Download The Master Gardener Wet Weather Results in Plant Diseases June 2009

The Master Gardener
Volume 16, Issue 6
June 2009
Wet Weather Results in Plant Diseases
The wet weather in many parts of southern Illinois has certainly been
good for grass growth. But wet, humid weather is also good for plant
diseases. As a result, some plant diseases are quite common this year.
Anyone who has not been regularly treating their apple tree probably has
numerous rust and scab lesions on the leaves. The same is true for peach
leaf curl infections on untreated peach trees as well as leaf spots on
strawberries. While a few lesions on an occasional leaf is not a big deal,
infections on numerous leaves will cause premature defoliation and a
reduced crop.
Wet weather diseases are common on many plant species. Examples
include powdery mildew on many plants; tip dieback (diplodia) on pine
trees; black spot on roses; leaf spots on many plants (flowers, trees,
strawberries, tomatoes, etc.); and anthracnose leaf disease on
many plants.
In some cases, these diseases will not harm plant growth; but, severe
infections can cause irreparable damage. The level of damage
depends upon many factors—including the age of the plant, the plant’s
overall health, the infection level, and the severity of disease.
Shelby County
1125 W N 2nd Street
Shelbyville, IL 62565
Jim Looft
County Director
[email protected]
Ellen Trainor
Program Coordinator
[email protected]
Tel: 217-774-9546
Fax: 217-774-9549
Office Email:
[email protected]
Web:
www.extension.uiuc.edu/shelby
If the problem is severe, treatment may be necessary. But, remember that
an accurate diagnosis is key. If you need help diagnosing a problem for a
client, your local Extension office can connect you with an educator or
specialist for assistance.
Also, remind clients that
they need to help plants
remain as healthy as
possible. Improving air
circulation, mulching,
and providing nutrients
will go a long way
toward keeping plants
healthy. And, of course,
planting diseaseresistant varieties is
always a good idea.
In this Issue
A Close-Up Look at
Local Food Production
Bagworm Control
EAB and Other Ash
Tree Problems
When Is a Bushel
Really a Bushel?
Tours Offer Close-Up Look at Local Food Production
University of Illinois Extension is offering two informative tours in the region
this month. Spread the word to interested clients . . .
Organic Farming
Friday, June 12
12:30 – 4 P.M.
Farmer Browns Produce, Pomona
Clear Creek Farm, Cobden
The focus of this tour is on organic
food production and choosing
whether to certify. You’ll see a
diversified organic operation and
niches such as garlic varieties
valued by area chefs. You’ll also
learn about the community
supported agriculture model of
direct marketing.
Cost for the tour is $10 per person.
For registration and details, visit
http://asap.sustainability.uiuc.edu/
and click on Organics in the topics
column, or contact Dan Anderson at
217-333-1588.
Growing Strawberries Naturally
Friday, June 19
9 A.M. – 1 P.M.
Jed’s Farm, Thompsonville
Judy and Ernie Duckworth will
showcase their way of growing
strawberries, which includes fewer
chemicals and a longer growing
season. They use black plastic with
compost that is made from the
manure in their cow/calf operation,
rather than the methyl bromide that
many other fruit growers use.
Only three acres of the 80-acre farm
are devoted to a fruit and vegetable
operation. But, the Duckworths say
that the strawberries are more
lucrative than their cows.
During the lunch that follows the
tour, John Pike, U of I Extension
community and economic
development educator, will discuss
marketing specialty crops.
Advance registration by June 12 is
needed. The fee is $20, which
includes lunch. You can register
online or by phone:
For credit card payment, visit http://
web.extension.uiuc.edu/smallfarm/
ag_tours.cfm.
To pay by cash or check, call the
Franklin County Extension Office,
618-439-3178.
Early Bagworm Control Vital
Bagworms feed on the leaves of
evergreens such as white pine, blue
spruce, and red cedar. They can also
be found on cypress and other
deciduous trees.
The bag is made of silk and bits of
twigs and leaves of the host plant.
Active bags will have green leaves
or needles on the top. The bag
enlarges as the caterpillar grows.
As bagworm caterpillars mature,
they hang like ornaments. Damage
is most severe on evergreens, where
leaf loss can cause branch death.
The trouble is often we don’t notice
the bags and the damage until late
in the season when hand picking the
bags is the only option.
In southern Illinois, bagworm egg
hatch occurs in June. Pesticides are
most effective if applied two weeks
after egg hatch. Control should
begin in mid-June. An additional
application is advised one to two
weeks later to control caterpillars
that emerge later.
The female produces 500 to 1,000
eggs in one bag, which can result in
large populations on a single plant.
U of I Extension suggests these
options for bagworm control:
Bacillus thuringiensis kurstaki
(sold as Dipel or Thuricide), and
insecticides with cyfluthin.
The Master Gardener—2
Insecticide sprays are effective
against the young larvae, but bags
that are 3/4 inch long or longer are
difficult to control. The bacterium
Bacillus thuringiensis is effective on
young caterpillars, but the material
must be ingested—so thorough
plant coverage
is essential.
Cyfluthrin is
recommended
for larger
larvae, but
again,
thorough
coverage is
necessary.
Be on the Lookout for EAB and Other Ash Tree Problems
If you’ve seen a purple contraption
that resembles a box kite hanging
from a tree, it’s likely an Emerald
Ash Bore (EAB) trap. The Illinois
Department of Agriculture has
placed approximately 5,000 EAB
traps throughout the state.
The traps primarily are concentrated
in a 50-mile buffer zone that runs
along the state’s western border
from northern to central Illinois and
then cuts a swath across the southcentral part of the state to the
Indiana border in southeast Illinois.
The Ag Department asks that these
traps be left alone.
EAB is an invasive beetle that has
devastated tens of thousands of ash
trees in Illinois since it was first
discovered in the state in 2006.
The Emerald Ash Borer is a small
metallic -green insect, about onethird to one-half the size of a penny.
Adults can fly but not for long
distances. The borer will tunnel
under the bark and start feeding on
the sapwood of the tree, causing
leaves to thin and yellow.
Besides the color, D-shaped holes
on the bark are another clue. No
other insect creates the BB-size,
D-shaped holes on ashes. Also,
trees may produce shoots around
the trunk at ground level.
There are other metallic -green
insects, including many beetles,
which can make identification of
EAB more difficult. The false June
bug is a common metallic -green
beetle, though it is almost the size
of a quarter. Japanese beetles are
metallic green as well, but with a
coppery overtone.
Compounding the problem, ashes
are plagued by other insects
The Master Gardener—3
including another ash borer and
sapsuckers, all of which can cause
holes in the trunk of the tree and
lead to a decline in the overall
health of the tree, including the
yellowing and thinning of the
leaves. Homeowners need to look
carefully to determine the cause.
Sapsuckers (a type of woodpecker)
create uniform rows of round holes
up and down the tree’s trunk. The
sapsucker is a protected migratory
bird, so control is limited.
Lilac/Ash Borer is a moth that looks
almost wasp-like. The caterpillar
tunnels beneath the bark on both
lilacs and ashes. Females lay eggs
on the bark, and the larvae tunnel
beneath and start feeding during late
May and early June. The presence
of fine sawdust material called frass
is an indication of tunneling. The
holes made by this insect are round
instead of D-shaped.
Several diseases and environmental
factors can also create problems.
Anthracnose, a common spring
fungal disease, causes leaves to
become twisted, water-soaked, and
turn olive-green; then, the leaves
fall off. Usually, the tree will
produce more leaves, so the longterm effect is minimal.
Horticulturists and plant
pathologists haven’t been able to
isolate a causal agent, though
some suspect a microorganism.
Ash Decline could also be confused
with the effects of Ash Yellows or
fungal Verticillium Wilt.
A multi-step approach is needed to
protect ash trees:
• Maintain the health and vigor of
ash trees. Like most plants, trees
under stress are more likely to be
infested by insects or infected
with diseases. Water during
droughts and maintain proper
nutrient levels. Mulch the tree out
to the drip line to avoid mower
injury and grass competition.
• Avoid planting ash trees. While
ashes are fast-growing, strong
wood shade trees, they suffer
several problems. If the Emerald
Ash Borer moves further through
the state, expect damage to occur.
Work with your local nursery or
garden center on alternatives to
ash trees.
• Be vigilant. Look for D-shaped
holes and the small emeraldgreen adult borer. Check trees
regularly, particularly in the
spring and early summer.
• Be open-minded. Remember, not
Ash Decline is a name for a group
every problem with the ash tree is
of symptoms. The term is used to
caused by the EAB. It’s wise to
describe the overall decline of the
be concerned, but don’t get to the
tree, starting with dieback of
point of crying wolf.
branches and limited new growth.
Leaves may be sparse, giving the
• If you do suspect Emerald Ash
tree a sickly appearance. Trees
Borers, contact your local U of I
generally don’t die abruptly.
Extension office.
Instead, they may decline over
five to 10 years. Trees
seldom produce any
To learn more, log on to SI Gardening,
shoots at ground level
http://web.extension.uiuc.edu/regions/hort
next to the trunk.
and click Pests and Diseases.
Shelby County
1125 W N 2nd Street
Shelbyville, IL 62565
We’re on the Web!
www.extension.uiuc.edu/shelby
Helping You Put Knowledge to Work
Articles written by U of I Extension
staff: David Robson, Mike Roegge,
Ed Billingsley, Annette Campbell
University of Illinois~U.S. Department of Agriculture~Local Extension Councils Cooperating
University of Illinois Extension provides equal opportunities in programs and employment.
If you need special dietary or disability accommodations to participate in any events listed
in this newsletter, please contact your local U of I Extension office.
The information in this newsletter is for educational purposes only.
References to commercial products and trade names do not constitute endorsement by the
University of Illinois and do not imply discrimination against other similar products that are not listed.
When is a Bushel of Produce Really a Bushel?
You’re at a local farmer’s market
eyeing a bushel of vegetables or
fruits, and you start to wonder if it
truly is a bushel.
A bushel of produce is a bushel
when it meets the legal standard
of volume of dry measurement
containing four pecks, 32 quarts, or
2,150.42 cubic inches. Anything
less than this volume is not a
bushel, and consumers should be
aware of small containers or
amounts advertised as bushels.
In other words, a bushel is an
amount based on volume and not
weight. It’s what the box or basket
will hold rather than how much it
weighs —a big difference!
Years ago, laws included legal
weights for bushels of commodities.
As varieties and grade sizes
changed, so did the density and
weight of the produce. Many of the
legal weights became outdated.
Today produce may be sold by
volume in open containers and net
weight in closed containers.
The bushel container is a carryover
from days of yesteryear, when the
bushel was a convenient volume of
packing and use. Now it is less
common because of the demand for
smaller containers and improved
quality control. But, many farm
markets, roadside stands, and
terminal markets still sell by the
bushel— using baskets, boxes,
and hampers.
In Illinois, commonly accepted
weights in pounds per bushel for
fruits and vegetables are as follows:
apples, 42–48; grapes, 44–50;
peaches, 48–52; pears, 48–50; green
beans, 28–30; cucumbers, 4–50;
greens, 18–20; and tomatoes,
50–60. Consumers buying by the
pound can convert to bushel prices
by using these weights.
Other common produce containers
for volume sales are pecks, quarts,
and pints. Most of the pecks of fruit
should weigh 10 to 12 pounds,
whereas pecks of vegetables are
quite variable due to differences in
texture and weight of the crop.
Quarts of small fruits such as
strawberries, raspberries, and
blueberries weigh 1.4 to 1.5 pounds.