Montgomery County
400 Bridge Street, Suite 2
Red Oak, IA 51566-1402
712-623-2592
FAX 712-623-2594
E-mail: drey@iastate.edu
HORTICULTURE
NEWSLETTER
DATE: JULY 2011
Bill Drey
Bill Drey
Montgomery County Extension Education Director
JULY 26—MONTGOMERY COUNTY Extension Office
Summer Webinar series
6:30 p.m. to 8:30 p.m.
Tallgrass Prairies of Iowa is the topic of the third session this summer on July 26. During this
session, the history and reach of the Tallgrass Prairie Center located in Cedar Falls, Iowa, will be
displayed. The mission of the Tallgrass Prairie Center is to ‘develop research, techniques,
education and Source Identified seed for restoration and preservation of prairie vegetation…’.
Daryl Smith, from the Tallgrass Prairie Center and University of Northern Iowa, is the presenter.
Armstrong Demonstration Garden Field Day
Armstrong Research Farm
July 28, 2011
6:00 p.m.
This year’s Home Demonstration Garden Field Days are devoted to children and cats. One
feature is the numerous flowers and vegetables named after storybook characters — ideal for
kids who enjoy reading. Another section of the garden showcases summer squash with feline
friendly names like cougar, jaguar and leopard. The gardens also will feature a variety of
“bumpy” pumpkins, sunflowers and many new flowers and vegetables.
Yard and Garden: Sweet Corn
BY RICHARD JAURON
One of the pure pleasures of summertime in Iowa is eating sweet corn fresh from the garden or
farmers' market. Gardeners have questions when it comes to getting the ears from field to plate. ISU
Extension specialists offer answers to those questions; to have additional questions answered, contact
the experts by emailing or calling the ISU Extension horticulture hotline at hortline@iastate.edu or 515294-3108.
When should I harvest sweet corn?
Sweet corn should be harvested at the milk stage. At this stage, the silks are brown and dry at
the ear tip. When punctured with a thumbnail, the soft kernels produce a milky juice. Over-mature sweet
corn is tough and doughy. An immature ear will not be completely filled to the tip and the kernels produce
a clear, watery liquid when punctured.
The harvest date can be estimated by noting the date of silk emergence. The number of days
from silk emergence to harvest is approximately 18 to 23 days. Prime maturity, however, may be
reached in 15 days or less if day and night temperatures are exceptionally warm. Most hybrid sweet corn
varieties produce two ears per plant. The upper ear usually matures one or two days before the lower
ear.
Harvest sweet corn by grasping the ear at its base and then twisting downward. Use or
refrigerate sweet corn immediately after harvest. Optimum storage conditions for sweet corn are a
temperature of 32 F and a relative humidity of 95 percent.
The ears on my sweet corn are poorly filled. What are possible causes?
Poorly filled ears are often the result of poor pollination. Hot, dry winds and dry soil conditions
may adversely affect pollination and fertilization and result in poorly filled ears. Water sweet corn during
pollination if the soil is dry. Improper planting may also affect pollination. Corn is wind pollinated. Plant
sweet corn in blocks of four or more short rows to promote pollination.
How can I keep raccoons out of my sweet corn?
The most effective way to prevent damage to the sweet corn crop is to encircle the area with an
electric fence. A two-wire fence with one wire 4 to 6 inches above the ground and the other at 12 inches
should keep the raccoons out of the sweet corn. Mow or cut the vegetation beneath the fence to avoid
electrical shorts. To be effective, the electric fence should be installed about two weeks before the sweet
corn reaches the milk stage.
Are there special corn varieties that are grown to produce “baby” corn?
The small size of “baby” corn suggests that it’s a special variety. However, most baby corn is
actually grown from regular sweet and field corn varieties. The ears are harvested when they are 2 to 4
inches long and one-third to one-half inch in diameter at their base. Most corn varieties reach this stage
one to three days after the silks become visible. While many sweet and field corn varieties are suitable
for baby corn production, there are a few varieties, such as ‘Babycorn’ and ‘Bonus,’ which are grown
specifically for the miniature ears.
Yard and Garden: Vegetable Pests
BY RICHARD JAURON
When it gets warm in the garden, the garden pests — worms, bugs and beetles — begin to feed and become a
nuisance. Iowa State University Extension specialists offer a variety of ways to control some of the more common
garden pests. Vegetable gardeners with questions about the management of other pests may contact the experts by
emailing or calling the ISU Extension horticulture hotline at hortline@iastate.edu or 515-294-3108.
How can I control squash bugs?
Squash bugs can be serious pests of summer and winter squash. Squash bugs have piercing-sucking mouthparts.
Heavy feeding causes entire leaves to wilt, turn brown and die. Several methods can be used to control squash bugs in
the garden. Brick red egg masses on the undersides of leaves and squash bug adults can be removed by hand. Adults
can also be trapped under boards or shingles placed under the plants. Turn the objects over daily and collect and
destroy the hiding squash bugs. Small, immature squash bugs (nymphs) can be controlled with insecticides, such as
Sevin, permethrin or insecticidal soap. Sprays are generally more effective than dusts. If the squash plants are
blooming, spray in the evening after the honey bees have quit foraging for the day. In fall, remove and destroy garden
plant debris to deprive squash bugs of overwintering sites. (photo by Whitney Cranshaw, images.bugwood.org)
There are tiny holes in the foliage of my eggplants. What should I do?
The tiny holes are likely due to flea beetles. Flea beetles are the most common pest of eggplant in the home garden.
Adults are tiny, shiny, black beetles. They possess large hind legs that enable them to jump. Flea beetles eat small,
round holes in the eggplant foliage, resulting in “shothole” damage. Minor flea beetle damage will have little effect on
crop yields. If significant damage begins to appear, treat plants with an insecticide. As always, carefully read and follow
label directions when using pesticides.
How can I control Colorado potato beetles?
The Colorado potato beetle is difficult to control. Hand picking has been used since before the development of
modern pesticides. Hand-pick beetles, eggs and small larvae from infested plants as soon as possible (practical for a
few insects on a few plants, but impractical for larger gardens). It’s especially important to remove overwintering beetles
that appear on young plants in spring.
In large gardens, insecticides are often the best option. When insecticides are necessary, consider timing, coverage
and insecticide choice. Timing is critical. Small larvae are much easier to control and spraying when the larvae are small
is much more effective than spraying when the larvae are large. Early treatment is also necessary to prevent crop loss.
Complete and thorough coverage of infested plants is necessary for good control. Control is generally more effective
with liquid sprays than with dust applications. (photo by Whitney Cranshaw, images.bugwood.org)
Because of decades of repeated insecticide use, the Colorado potato beetle is resistant to many widely used garden
insecticides, such as Sevin. The first-choice products are the synthetic pyrethroids, such as permethrin, cyfluthrin and
esfenvalerate. Look for products labeled for use on potatoes in the home garden and apply according to label directions.
Spray early and spray often. Biorational pesticides, such as spinosad, Bt tenebrionis and Neem (azadirachtin) are only
effective on very young larvae.
How do I control cabbageworms?
Cabbageworms are greenish caterpillars that eat large, irregular holes in the foliage of cabbage, broccoli, cauliflower
and Brussel sprouts. Cabbageworms can be controlled with biological or chemical insecticides. Bacillus thuringiensis
(Bt) is a biological insecticide (a bacterium) that specifically targets caterpillars. Bt products include Dipel, Thuricide and
others. Home gardeners can also use chemical insecticides, such as permethrin (e.g. Eight) or carbaryl (e.g. Sevin).
There are large green caterpillars with horn-like projections on my tomato plants. What are they and how can they be
controlled?
The large green caterpillars are tomato hornworms. Tomato hornworms can be 4 to 5 inches long and nearly as big
around as your thumb.
Tomato hornworms feed on the leaves and fruit of tomatoes and other vegetables including eggplant, potatoes
and peppers. They can quickly defoliate portions of a plant, reduce its productivity and heavily damage the fruit.
In regards to control, one option is to pick them off by hand (they won’t hurt you). Another option is to use a
biological insecticide known as Bacillus thuringiensis (Bt) or a synthetic home garden insecticide available at garden
centers. Be sure to follow label directions.
Yard and Garden: Trees
BY RICHARD JAURON
Trees are one of the most valuable assets in a landscape. All properties enjoy the benefits of having healthy
and beautiful trees. In addition to the aesthetic appeal, a healthy tree can add value to a property. Home
gardeners with questions about the management of other tree diseases may contact the experts by emailing or
calling the ISU Extension horticulture hotline at hortline@iastate.edu or 515-294-3108.
My crabapple has begun to drop some of its leaves. Why?
The leaf drop is probably due to apple scab. Apple scab is a fungal disease caused by the fungus Venturia
inaequalis. Cool, wet weather in spring favors apple scab development. Crabapple varieties differ in their
susceptibility to apple scab. Some varieties are very susceptible to the disease, while others are resistant to apple
scab.
Apple scab appears as velvety, olive-green to black spots on the crabapple leaves. Heavily infected leaves
turn yellow and fall from the tree. Highly susceptible crabapple varieties may lose a large percentage of their
leaves by mid-summer. Fortunately, apple scab does not kill affected trees. The damage is mainly aesthetic.
Apple scab can be prevented by applying fungicides from bud break through mid-June. For most home
gardeners, however, controlling apple scab with fungicides is not practical. Sanitation also plays a role in
controlling apple scab. Raking and destroying the leaves as soon as they fall should help reduce the severity of
the infection next season. However, the best way to prevent apple scab is to plant scab-resistant crabapple
varieties.
Why are the leaves on my pin oak yellow-green?
In Iowa, the foliage of the pin oak (Quercus palustris) often turns a sickly yellow-green. The yellow-green
foliage is due to a deficiency of iron. The problem is referred to as iron chlorosis. (A close examination of chlorotic
leaves will show that while most of the leaf is yellow-green, the tissue around the major veins is a darker green.)
Most soils in Iowa contain sufficient amounts of iron. However, in alkaline soils (those with a pH above 7.0), the pin
oak is unable to absorb adequate amounts of iron because much of it is in an insoluble form. Since many soils in
Iowa are alkaline, chlorotic pin oaks are common in Iowa. Wet soil conditions make absorption of iron even more
difficult.
Correcting an iron chlorosis problem is difficult. Applying additional iron to the soil usually doesn’t help. The soil
already contains sufficient amounts of iron. Adding more iron doesn’t overcome the problem. Lowering the soil pH
to 6.0 to 6.5 would allow the roots of the pin oak to more readily absorb iron in the soil. Unfortunately, lowering the
soil pH is extremely difficult, if not impossible. As a result, homeowner efforts to treat iron chlorosis are often
unsuccessful.
One strategy that sometimes works is to have an arborist or other tree care professional inject an iron
containing compound directly into the trunks of chlorotic pin oak trees. The effects of a trunk injection may last
three or four years.
Why is my sycamore tree dropping its leaves?
The leaf drop is likely due to anthracnose. Anthracnose is a common fungal disease of sycamore, ash, maple,
oak and other trees. Anthracnose is most severe in years with cool, wet spring weather. While anthracnose may
cause extensive defoliation, it does not cause serious harm to healthy, well-established trees.
Symptoms of anthracnose on sycamores include brown blotches on the leaves, death of young buds and
shoots, and leaf drop. In cool, wet springs, affected sycamores may lose most of their initial foliage.
Fortunately, the sycamore trees will continue to produce additional leaves and shoots through early summer.
Foliage that develops in late spring and early summer shouldn’t become infected as warmer, drier weather
suppresses anthracnose. Most sycamores should have a good canopy of leaves by late June or early July.
Since anthracnose does not cause serious harm to sycamores, fungicide treatments are rarely warranted.
The leaves on my peach tree are puckered and reddish in color. What is the problem?
The symptoms are those of peach leaf curl. Peach leaf curl is a fungal disease. The disease is caused by the
fungusTaphrina deformans. Infections occur as the peach tree buds begin to swell in spring.
A single fungicide application will control peach leaf curl. Fungicides, such as lime sulfur, Bordeaux mixture or
chlorothalonil, should be applied in fall after leaf drop or in late March before the buds begin to swell. To achieve
control, all branches and twigs must be thoroughly sprayed.
Yard and Garden: Strawberries
By
RICHARD JAURON
The strawberry is the most popular small fruit grown in the home garden. It is relatively easy to grow, produces large quantities
of fruit high in vitamin C without requiring extra equipment and can be grown in home gardens all over Iowa. Gardeners with
questions about strawberries and other berries may contact the experts by emailing or calling the ISU Extension horticulture hotline
at hortline@iastate.edu or 515-294-3108.
When should strawberries be harvested?
Harvest strawberries when the fruit are uniformly red (fully ripe). Pick the berries with the caps and stems attached to retain
firmness and quality. Pinch off the stem about one-fourth inch above the cap. Don’t pull them off.
Strawberries should be picked about every other day in warm weather, every three to four days in cool weather. The harvest
period for some June-bearing varieties may last three to four weeks. Strawberries can be stored in the refrigerator for up to five to
seven days. Optimum storage conditions are a temperature of 32 F and a relative humidity of 90 to 95 percent.
Some of my strawberries are covered with a gray, velvety growth. What is it and how can it be controlled?
The gray, velvety growth on your berries may be gray mold. It also is known as Botrytis fruit rot. Gray mold is favored by poor air
circulation and a high humidity in the strawberry planting. The most commonly infected berries are those touching the soil or other
infected berries.
Cultural practices can reduce losses due to gray mold. Do not fertilize June-bearing strawberries in spring. The application
of a nitrogen-containing fertilizer in spring promotes lush, vegetative growth. Dense foliage slows the drying of the strawberry
planting, resulting in a more favorable environment for gray mold. Control weeds in the strawberry bed. Weeds reduce air circulation
and slow the drying of the strawberry plants. Mulch the planting with straw to keep the berries off the ground. Berries resting on a
damp or wet soil are more susceptible to gray mold. During dry weather, irrigate in the morning when using a sprinkler. Plants dry
quickly when irrigated in the morning.
“Clean-pick” the strawberry planting. Harvest frequently. Pick berries as soon as they are ripe. Handle berries carefully during
harvest to avoid bruising the fruit. Immediately refrigerate the unwashed berries. Berries that exhibit symptoms of gray mold should
be picked and removed from the bed. Finally, fungicides are used by commercial strawberry growers to control gray mold. However,
cultural practices are the best way to control Botrytis fruit rot in home gardens.
Why do my strawberries have a slightly bitter taste?
The flavor of most fruits and vegetables is influenced by weather conditions. In regards to strawberries, warm sunny weather
produces the most flavorful fruit. When the weather is extremely hot, the berries may have a slightly bitter taste. Strawberry plants
produce smaller quantities of sugars when the weather is cool and cloudy. As a result, berries are not as sweet when the weather is
cool and rainy in May and June.
Leather rot, caused by a fungal disease, can be a problem in wet weather. Infected fruit have a leathery texture and bitter taste.
My June-bearing strawberry patch was flooded in June. Can I harvest the berries?
Berry fruits, such as strawberries, are highly susceptible to bacterial contamination. Silt and other contaminants may become
imbedded in the fleshy fruit and are difficult to remove. Since the berries were present when the garden was flooded, do not harvest
and eat any of the fruit. Renovate the strawberry patch in early July. Next year’s crop should be safe to eat if additional flooding
doesn’t occur during fruit development.
How can I prevent birds from eating my strawberries?
Birds can destroy 20 to 30 percent of a strawberry crop. The best way to prevent crop loss in the home garden is to place
protective netting over the planting. Netting can be purchased at garden centers or through mail-order catalogs. Attach the netting to
a frame that sets over the strawberry planting. The netting should be kept several inches above the plants so birds can’t peck at the
fruit through the netting. The structure also should be designed so the netting can be easily removed to harvest the fruit.
There are small, black, yellow-spotted beetles feeding on my strawberries. What should I do?
The small, black beetles are likely sap beetles. They are also known as picnic beetles or picnic bugs. Sap beetles commonly
feed on overripe or damaged fruits and vegetables in the garden.
Sanitation is the best management strategy for sap beetles in home gardens. Keep the strawberry patch as clean as possible
through timely picking and removal of damaged, diseased and overripe fruit.
Insecticide sprays are available for sap beetles, but they are difficult to use because they are applied to a crop that is ready for
harvest or while harvest is under way. If you do spray, use an insecticide with a short harvest-waiting interval and follow label
directions carefully.
There are small masses of foam-like material on my strawberry plants. What are these foam-like masses?
The foam-like masses on the strawberry plants were probably created by the meadow spittlebug. The meadow spittlebug is one
of several species of this commonly recognized group of sap-feeding insects. Spittlebugs are familiar because of the frothy, wet
mass of "spittle" that surrounds the nymphs as they feed on sap from their host plants. The spittle is produced by the immature stage
of the insect (the nymph) and protects the nymphs from natural enemies and desiccation.
While the foam-like masses of spittlebugs are conspicuous and somewhat obnoxious, spittlebugs cause little harm to plants.
Control efforts usually are not warranted.
Yard and Garden: Iris
| BY RICHARD JAURON,
Bearded iris is a beautiful spring flower, available in nearly every color. Each flower is made up of three upright petals
(standards) and three drooping petals (falls). Each fall has a fuzzy, beard-like growth at its base. Gardeners with questions
about irises and other garden plants may contact the experts by emailing or calling the ISU Extension horticulture hotline at
hortline@iastate.edu or 515-294-3108.
My bearded irises are no longer blooming well. Why?
The bearded irises may need to be divided. Bearded irises should be divided every three to five years as the plants
quickly become crowded and don’t bloom well. Mid-summer (July and August) is the best time to dig, divide and transplant
bearded irises.
Lack of sunlight could be another possibility. Bearded irises bloom best in full sun. Planting sites should receive at
least six hours of direct sun each day. Plants in partial shade may not bloom well and should be transplanted to a sunny site.
How do you divide bearded irises?
While bearded irises are easy-to-grow perennials, they need to be divided every three to five years. If not divided, plants
become overcrowded and flower production decreases. Crowded plants are also more prone to disease problems. In Iowa,
the best time to dig, divide and replant bearded irises is in July and August.
Bearded irises grow from thick, underground stems called rhizomes. Carefully dig up the iris clumps with a spade. Cut
back the leaves to one-third their original height. Wash the soil from the rhizomes and roots with a forceful stream of water
from the garden hose. Then cut the rhizomes apart with a sharp knife. Each division should have a fan of leaves, a healthy
rhizome and several large roots. Discard all diseased or insect damaged rhizomes.
Bearded irises perform best in fertile, well-drained soils and full sun. The planting site should receive at least six hours of
direct sun per day. When planting bearded irises, dig a hole large enough to accommodate the rhizome and roots. Build a
mound in the center of the hole. Place a rhizome on top of the mound and spread the roots in the surrounding trench. Then
cover with soil. When planted, the rhizome should be just below the soil surface. Finally, water each plant thoroughly.
To obtain a good flower display, plant at least three rhizomes of one variety in a group. Space the rhizomes 12 to 24
inches apart.
How do I control the iris borer?
The iris borer is a serious pest of bearded irises. The mature stage of the iris borer is a grayish moth. Female moths lay
eggs on iris foliage and other nearby plants in late summer/early fall. The eggs hatch the following spring. The small larvae
(caterpillars) bore their way into the iris foliage and feed on leaf tissue. Over time, the larvae tunnel down through the leaves
and into the rhizomes. The caterpillars continue to feed inside the rhizomes, eventually devouring much of the rhizome. When
fully grown, the larvae move into the soil and pupate. Adults (moths) emerge in late summer.
Bacterial soft rot often invades rhizomes damaged by iris borers. Rhizomes infected with bacterial soft rot become soft
and foul-smelling.
Iris borers can be controlled by sanitation and the timely application of insecticides. Remove and destroy dead iris foliage
in fall or very early spring. This will eliminate many of the iris borer eggs. Also, apply an insecticide in spring when the new
shoots are 4 to 6 inches long. An application of an insecticide at this time should destroy small iris borer larvae before they
have the opportunity to tunnel into the iris foliage. Products that contain acephate, permethrin or spinosad should be effective.
As always, carefully read and follow label directions when using pesticides.
There are small, brown spots on the foliage of my bearded irises. What is the problem?
The small, brown spots are likely due to iris leaf spot. Iris leaf spot is a common disease of bearded irises. The
disease is caused by the fungus Mycosphaerella macrospora. The first symptom of iris leaf spot is the appearance of small
yellow-brown spots on leaves that are surrounded by water-soaked borders. The spots eventually turn grayish brown, develop
reddish-brown borders and grow in size. As the spots grow, several spots may coalesce and destroy entire leaves. Iris leaf
spot is most severe when the weather in spring is cool and wet.
Good cultural practices will reduce the severity of iris leaf spot. Remove all diseased leaves and flower stalks in fall or
early spring. (The causal fungus survives the winter on infected plant parts.) Plant bearded irises in full sun, space plants
adequately, control weeds, and avoid wetting plant foliage when watering.
Fungicides will likely be necessary to control iris leaf spot on plants that were severely infected the previous year. The first
application should be made when the leaves first appear in spring. Continue to spray as directed on the product label.
Effective fungicide products include those that contain chlorothalonil and myclobutanil. Since bearded iris leaves are waxy,
add a spreader-sticker to the fungicide to make sure the fungicide adheres to the iris foliage.
Plant and Insect Diagnostic Clinic Update –
June 29, 2011
The following are highlights and updates about samples and questions recently received in the
Plant & Insect Diagnostic Clinic:
Insects
Millions of Migrating Millipedes Maraud the Midwest! We don't have anything new about
millipedes to add to the Update from June 14, 2011, other than to say, "Yep. They are still out there."
See the pictures below for how bad it can get!
Calls and messages continue to describe hoards of millipedes in the lawns, on the driveway and
patio, on the side of the house and indoors. The common question is, "When will they leave us alone?"
The short answer is, "We don't know, but hang in there." In the meantime, like we said last issue, "There
still is no silver bullet for millipede prevention. Perimeter barriers of insecticide around the house or other
building must be very large to accomplish any protection. None of our residual insecticides kill millipedes
quickly enough to "drop them in their tracks" after crossing an insecticide barrier of only a few inches
next to the house. See our website more more details."
The first report of Japanese beetles this year came on June 22. There has been a steady tickle
of calls and messages since then, but that should change to a torrent as we reach the peak of adult
emergence in mid-July. See the article elsewhere in this issue.
It's the time of the year to see dobsonflies. These huge, prehistoric-looking insects are
unmistakable. See the Plant & Insect Diagnostic Clinic article for details and photos.
Disease
We continue to receive lots of spruce with Rhizosphaera needle cast and stigmina needle
cast.
Ornamental plants with root rots are starting to trickle in as well. Although there are several fungi
that can cause root rots right now we are mostly seeing pythium.
High Tunnel Field Day at Armstrong Research Farm
Near Lewis
BY LINDA NAEVE
Proper Waste Management is an essential skill for fruit and vegetable high tunnel growers.
Since the plastic film covering prevents rain water from reaching the crop, the environment
underneath is virtually a desert. Water is typically provided by drip irrigation lines placed beside
the crops. Drip irrigation waters only the crop root zone, keeping the foliage dry which results in
less incidence of foliage diseases associated with water on the leaves.
However, an estimated 1,800 gallons of water runs off a 30 x 96 foot high tunnel with each
inch of rain. That volume tends to puddle around the sides of a high tunnel or requires drainage.
Rather than letting water create a saturated area around the high tunnel, erode the soil around
the high tunnel or go unused, Iowa State University Extension specialists have developed a
system to collect the rain water and store it for reuse on the crops in the high tunnel. The system
demonstrates a water collection system that was retrofitted on a Quonset style high tunnel with
both electric and solar powered pumps.
The public is invited to a field day to learn more about this system and see the production
and drip irrigation system in the high tunnel. The field day will be held on July 12 at 6:30 p.m. at
the Armstrong Research and Demonstration Farm, 53020 Hitchcock Avenue, Lewis, Iowa. The
farm is located 11 miles southwest of Atlantic.
For more information, contact Linda Naeve at 515-294-8946 or via email at
lnaeve@iastate.edu.
.
Upcoming Workshop Spotlights Beneficial Insects
BY MATT O'NEAL
AMES, Iowa – Farmers, researchers and native plant aficionados are invited to a one-day
workshop exploring how to enhance the ecosystem services provided by beneficial insects. Iowa
State University’s Departments of Entomology and Natural Resource Ecology and Management,
with support from the Leopold Center for Sustainable Agriculture, will host the workshop on
August 4.
Beneficial insects provide services like pollination and the suppression of pests. Farmers
and gardeners can encourage these insects by creating a refuge that supplies them a source of
pollen and nectar. At the workshop, participants will learn how to identify helpful insects and the
native plants that attract them. Experts will discuss how to create resilient landscapes that
provide multiple services, and federal and state programs that help support this form of
conservation.
Participants will have a chance to examine insect specimens and visit the Field Extension
Education Laboratory (FEEL), where researchers are testing the ability of native plants to attract
helpful species, like bees and lady beetles.
Speakers include Iowa State’s Lisa Schulte and Mary Harris, natural resource ecology and
management, Kelly Seman and Matt O’Neal, entomology, Meghann Jarchow, agronomy and
Practical Farmers of Iowa representative, Sarah Carlson.
The workshop will take place at FEEL, five miles west of Ames. Register by July 15 at
www.aep.iastate.edu/ent. Reduced hotel rates are available for out-of-town visitors through the
ISU Memorial Union. Lunch will be provided.
How Hard are the Scale Insects?
It's a funny question, all right, but one that turns out to be more important than you might suppose. Scale
insects are sap-feeding insects named for the scale or shell-like waxy covering that conceals their bodies.
Scale insects are generally divided into two categories: soft scale and armored (hard) scales. The names
are moderately descriptive of the group, but not entirely, nor does hardness versus softness describe the whole
difference.

Soft scales produce a soft, thin, cottony, powdery or waxy layer over themselves that cannot be
separated from the insect body. These scale insects often produce copious amounts of honeydew.

Armored scales have a hard, shield-like cover composed of shed skins and wax that conceals the body
but is not attached to the body of the insect.
In Iowa, most species of shade trees, fruit trees, and ornamental shrubs are subject to scale insect attacks.
Depending on the species, scale insects may be found on plant stems, twigs, trunks, foliage, or fruit. Most scale insects
are small and inconspicuous. The size of scale insects ranges from 1/8 to ½ inch. Color, shape, texture and other
features vary with the species. Scale insects can weaken and even kill trees, shrubs and houseplants, but in general,
complete loss of the plant is rare.
Scale insects feed by sucking sap from trees and shrubs through piercing-sucking mouth parts. Sap feeding by
scale insects may cause yellowing or wilting of leaves, stunting or unthrifty appearance of the plants, and eventually
death of all or part of the plant when infestations are heavy. Weakened plants may lose vigor and become more
susceptible to injury caused by drought, severe winters, attack by other insects (such as borers), or infection by
diseases.
While feeding, soft scale insects excrete a sweet, sticky substance called honeydew. Honeydew is a mixture
of undigested sugar and water passed through the insect's digestive system and deposited onto leaves and
stems. Honeydew may make the plant appear shiny and wet and also attracts flies, ants, bees, and other insect
scavengers. The honeydew may encourage a fungus called sooty moldthat gives the plants a characteristic black,
“sooty” appearance. Honeydew can foul sidewalk, cars, and houses beneath scale-infested trees.
Life Cycle
Scale insects have a simple life. Eggs are laid underneath the scale covering of the adult female. When the
eggs hatch, tiny immatures, known as nymphs, emerge. Nymphs have legs and antennae and are called “crawlers”
because they walk away from the maternal scale to settle at new feeding sites. For most common scales, this is the only
stage that crawls about on the plant. When the crawlers arrive at a suitable location, they insert their mouthparts into the
plant, and begin to feed on the plant’s sap. The shell or scale characteristic of the species develops soon after feeding
begins. The legs and antennae of most species are lost as the nymphs grow.
Nymphs and adult females for most species remain at the same location for the rest of their lives. Adult males
are tiny, flying, gnat-like insects that fly to new females for mating. Scales may go through one or more generations
each year.
For more on scale insects found in Iowa, see ISU Extension publication IC-415, Scale Insects on Ornamental
Plants.
Here is a brief list of the common soft and armored scales of ornamenal plants in Iowa.
Conifer Plants
Soft Scales
Pine Tortoise Scale
Spruce Bud Scale
Fletcher Scale
Armored Scales
Pine Needle Scale
Deciduous Plants
Soft Scales
Cottony Maple Scale
Lecanium Scales
Armored Scales
Oystershell Scale
Euonymus Scale
Scurfy Scale
San Jose Scale
Dividing Bearded Irises
Bearded irises are one of the most popular and widely grown perennials in the home
landscape. While bearded irises are beautiful, they do require high levels of maintenance. One
important chore is to divide bearded irises every 3 to 5 years. If not divided, the plants become
overcrowded and flower production decreases. Crowded plants are also more prone to foliar
diseases. The best time to dig, divide, and replant bearded irises is in July and August.
Bearded irises grow from thick, fleshy, underground stems called rhizomes. Carefully dig
up the iris clumps with a spade. Cut the leaves back to 1/3 their original height. Wash the soil
from the rhizomes with a forceful stream of water from the garden hose. Then cut the rhizomes
apart with a sharp knife. Each division should have a fan of leaves, a healthy rhizome, and
several roots. Discard the old, leafless rhizomes in the center of each clump. Also, discard all
diseased and insect damaged rhizomes.
Bearded irises perform best in fertile, well-drained soils and full sun. The planting site
should receive at least six hours of direct sun per day. Plants that don't receive sufficient
sunlight will not bloom well. Bacterial soft rot is often a problem in wet, poorly drained sites. Wet,
poorly drained sites can often be improved by incorporating organic matter, such as sphagnum
peat moss or compost, into the soil prior to planting. Raised beds are another option for
gardeners with poorly drained soils.
When planting bearded irises, dig a hole large enough to accommodate the rhizome and
roots. Build a mound in the center of the hole. Place a rhizome on top of the mound and spread
the roots in the surrounding trench. Then cover with soil. When planted, the rhizome should be
just below the soil surface. Finally, water each plant thoroughly.
To obtain a good flower display, plant 3 or more rhizomes of one variety in a group. Space
the rhizomes about 12 to 24 inches apart. Point each fan of leaves away from the other irises in
the group.
Divided irises typically bloom sparsely the following spring. However, plants should be
in full bloom by their second year.
By Richard Jauron, Department of Horticulture
Japanese Beetles. They're Ba-a-a-ck!
Like swallows returning to San Juan Capistrano, the Japanese beetles have reappeared on
Iowa's roses and grape vines. Sigh. Here we go again.
See the June 23, 2010 Horticulture and Home Pest News for a complete review of the Japanese
beetle biology and control.
On second thought, Japanese beetles are not like swallows, since the Japanese beetles never
went anywhere. They've been underground as larvae since last summer. They are not returning from
somewhere else, but their timing is as dependable as that of the famed swallows.
We continue to monitor and document the spread of the Japanese beetle within Iowa. Six
counties where Japanese beetles were not previously reported were added to our list in 2010 via the
bean pod mottle virus/bean leaf beetle survey coordinated by Forrest Nutter in the Department of Plant
Pathology and Microbiology. The 6 new counties were Audubon, Carroll, Cherokee, Hamilton, Harrison
and Ida. The current, reported distribution of the Japanese beetle is shown in the accompanying map. If
you find beetles that you suspect are Japanese beetles, please send specimens or digital images to
Extension Entomology, ISU, Ames IA 50011 (insects@iastate.edu) for confirmation and recording as a
new county record.
Reported distribution of the
Japanese beetle in Iowa, December, 2010.
Speaking of San Juan Capistrano reminds me of the guy who walked into the bar and asked the
bartender for a Capistrano martini. "What's a 'Capistrano martini'?" replied the bartender. The guy
answered, "It starts at dawn and it's just one swallow after another."
Harvesting and Storing Small Fruits
Harvesting small fruits at the correct stage of maturity and proper storage are vital to insure high quality. Small
quantities of fresh fruit can be stored in the refrigerator for a short time. Surplus fruit should be canned or frozen. While
personal preferences vary somewhat, use the following criteria to harvest small fruit crops at their peak of quality and
flavor.
Strawberries
Harvest strawberries when the fruit are uniformly red (fully ripe). Pick the berries with the caps and stems
attached to retain firmness and quality. Pinch off the stem about one-fourth inch above the cap. Don't pull the fruit from
the plant.
Strawberries should be picked about every other day in warm weather, every three to four days in cool
weather. The harvest period for some June-bearing varieties may last three to four weeks. Strawberries can be stored in
the refrigerator for up to five to seven days. Optimum storage conditions are a temperature of 32 degrees Fahrenheit
and a relative humidity of 90 to 95 percent.
Raspberries
Raspberries are ripe when the fruit are fully colored. Also, ripe berries slip easily from their cores or
receptacles, which remain on the plant. If possible, harvest in the early morning hours before heat builds up in the
fruit. Raspberries are very perishable. When harvesting, handle the berries carefully. Refrigerate or freeze the fruit
immediately after harvest. The maximum storage life of raspberries is two to three days at a temperature of 31 to 32
degrees Fahrenheit and a relative humidity of 90 to 95 percent.
Blackberries
Harvest blackberries when the fruit develop their characteristic black color and flavor and become soft. Harvest
every three to five days. Blackberries can be stored for two to three days at a temperature of 31 to 32 degrees
Fahrenheit and a relative humidity of 90 to 95 percent.
Blueberries
Harvest blueberries when the fruit are fully ripe. The best indications of ripeness are color, flavor, and picking
ease. Fully ripe blueberries are uniformly blue in color, have a good flavor, and separate easily from the plant. (Do not
harvest blueberries on color alone, as the berry is often blue for some time before being fully ripe.) After harvesting,
immediately store blueberries in the refrigerator. Maximum storage life is seven to ten days.
Grapes
Grapes should not be harvested until fully ripe. The best indicators of ripeness are color, size, and flavor.
Depending on the variety, berry color changes from green to blue, red or white as the grapes approach
maturity. At the fully ripe stage, the natural bloom on the berries becomes more pronounced. However, color should not
be the sole basis for harvesting grapes. Many varieties change color long before the grapes are fully ripe.
Size and firmness are other useful indicators of ripeness. The individual berries should be full-sized. They also
become slightly less firm to the touch at maturity.
The final and most reliable test for ripeness is flavor. Taste a few grapes when size and color are good. If they
are not sweet, leave the clusters on the vines. Grapes do not develop full flavor when harvested before completely
mature.
Harvest grape clusters with a scissors or hand shears. Grapes can be stored in the refrigerator for one to two
weeks at a temperature of 32 to 36 degrees Fahrenheit and relative humidity of 90 to 95 percent.
Currants
Currants typically ripen over a two-to-three-week period. Fully ripe currants possess the characteristic color of
the variety (red, white, or black), are slightly soft and juicy. For jellies and jams, harvest currants before the berries are
fully ripe. Fruit harvested for jellies and jams should be well-colored, but still firm. Natural levels of fruit pectin are higher
in berries that are not fully ripe. Harvest currants by picking the fruit clusters (strigs) rather than the individual
berries. After picking, the individual berries can be stripped from the stems. Currants can be stored in the refrigerator at
35 to 40 degrees Fahrenheit for approximately two weeks.
Gooseberries
For jams, jellies, and pies, most gardeners pick gooseberries when they have reached full size, but are not fully
ripe. At this stage, the fruit are green, tart, and still quite hard. Others prefer to allow the fruit to ripen to a pinkish color
and sweeter flavor. Gooseberries can be refrigerated at 35 to 40 degrees Fahrenheit for approximately two weeks.
Elderberries
Fully ripe elderberries are plump, slightly soft, and dull purple in color. For jelly, harvest the berries when only half
ripe. Elderberries are borne in large, flat clusters. The berries mature in mid-summer. Elderberries can be stored for one
to two weeks at a temperature of 31 to 32 degrees Fahrenheit and a relative humidity of 90 to 95 percent.
Spruce and Other Conifers Continue to Struggle
It just seems like one thing after another with conifers. For years we have dealt with
stressed conifers due to excessive soil moisture. Iowa has been in a weather pattern of
increased spring rainfall for several years. Large amounts of rain that saturate the soil for
long periods are problematic for some trees. Conifers especially need well drained soils. If
they are planted in a clay soil or any areas where soil can remain saturated for even short
time periods conifers will experience root damage. Root damage prevents the tree from
uptaking water when they need it. As a result, we often see browning of needles and
needle drop (Figure 1), which also occurs with some needle cast diseases that affect
spruce.
This spring we have received a lot of samples with Rhizosphaera needle cast
(Figure 2). The wet weather is a bit of a double whammy to the spruce as it harms the tree
and benefits fungal diseases. We have continued to get lots of samples of spruce,
concolor firs, white pine with browning needles that is likely due to root damage.
In the past couple of weeks we are also getting samples with the new growth brown
and dead (Figure 3). There have been reports of herbicides causing problems for conifers,
particularly spruce and white pine. Please see these articles for more information:
Imprelis damage on trees - Iowa
Growth Regulator-Type Herbicide Symptoms on Spruce and Pine - Indiana
Ornamental Plant Damage Reports Increase - Ohio
There have also been many samples from areas where no herbicides were used
and so it is most likely environmental. We think that possibly the very hot weather and
winds we had earlier this spring combined with damaged roots made it very hard for trees
to keep up with the water needs of the new growth.
Turf anthracnose
The ISU Plant & Insect Diagnostic Clinic has started to receive our first turf samples
this season. It seems that the warm and humid weather conditions these past weeks have
favored infection by a number of diseases on turf, including anthracnose.
Anthracnose on turf is caused by a fungus called Colletotrichum graminicola. This
fungus is commonly found on dead or decaying organic matter, but when the conditions are
right, it can cause foliar blight and basal rotting on almost all turf grass species.
Plants with foliar symptoms (foliar blight) sometimes show distinct leaf lesions,
and as symptoms progress, older leaves may turn brown (Figure 1). When the fungus attacks the
base of the plants, rotting and blackening of the crown (lower stem) may occur. Leaves will turn
yellow and become water-soaked, but usually they won’t have any distinct leaf spots. When seen
under a microscope, prickly cushion-like structures produced by the fungus (called acervuli) can
be seen on infected tissues (Figure 2). Eventually, infected plants turn completely brown and die.
From a distance, you may see yellow thinning patches with no definite shape (Figure 3).
Disease infection is favored by stressed out plants. Plants with root problems or
reduced vigor make them an easy target for the fungus. Therefore, the best way to control this
disease is by avoiding stressful conditions on your lawn. Make sure that your lawn is getting
proper fertilization and avoid applying high nitrogen rates during dry periods or high
temperatures. Improve drainage and when watering, water thoroughly but not too frequently.
Also, increase mowing height and reduce mowing frequency.
Alternate Bearing and Hand Thinning of Tree Fruits
The tendency of fruit trees to bear fruit in two-year cycles, consisting of a large crop
followed by a small crop, is termed alternate or biennial bearing. Alternate bearing occurs in
almost all tree fruits.
The flowers that produce next year's crop are initiated during the development of the
current season's crop. When a fruit tree is producing a large fruit crop, most of the tree's energy
is utilized for fruit development, little energy remains for flower initiation. As a result, a fruit tree
often produces a small number of flowers and fruits when preceded by a heavy crop the previous
year.
To discourage alternate bearing, home gardeners should thin apple and other fruit trees
when fruit set is heavy. Thinning also promotes the development of large, high quality fruit at
harvest and prevents limb breakage on trees heavily laden with fruit.
Hand thinning of apples should be done within six weeks of full bloom. Leave the largest
apple in a cluster unless it is damaged. After thinning, apples should be spaced about 8 to 10
inches apart on the branches. Pears, apricots, and peaches may also need to be thinned. Fruit
should be spaced 6 to 8 inches apart on the branches. Plums will generally thin themselves.
Fungicides and How to Use Them Effectively
Viruses, nematodes, and bacteria can cause plant disease, but fungi are the number one diseasecausing organism. As a result, fungicides are frequently used by homeowners when managing plant
disease problems.
Fungicides are pesticides that can kill or inhibit growth of fungi on plants, but they are not
effective against bacteria, nematodes, or viral diseases. Fungicides can be classified based on if they are
absorbed by the plant and if they can move around in plant tissues, their 'curative' properties, how they
kill the fungi (mode of action), and type of chemical. Some of the major categories are described below:
1. Contact vs systemic: Contact fungicides (protectants) are not absorbed by the plant and stick to
plant surfaces. They provide a protective barrier that prevents the fungus from entering and
damaging plant tissues. Systemic products (also known as penetrants), are absorbed by the plant
and are able to move from the site of application to other parts of the plant.
2. Preventive vs curative: Preventive fungicides work by preventing the fungus from getting into the
plant. The preventive fungicide must come into direct contact with the fungus and they have to be
re-applied to new plant tissues (as leaves or needles expand in the spring) or if the product washes
off. Curative fungicides affect the fungus after infection. This means they have the ability to stop
the disease after the infection has started or after first symptoms are observed.
3. Mode of action: This refers to how the fungicide affects the fungus. Fungicides may work by
damaging the cell membrane of the fungus, or by inhibiting an important process that the fungi. It's
important to incorporate different modes of action by mixture or by alternating products to maintain
effectiveness and prevent fungicide resistance.
4. Chemical group: this classification may vary depending on chemical composition, structure, and
mode of action.
Rules of thumb for fungicide use
For efficient and safe fungicide use, certain rules have to be followed. First, the problem has
to be diagnosed correctly. Before applying a fungicide make sure that you know the cause of the
disease (that is a diseases caused by a fungus). Second, read the label and follow instructions.
This will not only protect your plant, but it will also protect your health and the environment.
Remember always to apply fungicides using the appropriate equipment at the recommended
application rate. Third, follow the recommendations of when and how often to apply the fungicide.
Timing of the fungicide application can enhance the effectiveness of the product and prevent
additional sprays.
Fungicide labels should provide information on recommended use, ingredients, mode of
action, and formulation of the product. For more information please see University of Kentucky
Extension bulletin ID100.
Remember that the best management strategy against plant diseases is by promoting plant
health in the first place. Before planting, make sure that soil, water, and light conditions are ideal
for your plant. Once the plants have been established, make sure to use the appropriate sanitation,
fertilization, and pruning practices to enhance plant health.
Upcoming Items and Events:
Tuesday, July 19, 2011
4:00 PM - 5:00 PM Montgomery County Fair sheep weigh in Red Oak--Fairgrounds
4:00 PM - 5:45 PM Montgomery County Fair poultry weigh in and check in Red Oak--Fairgrounds
5:00 PM - 6:00 PM Montgomery County Fair goat weigh in and check in Red Oak--Fairgrounds
7:30 PM - 8:30 PM Montgomery County Fair opening ceremony Red Oak--Fairgrounds
Wednesday, July 20, 2011
6:30 AM - 9:00 AM Montgomery County Fair swine weigh in Red Oak--Fairgrounds
7:00 AM - 9:30 AM Montgomery County Fair rabbit check in and weigh in Red Oak--Fairgrounds
8:00 AM - 12:00 PM Montgomery County Fair dog show Red Oak--Fairgrounds
2:00 PM - 6:00 PM Montgomery County Fair poultry show Red Oak--Fairgrounds
3:00 PM - 4:30 PM Healthy Meals in a Hurry Red Oak --Fairgrounds
6:30 PM - 8:30 PM Montgomery County Fair 4-H Night program Red Oak—Fairgrounds Auditorium
Thursday, July 21, 2011
6:30 AM - 8:30 AM Montgomery County Fair Beef weigh in and check in Red Oak--Fairgrounds
8:00 AM - 1:00 PM Montgomery County Fair rabbit show Red Oak--Fairgrounds
8:30 AM - 9:00 AM Weigh-in 4-H bucket calves Red Oak--Fairgrounds
2:00 PM - 5:00 PM Montgomery County Fair 4-H/FFA sheep show Red Oak--Fairgrounds
6:30 PM - 9:00 PM Montgomery County Fair 4-H/FFA Goat show Red Oak--Fairgrounds
Friday, July 22, 2011
8:00 AM - 12:00 PM Montgomery County Fair 4-H/FFA swine show Red Oak--Fairgrounds
3:30 PM - 5:30 PM Montgomery County Fair 4-H/FFA Livestock Judging Contest Red Oak--Fairgrounds
Saturday, July 23, 2011
8:00 AM - 12:00 PM Montgomery County Fair 4-H/FFA beef show Red Oak--Fairgrounds
2:00 PM - 3:00 PM Montgomery County Fair 4-H bucket calf show Red Oak--Fairgrounds
4:00 PM - 5:00 PM Montgomery County fair other animals show Red Oak--Fairgrounds
5:00 PM - 6:00 PM Montgomery County Fair 4-H Pet Show Red Oak--Fairgrounds
Sunday, July 24, 2011
11:00 AM - 12:00 PM Montgomery County Fair open class pet show Red Oak--Fairgrounds
4:00 PM - 7:30 PM Montgomery County Fair 4-H/FFA livestock auction Red Oak--Fairgrounds
9:00 PM - 11:30 PM Montgomery County Fair Teen Dance Red Oak—Fairgrounds Auditorium
Monday, July 25, 2011
8:00 AM - 12:00 PM Montgomery County Fair clean up day Red Oak--Fairgrounds
Tuesday, July 26, 2011
6:30 PM - 8:30 PM Master Gardener Webinar on Tall grass prairies Red Oak—Extension Office
Wednesday, July 27, 2011
5:30 PM - 6:30 PM SESS air rifle practice Red Oak—Goldsmith Gallery
Sunday, July 31, 2011
2:00 PM - 3:00 PM SESS rifle practice Stanton—David Olson’s place
3:00 PM - 4:00 PM SESS Shotgun practice Red Oak—David Olson’s place
Montgomery County Extension Office
400 Bridge Street, Suite 2
Red Oak, IA 51566
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