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Horticulture Newsletter 2015, No. 30

7/28/2015

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Video of the Week:
When to Harvest Eggplants

Upcoming Events:

field day
Kansas Turf & Ornamentals Field Day
Thursday, August 6, 2015
K-State Research & Extension Center, Olathe

The field day program is designed for all segments of the turf industry - lawn care, athletic fields, golf courses, and grounds maintenance.  Included on the program are research presentations, problem diagnosis, commercial exhibitors, and equipment displays.  There will be time to see current research, talk to the experts and get answers to your questions.

Pesticide recertification credits in 3A and 3B are available, as well as GCSAA education points.

For more information and to register, go to:  https://www.eventbrite.com/e/kansas-turf-ornamentals-field-day-tickets-16109376579

Vegetables:
Common Smut on Sweet Corn

smut on sweet corn
Smut (Ustilago maydis) is a fungal disease of corn that may infect leaves, stems, tassels or ears though infections on ears are the most obvious. Immature galls are white and spongy but become brown with dark powdery spores with maturity. Leaf galls remain small but those on the ears or stems can become rather large and will release large numbers of spores when they rupture. This disease is likely to be most severe on plants injured by hail, cultivation or insects and tends to be worse on soils that have had heavy applications of nitrogen fertilizer or manure. Also anything that slows growth such as hot, dry weather or cool, wet weather when the plants are young can result in more infections.

Immature smut galls are considered an edible delicacy known as cuitlacoche in Mexico. They are a high value crop for some growers in the northeast U.S. who sell them to Mexican restaurants. There is no chemical control for this disease. Crop rotation and a balanced fertilizer program can help minimize this disease. Remove and destroy galls from infected plants before they rupture.  (Ward Upham)

Blossom-End Rot

Blossom end rot
Though we normally see this condition most commonly on tomatoes as evidenced by a sunken, brown, leathery patch on the bottom of the fruit, we can also see it on summer squash. Not a disease, this condition is caused by a lack of calcium in the developing fruit. It is often assumed that this means there is a corresponding lack of calcium in the soil. This is not necessarily the case, especially in Kansas. Most Kansas soils have sufficient levels of calcium. So what causes blossom-end rot? Actually, there are a number of possible causes. Let's look at some of them.

- This year, inconsistent amounts of water may be a factor. This can be due to watering practices or may be due to heavy rains followed by dry periods. Try to keep soil moist but not waterlogged. Mulching can help by moderating moisture levels over time.

- Vegetable tops will sometimes outgrow the root system during cooler spring weather. This is especially true of tomatoes. As long as it is cool, the root system can keep up. When it turns hot and dry, the plant has a problem, and water —with the calcium it carries — goes to the leaves and the fruit is bypassed. The plant responds with new root growth and the condition corrects itself after a couple of weeks.

- Heavy fertilization, especially with ammonium forms of nitrogen, can encourage this condition.  Heavy fertilization encourages more top than root growth and the ammonium form of nitrogen competes with calcium for uptake.

- Anything that disturbs roots such as hoeing too deeply can encourage blossom-end rot.  Mulching helps because it keeps the soil surface cooler and therefore a better environment for root growth.

There are some years you do everything right and the condition still shows up due to the weather. In such cases, remember that blossom-end rot is a temporary condition, and plants should come out of it in a couple of weeks. You may want to pick off affected fruit to encourage new fruit formation.

Soils with adequate calcium will not benefit from adding additional calcium. If your soil is deficient in this nutrient, add 1 pound gypsum per 100 square feet. Gypsum is calcium sulfate and will not affect pH. Though calcium raises pH, sulfate lowers it and the two cancel each other out. Even if not needed, gypsum will not hurt anything.

We have also found that spraying plants with calcium doesn't work. The fruit's waxy surface doesn't allow absorption of the material and calcium does not move from the leaves to the fruit.  (Ward Upham)

How to Pick a Ripe Melon

Picture
Telling when a melon is ready to be harvested can be a challenge, or it may be quite easy. It all depends on the type of melon.

Let’s start with the easy one. Muskmelons are one of those crops that tell you when they are ready to be picked. This can help you not only harvest melons at the correct time but also choose good melons when shopping.

As a melon ripens, a layer of cells around the stem softens so the melon detaches easily from the vine. This is called “slipping” and will leave a dish-shaped scar at the point of stem attachment. When harvesting melons, put a little pressure where the vine attaches to the fruit. If ripe, it will release or “slip.”

When choosing a melon from those that have already been harvested, look for a clean, dish-shaped scar. Also, ripe melons have a pleasant, musky aroma if the melons are at room temperature (not refrigerated).

Watermelons can be more difficult and growers often use several techniques to tell when to harvest.

1. Look for the tendril that attaches at the same point as the melon to dry and turn brown. On some varieties this will need to be completely dried before the watermelon is ripe. On others it will only need to be in the process of turning brown.

2. The surface of a ripening melon develops a surface roughness (sometimes called “sugar bumps”) near the base of the fruit.   

3. Ripe watermelons normally develop a yellow color on the “ground spot” when ripe. This is the area of the melon that contacts the ground.

Honeydew melons are the most difficult to tell when they are ripe because they do not “slip” like muskmelons. Actually, there is one variety that does slip called Earlidew, but it is the exception to the rule. Ripe honeydew melons become soft on the flower end of the fruit. The “flower end” is the end opposite where the stem attaches. Also, honeydews should change to a light or yellowish color when ripe, but this varies with variety. (Ward Upham)

Flowers:
Peony "Measles"

red spots on peony leaf
The weather this summer has resulted in many peonies catching the "measles." This is a disease, also known as red spot, that causes distinct, reddish-purple spots on the upper leaf surfaces.  These spots often coalesce and become large, reddish purple blotches on the upper leaf surfaces but are a light brown color when viewed from the underside of the leaves. The spots on stems will merge and form streaks that are reddish brown.

Sanitation is the best control for this disease.  Remove all diseased tissue, including stems, at the end of the growing season. Mulch that contains plant debris should also be discarded and then replaced with fresh mulch. Reducing the source of the inoculum will reduce the chances of another severe outbreak next year. (Ward Upham)

Pests:
Grasshoppers

Picture
We have received a number of calls on grasshoppers recently. Permethrin (numerous trade names) is a good choice for vegetable crops because it is labeled for a wide variety of vegetables. However, keep in mind that hoppers can reinfest an area relatively quickly. Many times gardeners have not had an insecticide failure, but a reinfestation. Carbaryl (Sevin) can also be used for grasshopper control but can lead to mite outbreaks as it is very toxic to mite predators.

We often have gardeners who are interested in organic controls. Nosema locustae, a protozoan, is the active ingredient in a number of products including Semaspore, NOLO Bait, HopperStopper and Grasshopper Attack. These products are selective and will affect only grasshoppers. This is a trait many gardeners find attractive. However, Nosema locustae products may not be as effective in garden situations as they would be under large-scale rangeland conditions due to potential reinfestations from outside the treated area. Also, these products have other potential disadvantages:- They are most effective against nymphal rather than adult grasshoppers. Also some grasshopper species are less susceptible than others.

- Kill can take 3 to 6 weeks after ingestion.

- These baits are perishable and should be kept refrigerated until use. Pay attention to the expiration date.

As mentioned above, reinfestations of uninfected grasshoppers can occur. These products are not effective against adults. Try to treat the nesting area when hoppers are small and populations are concentrated. Nosema locustae products are allowed in certified organic crop production.  Poultry including turkeys, guinea hens and chickens have also been used to help control grasshoppers.

Regardless of method used, the trick is to treat early before the population has matured. Young nymphal stages are much easier to control than adults and are also much less mobile. (Ward Upham)

Ornamentals:
Twig Dieback on Oak

twig dieback on oak
Recently we have seen twig dieback on pin and other oaks caused by a fungal disease called Botryosphaeria canker. Affected trees show wilting or “flagging” of terminal growth on the ends of branches. Dieback usually extends 4 to 6 inches down the twig with leaves bending back toward the twig before turning brown. Dead leaves remain attached to the tree. If you look closely at the twig, you should see a rather marked transition from healthy to diseased tissue. Take a knife and scrape away some of the outer bark tissue. Healthy tissue is light green. Diseased tissue tends to be brown to black.

Botryosphaeria canker differs from oak wilt in that only the tips of branches are affected. Oak wilt affects whole branches. This disease causes such minor damage that chemical control measures are unwarranted. Dead twigs on small trees may be pruned off if desired. (Ward Upham)

Contributors: Ward Upham, Extension Associate

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K-State Horticulture Newsletter 2015, No. 29

7/21/2015

2 Comments

 

Video of the Week:
Spider Mites

Ornamentals:
Tubakia Leaf Spot of Oak

Tubakia on red oak
This leaf spot disease of oak is showing up earlier and is more severe this year than normal.  Members of the red oak group are more likely to be affected than those in the white oak group, but members of both groups are showing symptoms now. Red oaks often have distinct round spots as well as dead areas that follow the veins. White oaks also have the dead areas that follow the veins and large blotches of dead tissue but lack the distinct spots.  Leaves severely damaged may drop.  However, trees rarely lose enough leaves to harm the health of the tree.  No fungicide sprays are recommended. (Ward Upham)

Squirrel Damage to Trees

squirrel damaged tree
Tree squirrels can cause a couple types of tree damage. Most commonly they clip the tips of branches. The length of severed branches is often 2 to 3 feet though they can be longer or shorter. When squirrels snip off a branch, they cut it at about a 45-degree angle and the cut is rather tattered. This is a nuisance type of damage and normally does not hurt the health of the tree.

More serious damage is caused when squirrels strip the bark off of limbs or rarely, the trunk.  Wounds can be quite large and the squirrel can effectively girdle the branch by removing all the bark completely around the circumference. Branches girdled in this way will die and the tree may be ruined if those branches are major.

Why squirrels do this is still a bit of a mystery. Some people think it is simply a means to sharpen their teeth or that they are seeking nesting material or water. Other people think that there are certain squirrels that are high-strung and cause this damage out of nervous energy.

If the damage is limited to snipping the ends off of branches, it is probably best to ignore the activity as the tree suffers little harm. But if real damage is occurring due to extensive bark removal, try feeding and watering them. If that doesn’t work, control may be necessary. Fox and gray squirrels are game animals and can be hunted in season where it is legal and safe to do so.  They can also be trapped and moved away from the area they are causing damage. For more information on control, see http://www.bookstore.ksre.ksu.edu/pubs/L863.pdf .  (Ward Upham)

Pests:
Cicada Killer Wasps

Cicada killer wasp
These large (1-1/3- to 1-5/8-inch long) wasps fly slowly above the ground. Cicada killers have a black body with yellow marks across the thorax and abdomen. Wings are reddish-orange. Although these wasps are huge, they usually ignore people. Males may act aggressively if they are threatened, but are unable to sting. Females can sting, but are so passive that they rarely do. Even if they do sting, the pain is less than that of smaller wasps such as the yellow jacket or paper wasp and is similar to the sting of a sweat bee.

The cicada killer is a solitary wasp rather than a social wasp like the yellow jacket. The female nests in burrows in the ground. These burrows are quarter-size in diameter and can go 6 inches straight down and another 6 inches horizontally. Adults normally live 60 to 75 days from mid-July to mid-September and feed on flower nectar and sap. The adult female seeks cicadas on the trunks and lower limbs of trees. She stings her prey, flips it over, straddles it and carries it to her burrow. If she has a tree to climb, she will climb the tree so the can get airborne and fly with cicada back to the nest. If not, she will drag it. She will lay one egg per cicada if the egg is left unfertilized. Unfertilized eggs develop into males only. Fertilized eggs develop into females and are given at least two cicadas. Cicadas are then stuffed into the female’s burrow. Each burrow normally has three to four cells with one to two cicadas in each.  However, it is possible for one burrow to have 10 to 20 cells.

Eggs hatch in two to three days, and larvae begin feeding on paralyzed cicadas.  Feeding continues for four to 10 days until only the outer shell of the cicada remains. The larva overwinters inside a silken case. Pupation occurs in the spring. There is one generation per year.

Cicada killers are not dangerous, but they can be a nuisance. If you believe control is necessary, treat the burrows after dark to ensure the female wasps are in their nests. The males normally roost on plants near burrow sites. They can be captured with an insect net or knocked out of the air with a tennis racket during the day. Carbaryl (Sevin) or permethrin may be used for control.

If you would like more detailed information on cicada killers, see Bob Bauernfeind’s article in the July 10, 2015 Kansas Insect Newsletter at http://entomology.k-state.edu/doc/Newsletters/2015/KSInsectNewsletter12.pdf  (Ward Upham)

Look for Bagworms Now

bagworm
Most calls on how to control bagworms come in late July to early August when damage appears. Bagworms are difficult to control when they are that large. They are much easier to kill while small. Bagworms overwinter as eggs inside the dead female’s bag. Young larvae normally hatch and emerge during mid to late May in Kansas. Now would be a good time to use control measures if you haven’t already sprayed.  However, make sure the bagworms are present by looking for a miniature version of the mature bagworm.  Also, check to be sure the bagworms are alive before spraying. Predators and parasites  can sometimes naturally control this pest.

Insecticides commonly used for controlling bagworms include acephate (Orthene), permethrin (numerous trade names), cyfluthrin (Bayer Vegetable and Garden Insect spray), bifenthrin (Bug Blaster II, Bug-B-Gon Max Lawn and Garden Insect Killer), lambda-cyhalothrin (Spectracide Triazicide, Bonide Caterpillar Killer) and spinosad (Conserve; Borer, Bagworm, Leafminer and Tent Caterpillar Spray; and Captain Jack's Dead Bug Brew). Spinosad is an organic control that is very effective on this pest.  Thorough spray coverage of foliage is essential for good control with any of these products. (Ward Upham)

Blister Beetles

Blister beetle
These beetles are notorious for quickly stripping vegetables (especially tomatoes) and ornamentals of their foliage. There are several species of blister beetles which vary in size (often between 0.5-0.75 inch long) and color (such as black, gray or brown-striped), but most are recognized by their elongated, narrow, cylindrical, soft bodies with middle body part (thorax) narrower than the head or wingcovers.

Some home gardeners like to use hand picking as a nonchemical method for controlling these large insects. However, wear gloves and use caution because these beetles contain a substance called cantharidin. This chemical is an irritant capable of blistering internal and external body tissues exposed to the chemical. On tender human skin, body fluids of adult blister beetles may cause large, erect, watery blisters.

Chemical control of blister beetles is also possible. Cyfluthrin (Bayer Vegetable and Garden Insect Spray) and gamma- or lambda-cyhalothrin (Spectracide Triazicide, Bonide Beetle Killer, Bonide Caterpillar Killer) can be used for control. Cyfluthrin has a 0 day waiting period and lambda-cyhalothrin has a 5-day waiting period on tomatoes. (Ward Upham)

Squash Vine Borer

squash vine borer
If you have squash or related plants that suddenly wilt and die, you may have squash vine borer. This insect will bore into the stems of squash, zucchini, pumpkins and gourds. Hubbard squash are a favorite, and butternuts are less likely to be attacked than other squash. Cucumbers and melons are usually not a target, although both can be affected by a disease that causes similar symptoms, known as bacterial wilt.

The adult of this insect is a clear-winged moth that resembles a wasp. The forewings are a dark metallic green but the rear wings are clear. The abdomen is orange with black spots. The larva is cream-colored and rather wrinkled. Adults emerge in the spring and lay eggs on or near susceptible plants. Larva bore into the plant and feed for about a month as they move toward the base. Mature larva will exit the plant, burrow into the soil and pupate where they remain until the next year. Each plant can have numerous borers. If you suspect squash vine borer, split the stem of a collapsed plant near where it enters the ground. Infested plants will be hollowed out and mushy and may contain borers. Unfortunately, there isn't much you can do at this late stage. Control measures should center on prevention.

Suggested preventative controls would include crushing the dull red eggs before they hatch, excavating larvae from stems before they cause much damage or using insecticide applications. Applications should begin when the vines begin to run (too late for that) and reapplied every seven to 10 days for three to five weeks. Direct the spray at the crown of the plant and the base of runners. Chemicals used for borer control in gardens are permethrin (Bug-No-More Yard & Garden Insect Spray; Eight Vegetable, Fruit & Flower Concentrate; Lawn, Garden, Pet and Livestock Insect Control; Lawn & Garden Insect Killer), bifenthrin (Hi-Yield Bug Blaster II, Bug-B-Gon Max Garden Insect Killer) or carbaryl (Sevin), applied as sprays or dusts. Continue on a 7 to 10 day reapplication schedule for 3 to 5 weeks. If plants wilt, look for the presence of holes and ooze. However, in extreme heat, these plants will wilt in the afternoon even if undamaged by this insect. (Ward Upham)

Miscellaneous:
Watering May Be Needed This Summer

slowly watering a tree
Many areas of Kansas went through an extremely wet spring.  Gardeners may assume that little watering may be needed this summer as the soils were completely recharged.  However, many will likely need to do more watering than they expect. 

Rain saturated soils can damage root systems.  Excess water drives oxygen out of the soil as pore spaces are filled with water. Every living cell in a plant must have oxygen to live. If there is no oxygen, roots will die. Therefore, many of our plants may need to be babied through the summer.

Newly planted trees are especially vulnerable as they have not established the extensive root system needed to absorb enough water during hot, dry, windy summers. Even trees two or three years old should receive special care even if the root system was not damaged by saturated soils. 

Deep, infrequent watering and mulching can help trees become established. Newly transplanted trees need at least 10 gallons of water per week, and on sandy soils they will need that much applied twice a week. The secret is getting that water to soak deeply into the soil, so it evaporates more slowly and is available to the tree’s roots longer. One way to do this is to drill a small hole (1/8") in the side and near the bottom of a 5-gallon bucket and fill it with water. Let the water dribble out slowly next to the tree. Refill the bucket once, and you have applied 10 gallons. Very large transplanted trees and trees that were transplanted two to three years ago will require more water.

A perforated soaker hose is a great way to water larger trees, a newly established bed or a foundation planting.  See the accompanying article for an inexpensive way to water trees.

In sunbaked soil, you may need to rough up the surface with a hoe or tiller to get water to infiltrate easily. It may be helpful to set the kitchen oven timer, so you remember to move the hose or shut off the faucet. If you are seeing surface runoff, reduce the flow. 

Regardless of method used, soil should be wet at least 12 inches deep. Use a metal rod, wooden dowel, electric fence post or something similar to check depth. Dry soil is much harder to push through than wet. Record the time that was required to reach 12 inches and then use a time clock for any future waterings.  (Ward Upham)

Inexpensive Method of Watering Trees

Y-Adapter to attach to soaker hose
We mentioned in an accompanying article about using a soaker hose to water trees.  We thought it might be helpful to provide more details. 

Soaker hoses are notorious for non-uniform watering. In other words, you often receive too much water from one part of the hose and not enough from another.  Hooking both the beginning and the end of the soaker hose to a Y-adapter helps equalize the pressure and therefore provide a more uniform watering.  The specific parts you need are shown in the photo above and include the soaker hose, Y-adapter and female to female connector.

It is also helpful if the Y-adapter has shut off valves so the volume of flow can be controlled.  Too high a flow rate can allow water to run off rather than soak in.  

On larger trees, the soaker hose can circle the trunk at a distance within the dripline of the tree but at least ½ the distance to the dripline. The dripline of the tree is outermost reach of the branches. On smaller trees, you may circle the tree several times so that only soil which has tree roots will be watered.  (Ward Upham)

Contributors: Ward Upham, Extension Associate

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Horticulture Newsletter 2015, No. 28

7/14/2015

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Video of the Week:
Dividing Iris

Flowers:
Dividing Iris

iris rhizome
Bearded irises are well adapted to Kansas and multiply quickly. After several years, the centers of the clumps tend to lose vigor, and flowering occurs toward the outside. Dividing iris every three to five years will help rejuvenate them and increase flowering.

Iris may be divided from late July through August, but late July through early August is ideal.  Because iris clumps are fairly shallow, it is easy to dig up the entire clump. The root system of the plant consists of thick rhizomes and smaller feeder roots. Use a sharp knife to cut the rhizomes apart so each division consists of a fan of leaves and a section of rhizome. The best divisions are made from a double fan that consists of two small rhizomes attached to a larger one, which forms a Y-shaped division. Each of these small rhizomes has a fan of leaves. The rhizomes that do not split produce single fans. The double fans are preferred because they produce more flowers the first year after planting. Single fans take a year to build up strength.

Rhizomes that show signs of damage due to iris borers or soft rot may be discarded, but you may want to physically remove borers from rhizomes and replant if the damage is not severe. It is possible to treat mild cases of soft rot by scraping out the affected tissue, allowing it to dry in the sun and dipping it in a 10 percent solution of household bleach. Make the bleach solution by mixing one-part bleach with nine parts water. Rinse the treated rhizomes with water and allow them to dry before replanting.

Cut the leaves back by two-thirds before replanting. Prepare the soil by removing weeds and fertilizing. Fertilize according to soil test recommendations or by applying a complete fertilizer, such as a 10-10-10, at the rate of 1 pound per 100 square feet. Mix the fertilizer into the soil to a depth of 6 inches. Be wary of using a complete fertilizer in areas that have been fertilized heavily in the past. A growing number of soil tests show phosphorus levels that are quite high. In such cases, use a fertilizer that has a much higher first number (nitrogen) than second (phosphorus). (Ward Upham)

Ornamentals:
To Ditch Dig or Not Ditch Dig?

old seed packets
Well, that is a question, but probably not the question most of you are thinking about. You may have considered stopping to dig up a plant that caught your eye on the side of the road at one time or another. I, myself, may or may not have participated in one such (ahem)…activity at some point in my life. But is it wise? Well, let’s talk about that for a minute.

First of all, moving a plant from its native place at the height of its season of interest is most often a fatal move. If the season of interest is anytime other than winter (when plants are dormant) then it is likely when the plant is actively growing. You probably notice plants on the side of the road most often when they are in bloom, which takes a great amount of energy (it is reproductive activity, after all). If the plant is actively growing and flowering, then it needs access to as many resources as it can get—all of the roots to gather water, nutrients and leaves to photosynthesize and make food.  Cutting off one of those resources (primarily roots when you dig it up) puts the plant under great stress. It needs a lot of water. If you plant it immediately, it MIGHT survive. It is unlikely to thrive right away if it does survive. More often, the process will kill the plant and your efforts will have been for naught. How disappointing.

There’s a bigger problem with ditch digging that has nothing to do with plant survival. Quite the opposite actually. Ever heard of kudzu, “The Plant That Ate the South?” Kudzu is a climbing vine that traverses anything in its path, including other trees and shrubs, which it shades out and kills. It was first introduced to the U.S. as an ornamental shrub, “an effortless and efficient shade producer” in 1876. Later (in the 30s and 40s), it was rebranded as a remedy for soil erosion and farmers were paid $8 an hour to sow it into more than one million acres of topsoil. Oh my.

Not all invasive species are introduced like kudzu was, but most are as challenging to get rid of as kudzu continues to be. What are invasive plants? These are nonnative, introduced species which have a tendency to spread and are believed to cause damage to the environment, the economy and/or human health. Please note the entire definition —tendency to spread and cause damage. We have a great many introduced ornamental plant species that grow and perform exceptionally well in our climate without also becoming invasive. Indeed, if it were not for plant hunters exploring the world, we would not have nearly the amount of diversity in our landscapes as we do today. Nor is a native-only landscape the only way to garden. It is a way to garden. Introduced species are not necessarily evil. But I digress, perhaps that is a discussion for another article.

The key here is to know what is considered invasive in our part of the world. This information can generally be found by searching for your state name and “invasive species.” The USDA manages lists from a national level and there are often statewide “council” organizations that provide educational material for free. For instance, the Kansas Forest Service (www.kansasforests.org) and the Kansas Native Plant Society (www.kansasnativeplantsociety.org) publish lists of plants considered the worst invasive species in the state. A highlight from this list is Amur honeysuckle (Lonicera maackii), which is quite eye catching both the spring (yellow/white flowers) and in the fall with its abundant bright red berries. But don’t move it to your house.  Wisdom, environ-mental concern and the law should prevail in this situation. It is against federal and state laws to grow or move (intentionally or unintentionally) species considered invasive (www.invasivespeciesinfo.gov/laws/publiclaws.shtml). I can’t calculate the likelihood of “plant police” pursuing you, but now you know better and can do your part to preserve our native lands.

It’s worth noting that not every plant is invasive in every state. For example, butterflybush (Buddleja) is a beautiful, free-flowering woody perennial that is available in just about any size and color you desire. They are excellent choices in the Great Plains. However, in Oregon they are considered invasive and are illegal for nurseries to grow and sell. Traditional species, that is. Because of their free-flowering (and free-seeding), many breeders have worked to develop sterile cultivars (producing 2% or less of viable seed) that can be grown and sold in regions where butterflybush is considered invasive. We benefit from these innovations with new colors, sizes and growth habits. Recent introductions you might be familiar with include the dwarf varieties Low and Behold® ‘Blue Chip’, ‘Blue Chip Jr.’, ‘Ice Chip’, ‘Lilac Chip’ and ‘Pink Micro Chip’. There are also some delicious-sounding cultivars in the Fluttterby Grandé™ series: ‘Blubberry Cobbler Nectar Bush’, ‘Peach Cobbler Nectar Bush’, ‘Sweet Marmalade Nectar Bush’, ‘Tangerine Dream Nectar Bush’ and ‘Vanilla Nectar Bush’. Boy, those marketers sure do know how to make our mouths water for new plants. Since we’re not in Oregon, you don’t need to know the full list of approved butterflybush cultivars. However, the invasive plant discussion is a passionate and nuanced one, which involves many puzzle pieces. In the end, it’s most important to “Know Before You Grow.” And that, my friends, is all anyone can ask.  (Cheryl Boyer)

Pests:
Flatid Planthoppers

flatid planthopper
These small, hopping insects are causing concern among gardeners because they are so noticeable. What people often see first is not the insect but the filaments of white, wool-like wax they leave behind. Nymphs are also coated with this white, powdery wax but adults of the species I've observed (citrus planthopper?) are more of a grayish color with a darker rear end. Only the adults have wings that are held over the body like a pup tent. Nymphs are more flattened and may not appear to be insects at first because of the waxy coating.

Plant injury due to these insects is usually minor. Feeding by large populations may cause death of seedlings or wilting of small twigs of larger plants. Control is usually not recommended because natural enemies often keep flatid planthoppers in check. If control is warranted, a strong stream of water from a hose should knock them off or a number of insecticides may be used including malathion, permethrin, cyfluthrin, and bifenthrin. For a detailed description, check out the University of Georgia Bugwood page at http://wiki.bugwood.org/Archive:Ash/Flatid_Planthoppers   (Ward Upham)


Spider Mites on Tomatoes

spider mite damage on tomatoes
We have seen some impressive spider mite damage on tomatoes.  This is a little surprising considering how little hot and dry weather we have had this summer. 

Look for stippling on the upper surface of the leaves as well as some fine webbing on the underside of the leaves.  These tiny arthropods (they are not true insects) are often difficult to see due to their size and their habit of feeding on the underside of leaves.  If mites are suspected, hold a sheet of white paper beneath a leaf and tap the leaf. Mites will be dislodged and can be seen as tiny specks on the paper that move about.

Spider mite control can be challenging.  A strong jet of water can be used to remove the mites but may not be as easy as it sounds.  A high-pressure directed spray is needed to dislodge the mites.  Since spider mites feed on the underside of the leaves, the spray is most effective if it comes from below.  This can be difficult to accomplish with a thumb over the end of the hose. Some gardeners use a water wand hooked to a shut-off valve.  The water breaker is then replaced by a brass nozzle. 

Horticultural oils and insecticidal soaps (Safers, for example) can also be helpful.  Spray early in the morning when temperatures are cooler and plants have rehydrated.  Resprays will likely be needed.  (Ward Upham)

Squash Bug Control

squash bugs
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:


Picture
To see the complete study, go to http://entomology.osu.edu/welty/pdf/VegIPMReport2005.pdf  
(Ward Upham)

Fruit:
When to Pick Peaches

peach ripening
Peaches are best when ripened on the tree but fruit growers may wish to pick a bit early to prevent damage from birds, have a higher pectin content for jams and jellies or to have firmer fruit for canning.

Peaches that are mature enough to pick are still hard. They do not give when lightly squeezed.  However, these peaches will ripen off the tree and will have very good quality. They may not be quite as sweet as a tree-ripened peach but are still very good. So what do we look for to tell if a peach is mature enough to harvest? Let’s look at a couple of factors.

Color: The reddish coloration is not a good indicator. Look instead for what is called the “ground color.” This is the part of the peach that does not turn red; for example around the stem.  The ground color of the peach will lose its greenish tinge and turn yellow when the peach is mature enough to harvest. I use this characteristic more to determine when NOT to pick a peach.  If there is any green in the ground color, it is too early. If the ground color is yellow, then I move to the next characteristic.

Ease of Removal: A mature peach will separate easily from the branch if the peach is lifted and twisted. If it doesn’t, it is not mature enough to pick yet.

All peaches will not be ready to pick at the same time. Pick only those that are ready and come back later for more. It often takes 3 to 5 pickings to harvest a peach tree.

Peaches that are picked early but will be used for fresh eating should be allowed to ripen inside at room temperature. Once they are ripe, they can be refrigerated to preserve them for enjoyment over a longer period of time. (Ward Upham)

Miscellaneous:
Robin Ruether Awareded "Top 40 Under 40" Award

Robin Ruether has been awarded the “Top 40 under 40” award from Greenhouse Product News Magazine. Robin manages the Prairie Star and Prairie Bloom Trials for Kansas State University. See http://www.prairiestarflowers.com/  She also authors a blog on flower varieties tested by KSU (http://www.prairiestarflowersblog.com/blog ), serves as an All-America Selections judge and contributes to the National Plant Trials Database.  Congratulations to Robin on a job well-done!  Link to original article:  http://www.gpnmag.com/robin-ruether.  (Ward Upham)

Contributors: Cheryl Boyer, Nursery Crops Specialist; Ward Upham, Extension Associate
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Horticulture Newsletter 2015, No. 27

7/7/2015

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Video of the Week:
Mulch: Trees Need to Breathe

Turfgrass:
Bermudagrass Control

bermudagrass in tall fescue
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)

Fruit:
Prop Up Fruit Tree Limbs if Needed

fruit tree limbs propped up
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)

Tan or White Drupelets on Blackberry and Raspberry Fruit

blackberry with tan drupelets
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)

Vegetables:
Harvesting Potatoes

Picture
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)

Pests:
Japanese Beetles (JB)

Japanese Beetle
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)

Walnut Caterpillars

walnut caterpillars
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)

Spittlebugs on Eastern Redbuds

spittlebug
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)

Miscellaneous:
Herbicide Drift Damage

herbicide drift damage on oak tree
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

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    Authors

    Ward Upham runs the Horticulture Response Center in the Department of Horticulture and Natural Resources at Kansas State University. Other contributors include K-State Extension Specialists.

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