the board on which the limb will rest so that it doesn't slip off. Long limbs that are heavily loaded with fruit may need a prop in the center and another to support the outer part of the limb. A plastic belt-like material that is about 2 inches wide may also be used. This can be tied to a heavily loaded limb, then to a large diameter limb above for support. Where a large limb is used for support, it is good to have it supporting limbs on opposite sides so the weight is balanced. Another solution is to wrap a tape or belt material around the tree in a spiral to prevent limbs from bending until they break. Heavy twine may be used, but it should be removed when the fruit is picked or soon after so it does not cut into the bark on the limb.

Check trees regularly, up to two times a week during the last month the fruit are maturing. You will find additional limbs that need support. Tending to the heavily loaded tree limbs will reduce the number of broken limbs and help keep a balance of the fruiting wood in your tree. Next year, prune long, weak branches back to a side branch to help prevent this problem. (Ward Upham)

Blackberry and raspberry fruit will often develop white or tan drupelets on the berry. Though we are not completely sure of the cause, two commonly given reasons are stinkbug damage and sunscald.  Damage has been attributed to stinkbugs if the pattern of off color (not white) drupelets is random. Stinkbug damage is caused by the insect feeding on the blackberry receptacle and injuring drupelets on either side. Sunscald damage will be on the side of the fruit exposed to the sun and has several drupelets in a small area being affected.

Neither condition affects the eating quality of the fruit unless the stink bug releases the “stink” with which it is associated rendering the fruit inedible. By the time damage is seen, it is too late for control. (Ward Upham)

Potatoes are ready to harvest when the vines are about half dead. Potatoes dug too early have tender skins and are easily bruised. Delaying digging will allow the soil to heat because it is no longer shaded by foliage. High soil temperatures can lead to sprouting potatoes. Allow potatoes to "set" by keeping them in a shady, dry location for a day or so. Move them to a cool, moist environment such as a cellar or cool basement for longer storage. (Ward Upham)

Japanese beetles have become a firmly established pest species in portions of Kansas. Potential damage is twofold. Most commonly, Japanese beetles indiscriminately feed on nearly 300 plant species including fruits, vegetables, agronomic and forage crops, ornamentals, trees and shrubs. Often times, host plants are literally covered with the gregarious beetles which rapidly consume any and all foliage and floral plant tissue. A second type of damage is associated with the “white grub” larval stage as a potential turf pest.

While some individuals prefer to calculate/record accumulated Growing Day Degrees 50 as a method to predict the initial yearly appearance of Japanese beetles, one can more easily set out traps baited with the JB pheromone and floral lure. The bonus is that this also tells an individual that JB actually are “in-the-neighborhood” as evidenced by their being captured.

First 2015 reports of JB captures: Desoto June 9; Manhattan June 15; Topeka June 16. Look for their numbers to rapidly increase. People concerned with JB feeding on landscape plants need to be vigilant in inspecting plants for the presence of JB. If present and if in damaging numbers, corrective actions should be undertaken.

Refer to K-State Research and Extension Publication MF3151 – Japanese Beetle (Bob Bauernfeind)

If you notice leaves disappearing from walnut trees, it may be walnut caterpillars. Walnut caterpillars attack primarily black walnut, pecan, and several species of hickory trees, but may also attack birch, oak, willow, honey locust, and apple trees.      

Walnut caterpillars overwinter as pupae underground beneath host trees. In late spring, moths emerge and deposit egg clusters on lower leaves. By the end of June, newly emerged and gregarious larvae skeletonize leaves. Larger hairy, brick-red larvae consume greater amounts of leaf tissue, and nearly matured gray larvae devour entire leaves, including petioles.

As mentioned earlier, walnut caterpillars are gregarious. In other words, they feed in groups. A single tree may contain several groups.       

When disturbed, larvae arch their bodies in what looks like a defensive move. Larvae crowd together on the lower parts of trees to molt and leave an ugly patch of hairy skins. Mature larvae, 2 inches long, descend or drop to the ground where they enter the soil to pupate. A second generation occurs soon, creating the overwintering pupae.

Removing leaves with egg masses is an effective way to control walnut caterpillars. This may be impractical with large trees or when too many infested leaves are present. Bands of Tree Tanglefoot pest barrier may be used to snare larvae as they migrate to main branches or the trunk to molt. Insecticides such as spinosad (Conserve; Captain Jack’s Dead Bug Brew; Borer, Bagworm, Leafminer and Tent Caterpillar Spray) permethrin (numerous trade names) malathion or cyfluthrin (Tempo, Bayer Vegetable and Garden Insect Spray) may provide the most practical means of control. (Ward Upham)

The two-lined spittlebug derives its name from the white, frothy" spittle" the nymphs produce. Adults are large, black leafhoppers about 1/3-inch long with two red stripes that go crosswise across the back. The eyes and abdomen are bright red. Though the nymphs resemble the adults, they are smaller and wingless. Color varies from yellow to white to orange but the eyes are always red.

Spittlebug nymphs suck plant juices like aphids, but they remove so much water and carbohydrates that excess fluid is produced. They cover themselves with this fluid and then produce the spittle by bubbling air from the tip of the abdomen into the liquid. The spittle mass helps protect the nymphs from drying and predators.

Spittlebugs normally do not achieve high enough populations to cause damage. If they do, forcefully hosing the plants several times should achieve the level of control needed. (Ward Upham)

There have been many concerned calls to state specialists and county agents this spring and summer about cupped and curled leaves on landscape trees and what is causing it. Also homeowners want to know if the tree will die from the damage or grow out of it. While there are some insects that can cause these symptoms (margin or vein pocket gall on pin oaks, or high aphid populations on young leaves), the most common cause is herbicide drift, or volatilization. The usual culprit is a phenoxy-type herbicide, of which 2,4-D is the most commonly used. Drift is caused when tiny spray droplets are carried by wind to off-site and off-target plants. This type of damage commonly occurs when an agricultural field is close to a residential landscape, and drift reduction methods are not followed, like accounting for the wind, and using uniform droplet or large droplet nozzles, and lower pressures.

Volatilization is a different problem altogether, and almost impossible to trace back to a source. Some herbicides, particularly the ester formulations of 2,4-D and related chemicals are prone to vaporize, and move off site. The conditions that promote volatilization (high humidity, low wind speeds) are different than conditions that promote drift (high wind speeds). Sometime the damage is caused by the homeowner themselves, spraying for weeds in their lawn.

The various oak species are quite sensitive to herbicide exposure, especially when the new leaves are just expanding.  It is the time-sensitive nature of exposure that will lead to normal leaves being found on the same twig as badly distorted leaves. Redbud is another tree species that is very sensitive to herbicides. However, the presence of twisted and cupped leaves on your tree does not mean that tree will die. If most of the leaves remain green, and if new leaves emerge without symptoms, the exposure was not severe enough to do any real harm. This is a recurring problem, due to agriculture being the dominant land use in Kansas, but fortunately the damage, although striking visually, is usually just superficial, and the tree will grow out of it just fine.  (Charlie Barden)

Contributors: Charlie Barden, Extension Forester, Bob Bauernfeind, Entomologist; Ward Upham, Extension Associate

To view Upcoming Events: http://tinyurl.com/fswqe          

Watch for rust on hollyhock. This is the most common disease on hollyhock and can cause serious injury as leaves are progressively killed through the summer. Look for yellow spots on the surface of the leaves and orangish to brown pustules on the underside. Infections can also take place on stems and green flower parts.

The first line of defense is to remove all hollyhock stalks, leaves and other debris in the fall and destroy them. Remove any infected foliage you see now. Just be sure the foliage is dry so you don’t spread the
disease. Continue to remove diseased leaves as soon as they show spots. Try using a fungicide such as sulfur or myclobutanil (Immunox or Immunox Plus) to protect healthy foliage. Note that sulfur may burn leaves if the air temperature is over 85 degrees within 24 hours of application. Follow label directions for timing and rate. (Ward Upham)

Many gardeners look forward to harvesting new potatoes this time of year. New potatoes are immature and should be about the size of walnuts.  Pull soil away from the base of the plants to see if the tubers are the desired size. If they are, dig entire plants and allow the skins of the  exposed tubers to dry for several hours before gathering. These young potatoes are very tender and prone to the skin “slipping” unless they are given a few hours to dry. Even then these immature potatoes will not store well. Red-skinned varieties are often preferred as they are the earliest to produce. (Ward Upham)

Now is a good time to mulch garden vegetables if you haven’t done so already. Mulches provide several benefits including weed prevention, reduced watering due to less evaporation and cooler soils that enhance root growth. Straw and hay are popular mulches in Kansas due to their availability. However, both may contain weed seeds that will germinate if the thatch layer is not thick enough. Grass clippings can also be used if the lawn has not been treated with weed killers. Add only a thin layer of clippings at a time and allow to dry for 2 to 3 days before adding more. A thick layer will form a mold that is almost impervious to water. A mulch layer one-half to three-quarters inch thick is about right for grass clippings but hay or straw should be at a depth of 2 to 4 inches. (Ward Upham)

Though tomatoes need to be fertilized to yield well, too much nitrogen can result in large plants with little to no fruit. Tomatoes should be fertilized before planting and sidedressed with a nitrogen fertilizer three times during the season.The first sidedressing should go down one to two weeks before the first tomato ripens. The second should be applied two weeks after the first tomato ripens and the third one month after the second. Common sources of nitrogen-only fertilizers include nitrate of soda, urea, and ammonium sulfate. Blood meal is an organic fertilizer that contains primarily, but not exclusively, nitrogen.
Use only one of the listed fertilizers and apply at the rate given below.

If you cannot find the above materials, you can use a lawn fertilizer that is about 30 percent nitrogen (nitrogen is the first number in the set of three) and apply it at the rate of 1/3 pound (3/4 cup) per 30 feet of row. Do not use a fertilizer that contains a weed killer or weed preventer. (Ward Upham)

* Remove fruit from heavily loaded apples and peaches (if the flower buds weren’t killed by frost) to improve fruit size and prevent limbs from breaking. Apples should be spaced every 4 inches and peaches every 6 to 8. Note that is an average spacing. Two fruit can be closer together if the average is correct.

* Remove sucker growth from the base of fruit trees and grape vines.

* Remove water sprout growth from fruit trees. Water sprouts grow straight up.

* "Comb" new growth on grape vines so these new shoots hang down for greater exposure to sunlight.

* Continue disease and insect control to prevent fruit damage. (Ward Upham)

There are about a dozen different species of soft scales collectively known as lecanium scale. But life histories are similar enough to treat them as a single entity for the purposes of this article. Normally, damage from lecanium scale is slight with "honeydew" raining down on anything under affected trees. Sooty mold, a fungus that feeds
on the honeydew, can turn branches and leaves black. Branch dieback is possible with large populations. Predators and parasites normally keep lecanium scale under control, but there are times when the population of beneficials is too low to provide immediate control. Unfortunately, later instars and adults are virtually impossible to control with insecticides. Only the crawler stage is susceptible, and the time of crawler emergence varies from year to year.

If you feel insecticides are necessary, target the crawler stage as it migrates from the dead mother's body to the leaves. This usually occurs about the time yucca plants flower. Trapping adults has shown that this week is a good time to apply treatments in Wichita as the crawlers are out. Apply a followup spray in another 10 days. More northern locations may want to wait until the yucca flowers. Registered products include permethrin (numerous trade names) cyfluthrin (Tempo, Bayer Vegetable and Garden Insect Spray), dinotefuran (Ortho Tree & Shrub Insect Control Ready To Use Granules), carbaryl (Sevin) and malathion. Though too late to apply now, imidacloprid (Bayer Tree and Shrub Insect Control, Bonide Systemic Granules IC) can be applied in the fall. (Ward Upham)

It is now time to “do battle” (I love military metaphors) with that “infamous” of insect pests known as the bagworm (Thyridopteryx ephemeraeformis). Throughout most of Kansas, bagworm eggs have hatched and the young caterpillars are out-and-about feeding on both broadleaf and evergreen trees and shrubs. Bagworms were first considered a pest of primarily conifers but over the years they have expanded their host range to include a number of broadleaf plants including rose, honeylocust, and flowering plum. I have even seen them “eating chicken wire” at the Sunset Zoo (Manhattan, KS).

At this time of year, what is the best way to deal with bagworm caterpillars and thus prevent them from causing damage? Handpicking any small caterpillars (along with their accompanying bag) and placing them into a container of soapy water will kill them directly. This is highly therapeutic and, if feasible, will quickly remove populations before they can cause substantial plant damage. You should consider having a weekend “bagworm handpicking party” with prizes awarded to those individuals that collect the most bags. For those less interested in the pleasures of handpicking, there are a number of insecticides labeled for use against bagworms including those with the following active ingredients (trade name in parentheses): acephate (Orthene), Bacillus thuringiensis subsp. kurstaki (Dipel/Thuricide), cyfluthrin (Tempo), lambda-cyhalothrin (Scimitar), trichlorfon (Dylox), indoxacarb (Provaunt), chlorantraniliprole (Acelepryn), and spinosad (Conserve). Many of these active ingredients are commercially available and sold under different trade names or generic products. However, several insecticides may not be directly available to homeowners. The key to dealing with bagworms when using insecticides is to make applications early and frequently enough in order to kill the highly susceptible young caterpillars that are feeding aggressively on plant foliage. Older caterpillars that develop later in the season, in the bags, may be 3/4-inches long, and are typically more difficult to kill with insecticides. In addition, females tend to feed less as they prepare for reproduction, which reduces their susceptibility to spray applications and any residues. The bacterium Bacillus thuringiensis subsp. kurstaki is active on young caterpillars; however, the active ingredient must be consumed to be effective, so thorough coverage of all plant parts and frequent applications are required to avoid having to deal with later stages. This compound is sensitive to ultra-violet light degradation and rainfall, which reduces any residual activity. Spinosad is the active ingredient in a number of homeowner products (including Borer, Bagworm, Tent Caterpillar & Leafminer Spray; Captain Jack’s DeadBug Brew; and Monterey Garden Insect Spray) and works by contact and ingestion (stomach poison); however, it is most effective when ingested and it can be used against older or larger bagworm caterpillars. Cyfluthrin, lambda-cyhalothrin, trichlorfon, chlorantraniliprole, and indoxacarb may be used against both the young and the older caterpillars. However, thorough coverage of all plant parts, especially the tops of trees and shrubs, where bagworms commonly start feeding, and frequent applications are required.

The reason why multiple applications will be needed when bagworms are first detected is because bagworms “blow in” (called ‘ballooning’) from neighboring plants. If left unchecked, bagworms can cause significant
damage, thus ruining the aesthetic quality of plants. In addition, they may actually kill plants, especially evergreens since they don’t usually produce another flush of growth, and newly transplanted small plants. If you have any questions regarding the management of bagworms, contact your county horticultural agent, or university-based or state extension entomologist. (Raymond Cloyd)

Contributors: Raymond Cloyd, Entomologist; Ward Upham, Extension Associate