Husker Hort

A Nebraska View of Horticulture


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Enjoy Roses: flowers, thorns, bugs and all

No doubts about it, roses were hit hard this winter. Whether you had hybrid tea roses or the tough-as-nails shrub roses, they all took a beating. Don’t let your roses suffer any more damage this summer, be on the lookout now and catch these common rose problems.

Japanese Beetles

Japanese Beetles

Japanese beetles are a common pest of roses. They will feed on most anything, but they have a love for roses. These insects are related to the May/June beetle and can be a major pest of roses. The immature form of the beetle is a grub that can do some damage to turfgrass. The adults hungrily devour roses and cause the most feeding damage. The front of this beetle is a dark metallic green and the wing covers are a dark tan or coppery color. The main identifying characteristics for these beetles are five small tufts of white hair along each side of the insect. They feed in clusters during the day on leaves or on the blooms. Adult Japanese beetles can cause the leaves to have a skeletonized appearance, ragged holes, or in some instances, the leaves are completely eaten.

Rose Chafers

Rose Chafers

Rose chafers are another beetle pest of roses. The adult beetles are slender, 1/2 inch long, and are light tan colored. They lack the tufts of hair that the Japanese beetles have. The long burnt-orange legs are the distinguishing characteristic that sets them apart, as they clumsily walk around. The adults feed on the foliage and flowers of roses, while the larvae feed on roots of grasses and alfalfa. Adults may feed together and can cause skeletonized leaves or ragged holes in the flowers.        

There are a few ways that you can control Japanese beetles and rose chafers on roses. If the infestation is light, hand picking is an option. Pick the beetles off in the early morning and drop them in a bucket of soapy water. There are also some deterrents that can be used like neem oil. Several insecticides are labeled for control of these pests with active ingredients like carbaryl, acephate, and chlorpyrifos. Keep in mind that these beetles are mobile and often new beetles take the place of those killed by insecticides. Try to avoid applying the products to the flowers or during times when bees are present because they can harm honeybees.

Black Spot on Roses- photo courtesy IANR Pubs http://www.ianrpubs.unl.edu/pages/publicationD.jsp?publicationId=674

Black Spot on Roses- photo courtesy IANR Pubs http://www.ianrpubs.unl.edu/pages/publicationD.jsp?publicationId=674

Some disease names lack imagination. Black spot of roses is one of those. This fungal disease causes the rose leaves to turn yellow then develop black spots, hence the name black spot of roses. The leaves that are affected might fall off, which can affect the appearance of the shrub. It can also reduce plant vigor, cause stunted growth, and increase the chance of winter kill. The fungal spores overwinter on fallen leaves and diseased canes. Rain splash or sprinkler impact easily spreads the spores onto healthy new plant material.    

Prevention is the best method for dealing with black spot. Following good sanitation practices like cleaning up rose beds in the fall will make sure to get rid of any old plant debris that could overwinter spores. Replacing old mulch with new, if black spot was a problem in the past in that location, as well as looking for and selecting rose varieties that are resistant to black spot will help to reduce or eliminate the need for a spray program.

Fungicides are another option for black spot control. For best results, most fungicide applications should be applied preventatively to healthy foliage to keep the leaves from becoming infected. Throughout the growing season, infected leaves should be removed as soon as symptoms begin to appear. On plants with a history of black spot, fungicides can begin to be applied as soon as the foliage begins to emerge in the spring and continued throughout the summer. Read and follow label instructions for application and reapplication recommendations. For best results, a fungicide should be used in combination with good cultural and sanitation practices.

With a keen eye, you can catch these issues before they become a pest in your rose bed.

For more information contact Elizabeth Killinger at elizabeth.killinger@unl.edu, 308-385-5088, on Facebook, Twitter, her blog at https://huskerhort.wordpress.com/, or visit the University of Nebraska-Lincoln Extension website: hall.unl.edu.

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Is that a Webworm or a Bagworm?

Webworms, bagworms, are they the same thing? If not, why does it make a difference whether you have a bagworm or webworms? It can make a big difference which insect you have to control and the damage that they cause. Correct identification is key to know how to control these pests.

Fall webworms or tent caterpillars are an occasional pest. They are sometimes called ‘bagworms,’ but using the correct common name will help clear up confusion. They appear as white webbed nests on the ends of branches in cottonwood, crabapple, walnut, and other trees. The caterpillars hide in the webbed nest during the day and feed on the trees at night. The caterpillars cause little harm to otherwise healthy trees. Tree health is not usually affected until more than 50 percent of the foliage is eaten. If there are enough nests, about one on every branch, the tree could be completely eaten. If you can safely reach the nest, use a broom to break up the bag of webworms. Follow up by spraying with a strong stream of water or an insecticide like permethrin (Eight) or Spinosad (Conserve). The nests can also be pruned out when possible. Trees that have heavy infestations this year won’t necessarily have a similar outbreak next year.

Bagworms on a juniper.

 

Bagworms are a whole different story from webworms. Bagworms will feed on a wide variety of trees and shrubs, but they mainly prefer evergreens, especially junipers, cedars, and spruce. The reason that they are called bagworms is because they spin their own individual cases or bags around them for protection. As the bagworm grows, so does the bag that contains them. They will add leaf fragments to the outside of the bag for camouflage. The bags look like baseball bat-shaped ornaments hanging from the trees. There is one way to know if your cedar tree has bagworms. If you see little cone shaped things on your cedar tree, more than likely you have bagworms, because cedar trees don’t produce cones.

The earliest sign of bagworm injury on junipers is brown stressed needles at the tips of the branches. If the infestation is severe enough, the tree they are feeding on will have a brown tint to it. Heavy infestations of older bagworms are capable of completely defoliating a tree or shrub. This can cause stress to the plant or even kill it if damage is great enough. This is especially true if they have infested an evergreen which is unable to re-grow new foliage until next year. If you have bagworms on any deciduous plant, ones that lose their leaves every year, they are able to re-grow foliage if needed. Just be sure to pick up the leaves this fall and dispose of them.

There are several options for controlling bagworms. Insecticidal sprays require thorough coverage to penetrate the canopy and contact the feeding bagworms. It is generally preferable to use ground equipment with higher spray volumes and pressures. Aerial applications may fail to provide thorough enough coverage resulting in less than satisfactory bagworm control. The spray has to completely cover the plant, almost to the point the product is dripping off of it. If the bagworms have made their home on a windbreak, the applicator has to be sure to have enough pressure to get product between the two rows of the windbreak. If this area is missed the bagworms that were hiding out there will move and re-infest the rest of the plant. Hand removal is another option for controlling bagworms. After removing the bags, place them in a bucket of soapy water.

There are several options available for insecticidal control of bagworms. Some of the reduced-risk options include Bacillus thuringiensis (Bt), spinosad, or azadirachtin (neem oil) are effective on young larvae and may be needed to be applied repeatedly. Additional insecticidal options include permethrin (Eight), bifenthrin (Talstar), cyfluthrin (Tempo), chlorantraniliprole, carbaryl (Sevin), dimethoate, esfenvalerate, fluvalinate (Mavrik), lambda-cyhalothrin, acephate (Isotox IV), and tebufenozide (Confirm). Depending on the product and size of the insect, secondary applications may be needed.

Be on the lookout now for webworms and bagworms and control them before they make a meal out of your plants.

For more information contact Elizabeth Killinger at elizabeth.killinger@unl.edu, 308-385-5088, on Facebook, Twitter, her blog at https://huskerhort.wordpress.com/, or visit the University of Nebraska-Lincoln Extension website: hall.unl.edu.


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Ants or Termites?

Spring is officially here. Trees are blooming, grass is greening up, and the insects are beginning to swarm. Ants will begin swarming…or wait are they termites? Knowing the difference between these insects can make a difference in whether you let them be or if you should be concerned.

Positive identification of the pest is crucial in knowing if control measures need to be taken. Both ants and termites can swarm outdoors in the spring; don’t automatically think when you see a swarm of insects that you have termites on your hands. There are a few distinguishing characteristics to help you quickly identify a swarm of ants from a swarm of termites. Ants have two pairs of wings. The front wing is slightly longer than the rear wing. When you look closely at the antenna, they will have ‘elbows’. Another characteristic to look for is the waist. Ants have a pinched waist between their second and third body segments. . Swarming ants can have wings to help them move the colony from place to place. Once they get to a location that they find suitable, they clip their wings off and look like ‘normal’ ants again.

Termites have a slightly different appearance. Termites also have two sets of wings, but both wings in the set are the same length and of equal size. The antenna of the termite is also slightly different than that of an ant. The antenna of a termite is straight, as opposed to elbowed like that of an ant. The waist of the termite is also different. Termites have a broad waist between their second and third body segments.

After properly identifying the pest, you can then select the control method. There are about a dozen ant species associated with homes in Nebraska. In the spring, ants often find their way into homes before food is available outdoors. Once an ant finds a suitable food source, it alerts all of its friends. It might make you feel good to kill the one scout ant, but there will be others. To get a good control of the ant population, you have to control the colony. There are three methods that you can use to control the colony. You can find the colony yourself and treat it. This approach may not be as easy as it sounds, especially if the colony is in the wall or under a concrete slab. Baits are another approach to treating for ants. Most of the ready-to-use baits work well on the sweet-loving ants, but some prefer protein. If the sweet-baits aren’t being eaten or don’t seem to be working, try a protein based bait. The last approach is to contact a licensed pest control company. They are able to apply a perimeter spray to help control the ants.

Termite control is a different story. A swarm of termites on the ground near the house doesn’t automatically mean you have a termite infestation, but it doesn’t hurt to have the home checked by a professional. The products that are on the market for termites should be applied by a licensed pest control operator.

I am sure you never thought you would have to look at the waist of an insect for proper identification, but you will be glad you did in the long run.

For more information contact Elizabeth Killinger at elizabeth.killinger@unl.edu, 308-385-5088, on Facebook, Twitter, her blog at https://huskerhort.wordpress.com/, or visit the University of Nebraska-Lincoln Extension website: hall.unl.edu.


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Attack of the Killer Wasps

 

Cicada Killer Wasp

Cicada Killer Wasp

It sounds like a scene right out of an old horror movie.  Insects are taking over the world.  Hornets are so large they are big enough to carry people away and insects are taking over homes and businesses.  I have to admit I might be exaggerating a bit, but there are some insects that can be frightening to look at or in such large numbers it might feel as if they are trying to take over.  In reality they are just more buzz than sting.

Cicada killer wasps have a frightening name, but that is about all.  These wasps are by far the largest wasp species in Nebraska, up to two inches long.  Their black bodies have a yellow stripe color pattern that is similar to other wasps.  Cicada killers, like their name implies, hunt cicadas, sometimes known as locusts.  They listen for the cicadas to sing then attack and sting to paralyze them.  They carry the paralyzed cicadas to their underground burrows where the female cicada killer will lay her eggs on it.  When the eggs hatch, the wasp larvae feed on the cicada.

The nests of these insects are not always placed in the best location.  The cicada killers’ nests are in the ground, usually near sidewalks, driveways, retaining walls or other areas of exposed soil.  They can be identified by the half-inch wide entrance hole with fresh soil surrounding it.  If you get close to their nest, they will alert you.  These wasps are very docile and often will just fly around your or act like they are coming after you.  When a person walks by a cicada killer, the wasp may become disoriented.  It will circle around the person as a way to reestablish its position, they not attacking.  While they are a wasp, they rarely sting unless severely provoked.

While control is rarely needed, there are some things you can do to ease your mind.  Cultural methods can be used to detour these wasps from making their nests in particular locations.  Since they make their burrows in out of the way places, take steps to encourage dense lawns or place extra mulch around the flowerbeds and around shrubs to cover bare soils.  Insecticidal control can be used if the nests do become a problem.  Use an insecticide labeled for use on wasps and be sure to read and follow the label instruction.  Take caution when applying insecticides to wasp burrows.  Apply products in the cooler parts of the day, either early morning or later in the evening, when the insects will be in their burrow and not as aggressive.

They might not be taking over the world, but there is an insect that is invading homes right now.  The strawberry root weevil is a common home-invading insect that is black or dark brown and about 1/4 inch long.  They are often confused with a tick, but they have 6 legs instead of the 8 that ticks have.  The larvae feed on the roots of strawberries, evergreens, brambles, and grapes.  The adults, which are all female, emerge in summer and feed on the edges of foliage, giving a notched appearance.

The beginning in late July to early August the adult strawberry root weevils begin to migrate into homes.  Once inside the home, they don’t cause any damage and are just more of an annoyance than anything else.  They are attracted to moisture and will often be found in sinks, bathtubs, or other similar places.  Control inside the home is rarely required, in a few weeks the migration will be completed.  Once found inside they can be vacuumed or swept up.  While there are pesticides labeled for inside home use, they are rarely recommended.  To prevent entry into homes, now would be the time to apply a perimeter spray that contains bifenthrin, cypermethrin or cyfluthrin.

Insects might not be taking over the world, but there are times when larger than average wasps and armies of strawberry root weevils invading homes might make it feel as if they are.

For more information contact Elizabeth Killinger at elizabeth.killinger@unl.edu, 308-385-5088, on Facebook, Twitter, her blog at https://huskerhort.wordpress.com/, or visit the University of Nebraska-Lincoln Extension website: hall.unl.edu.


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Grubs

 

White Grubs

White Grubs

June 21st marked the start of the summer season.  Summer means a good time for cookouts, picnics, swimming, and grub control.  Not exactly what you had in mind for summer fun?  Knowing the pest and its habits can help keep you from spending all of your summer fun time dealing with grubs.

White grubs are the larvae of a group of beetles called scarab beetles.  There are many scarab beetles in Nebraska, but only a few can cause significant damage to turf.  The more common ones include the masked chafer, or annual grubs, and the May/June beetles, or three-year grubs.  White grubs look very similar.  They have C-shaped bodies that are cream or white colored, have reddish-brown heads, and three pairs of short legs right behind the head.

There are minor differences between the species, but they all have the same type of feeding patterns.  The grubs feed below the soil surface on the roots of all common turfgrass species.  They are capable of destroying the entire root system of the plant if infestations are heavy enough.  The first signs of grub damage include areas of pale, discolored, dying grass displaying signs of moisture stress.  The adult beetles of these grubs rarely cause much damage and are more of a nuisance than anything.

Damaged areas are small at first, but will grow rapidly as the grubs grow and enlarge their feeding area.  The affected areas may feel spongy and can be easily lifted from the soil surface or rolled like a carpet.  Another indicator that your lawn may have grubs is small areas that are dug up by animals like raccoons, skunks, or moles foraging for the insects.

A few grubs in your lawn doesn’t necessarily mean that an insecticidal control is needed.  There are threshold levels that warrant insecticidal control.  For masked chafers 8-10 grubs per square foot and 3-5 per square foot May/June beetles are the threshold levels.  If you have more insects than that, a curative treatment will be needed, usually around the first week of August.  If you have had a history of grubs in your lawn, a preventative insecticide application the third week of June through early-July will have the insecticide in place when the eggs begin to hatch.

Products for grub control have changed over time.  Before 1999 grub insecticides were used as curative treatments.  They were fast acting, had a short residual activity and needed to be applied within a narrow treatment window.  New types of insecticides are now available that offer the opportunity for preventative treatments.  These products are slower acting, but they have a much longer period of residual activity and are available for a much wider treatment window.

There are a wide range of products that can be used to treat grubs.  Chlorpyrifos (Dusban), carbaryl (Sevin), isazophos (Triumph), Chlorantraniliprole (Acelyprin), Imidacloprid (Merit), and Halofenozide (Mach 2) are just some examples of the products that will work well to control grubs.  Trichlorfon (Dylox) can be applied for curative control if white grubs exceed threshold levels later in the season.  Be sure to read and follow the label instructions.

Keep in mind that no registered insecticide is 100% effective.  On average they usually kill 75 to 90% of the grubs present in any given area. Re-applications may be necessary when grub populations get very high.  Scouting early and catching the problem before the numbers get too high will help allow you to have a worry free summer.

Can’t get enough horticulture information?  Listen on Fridays at 8:15 a.m. on KRGI 1430 am to hear ‘Everything Outdoors.’  It is a live call-in radio show in which Hall County Extension Educator Elizabeth Killinger gets you the answers to your horticulture questions.

 

For more information contact Elizabeth Killinger at elizabeth.killinger@unl.edu, 308-385-5088, on Facebook, Twitter, her blog at https://huskerhort.wordpress.com/, or visit the University of Nebraska-Lincoln Extension website: hall.unl.edu.