Download The Master Gardener Are Spider Mites Infesting Your Plants?

The Master Gardener
Volume 17, Issue 1
January 2010
Are Spider Mites Infesting Your Plants?
If the foliage on your houseplants is a bit off-color, and there are fine webs
all over the plant, the culprit is the two-spotted spider mite, a common pest
often discovered this time of year on our indoor plants.
Spider mites are so called because of the web they build. They are small,
about the size of the period at the end of this sentence. They are not insects,
but belong to the Arachnid class along with spiders and ticks. They have
four pairs of legs instead of three, and lack antennae and jaws.
Shelby County
1125 W N 2nd Street
Shelbyville, IL 62565
Jim Looft
County Director
[email protected]
Mites damage plants by piercing plant tissue with their needlelike mouthparts and sucking out sap and cell contents. This results in tiny needle -like
puncture marks that, when numerous, give the leaf an overall silver or
yellow cast. Upon closer examination, you see fine webbing. This webbing
often starts on the underside of leaves. By the time webs have encased an
entire leaf, spider mite numbers are high. Unchecked, mite infestations can
lead to bronzing of foliage and premature leaf drop.
Ellen Trainor
Program Coordinator
[email protected]
Two-spotted spider mites are hard to detect at first when their numbers are
low. We usually don’t notice them until their numbers are so great we see
the webs they create. Over the holidays, we tend to pay less attention to our
houseplants. They are often moved and bunched together in a makeshift
location. Here, an infested plant quickly spreads this pest. Two-spotted
spider mites spread through direct contact from plant to plant. If you
pushed your plants close together for the holidays, spider mites dropped
from plant to plant.
Office Email:
Spider mite infestations are easier to prevent than control. Most insecticides
are ineffective because mites are not insects. In general, mites prefer high
temperatures and low humidity. Your first line of defense is to avoid these
conditions. Ample moisture and high humidity lowers mites’ feeding.
Misting of foliage or placing the plant on top of a shallow container of rocks
and water helps increase the humidity in the immediate surrounding area.
Never introduce a new plant without some type of quarantine time period
to determine if it is or isn’t infested. Inspect the undersides of leaves,
particularly along the midrib. Check the middle -aged leaves first since mite
infestations seem to begin on such leaves. If a plant is found to be infested,
the best treatment is insecticidal soap. Read and follow all label instructions,
making sure your plant is listed on the label. You will be instructed to repeat
application until mite activity ceases.
Tel: 217-774-9546
Fax: 217-774-9549
[email protected]
Web:
www.extension.uiuc.edu/shelby
In this Issue
Spider Mites
Ordering Sweet Corn Seed
Opportunities for Learning
Rex Begonia Offers
Gorgeous Foliage
Read This Before Ordering Sweet Corn Seed
When you are selecting sweet corn
cultivars for the upcoming growing
season, you will see abbreviations
like “su,” “se,” and “sh2” in the
description that follows the cultivar
name. We have all seen these
abbreviations, but do we know what
they mean and what implications
they carry? Here’s a rundown to
help you make your selections.
Normal sugary (su) sweet corns
require careful harvesting and
handling to preserve sweetness and
flavor. This type accounts for many
of the older cultivars and has the
traditional sweet corn flavor and
texture. The overall sugar content
depends on the cultivar; but in
general, “su” cultivars accumulate
two times more sugar than standard
field corn.
These cultivars lose their sweet
flavor very quickly after harvesting
because sugars quickly convert to
starch—so, they should be
refrigerated or immediately
consumed to take full advantage of
their old-time flavor.
To avoid cross-pollination and poor
quality, su cultivars should be
isolated from field corn and
popcorn by at least 250 feet. They
must also be isolated from the
supersweet group (sh2 and
Augmented Shrunken).
Sugary enhanced (se) sweet corn
cultivars have a kernel with
increased sugar content and
tenderness to varying degrees.
The higher sugar levels result in
cultivars that maintain their quality
over a longer period of time
compared to su types.
The Master Gardener—2
The se types are most common in
local markets because the sweetness
lasts longer, the kernels are easy to
chew, and they have a creamy
texture and good corn flavor.
Sugary enhanced cultivars do not
require isolation from su cultivars,
but they do require isolation by at
least 250 feet from the sh2 group
(sh2 and Augmented Shrunken),
field corn, and popcorn.
Supersweet corn cultivars, also
known as sh2 or shrunken types, can
have two to three times the sugars
of the regular su types; they get
their name from the appearance of
the dried kernel. The kernels are
characterized by high sugar content
and a very crisp texture. Some
people prefer the more tender se and
su types; however, most find the
crisp texture pleasing as long as it
doesn’t get tough and chewy.
Cultivars have
been developed
that have different
combinations of
the three major
genes (and their
modifier genes)
‘stacked’
together. The goal
of this breeding
effort is to put together the best
characteristics from the su, se, and
sh2 genes.
Synergystic sweet corn cultivars
combine the characteristics of both
supersweets (sh2) and sugary
enhanced (se) types, and include
cultivars under branded names like
Sweet Breeds TM and TriplesweetTM.
Synergystic sweet corn cultivars
should be isolated from sh2 and
Augmented Shrunken, and for best
results, should also be isolated
from su.
The conversion of sugars to starch
is also much slower, making this
type more suitable for longer
storage and long-distance shipping.
The main drawback of sh2 cultivars
has been their inability to withstand
cold, wet conditions; hence,
growers generally should plant the
sh2 types later than other types.
Another new type is the Augmented
Shrunken cultivars, which have
long-lasting high sugar contents like
sh2 cultivars, but the kernels are
extra juicy and tender like se
cultivars. This type includes
cultivars under branded names like
Gourmet SweetTM, MultisweetTM,
and Xtra-Tender BrandTM.
Avoid planting too deep, and wait
for soil temperatures to reach at
least 60 degrees. If sh2 types
cross-pollinate with other sweet
corn types, eating quality is lost.
So, isolation is required by at least
250 feet from su, se, synergistic,
field corn, and popcorn. You do not
have to isolate sh2 types from
Augmented Shrunkens.
Like sh2 cultivars, Augmented
Shrunken types should not be
planted too deep, and soil
temperatures should reach at least
60 degrees before planting.
Augmented shrunken types need to
be isolated from su, se, synergistic,
field corn, and popcorn.
Opportunities for Learning
G ATEWAY G REEN INDUSTRY
CONFERENCE
The Gateway Green Industry
Conference and Trade Show is set
for February 16 and 17 at the
Gateway Center in Collinsville.
The conference offers sessions in
these categories: arborist, golf,
sports turf, landscaping, bedding
plants, parks and recreation, and a
miscellaneous category that features
diseases of roses, wet weather pests
of turf, and managing your time and
your bottom line.
The conference is designed for
those who work in landscaping,
lawn care, nursery, garden center,
golf course, or any other groundsrelated industry. It’s also an
excellent conference for
Master Gardeners.
The Newest in Color, presented by
Allan Armitage, University of
Georgia, will be the keynote on
Tuesday. On Wednesday, Jeff Iles,
Iowa State University, will talk
about landscape problems that can
and should be prevented.
The conference also includes a
commercial trade show.
Registration for the two-day
program is $95, or $75 for one day
if registration is completed by
February 5. After this date, and at
the door, registration is higher.
Certified Master Gardeners can
attend for the discount rate of
$30 (one day) or $45 (two days).
To see the complete program and to
register online, log on to
madisonstclair.extension.uiuc.edu.
You can also obtain the
conference brochure from your
local Extension office.
The Master Gardener—3
TREE F RUIT SCHOOL
VEGETABLE SCHOOL
The Commercial Tree Fruit School
focuses on apple and peach
production. The school is offered at
two locations —on February 2 at the
Mt. Vernon Holiday Inn, and on
February 3 at the First Presbyterian
Church Hall in Hardin. Registration
starts at 8 A.M. and the program runs
from 8:25 to 3:55 P .M.
The Commercial Vegetable School
is set for February 10 at the
Mt. Vernon Holiday Inn.
Topics include a grower’s
evaluation of peach cultivars,
proven cultural practices for apples,
managing fungicide resistance,
GAP readiness, insecticide updates
for peaches and apples, degree day
models for insect pests, and more.
For the Mt. Vernon school, advance
registration by January 29 is
$20 per farm, with lunch on your
own. Late and at-door registration is
$30 per farm.
For the Hardin school, registration
by January 29 is $20 per person,
which includes an on-site lunch.
Late and at-door registration is
$30 per person.
Registration starts at 8 A.M., and the
program runs from 8:25 to 4 P .M.
Topics include cucurbit disease,
vegetable fertility, mistakes in hightunnel production, GAP readiness,
safer vegetable marketing, grafting
vegetables, pumpkin varieties, and
sweet corn insect control.
Registration by February 5 is
$30 per farm. Late and at-door
registration is $40.
The fee includes the Midwest
Vegetable Production Guide for
Commercial Growers 2010.
For details, visit this website:
http://web.extension.uiuc.edu/
edwardsvillecenter/.
For details, log on to
http://web.extension.uiuc.edu/
edwardsvillecenter/.
MASTER G ARDENER TRAINING S TARTS THIS MONTH
Remember that, as a current Master Gardener, you are welcome
to attend any sessions of the 2010 Master Gardener training that
interest you. This is an excellent chance for an update on topics.
The Master Gardener training will be held on Thursdays in Vienna,
January 21 through April 9. On Wednesdays, the training is
offered in Effingham, from January 20 through April 7. For the
southwest area, the training is on Tuesdays, January 5 through April
20, and rotates between Edwardsville, Belleville, and Waterloo. At
all locations, classes run from 9 A.M . to 3:30 P.M.
Contact the Extension office for a complete schedule.
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: Martha Smith, Elizabeth
Wahle, Jennifer Schultz Nelson,
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.
Rex Begonia Offers Gorgeous Foliage
Variegated plants generally
need far less light than most
flowering plants do. And, one group
of plants with an incredible level of
diversity in foliage color and pattern
is the
Rex Begonia. These plants are
grown specifically for their foliage.
They do flower, but the flowers are
usually not very showy.
Although they lack showy
flowers, Rex Begonias offer
gorgeous foliage. The leaves may
be bumpy or smooth, streaked with
white, pink, yellow, or purple, and
the leaves come in many shapes.
Rex Begonias need humidity.
Crispy brown edges on the leaves
are usually a sign that the humidity
is too low. Generally, Rex Begonias
need in excess of 50 percent relative
humidity, which can be hard to
achieve in homes during the winter.
One way to increase humidity
is by placing your begonias on trays
filled with water and pebbles,
without the water actually touching
the pots. Running a humidifier in
the room is another option.
While they thrive in high
humidity, begonias will not tolerate
wetness. If kept wet too long, they
will probably succumb to mildew
and botrytis, which are moisturerelated fungal diseases that turn
your plant into a mushy rotten mess.
To counteract overwatering,
make sure there is good air
circulation around your plants and
use a potting mix with excellent
drainage. Also, avoid “calendar
watering”—watering on a strict
schedule. Inspect plants and assess
whether they need water, regardless
of what the calendar says.
In general, the top of a Rex
Begonia’s soil should just begin to
dry out before watering again.
Rex Begonias need bright,
indirect light. Direct, hot sunlight
will bleach out their brilliant colors.
Morning or late afternoon filtered
sunlight is acceptable.
Rex Begonias also require
temperatures higher than 60
degrees. They thrive at temperatures
around 70 degrees during the day.
These plants are relatively slow
growers that benefit from using a
balanced fertilizer during the
growing season to maximize color
development in the foliage.
With a little effort, Rex
Begonias will brighten even the
dreariest winter day.