Download The Master Gardener Time for Crabgrass Control

The Master Gardener
Volume 16, Issue 3
March 2009
Time for Crabgrass Control
Pre-emergence weed killers for crabgrass control are applied to lawns in
the early spring. The herbicide forms a chemical barrier or blanket at the
soil surface, which prevents the seeds that have absorbed the weed killer
from emerging.
Crabgrass control needs to be specifically timed. The annual seeds don’t
germinate unless the soil temperature is around 55 to 60 degrees for seven
to 10 consecutive days. In southern Illinois, this usually occurs sometime
between March 15 and April 1.
This is the time to apply the first crabgrass application. Look for a
“pre-emergent” crabgrass weed killer that contains no fertilizer. The
reason is that fertilizer stimulates green shoot growth at the expense of
root growth. At this time of year, our goal is to promote root development
so that we get a vigorous, dense turf, which helps prevent crabgrass
infestation and helps the turf survive the heat and drought of summer.
Wet conditions caused by spring rains may delay crabgrass seed germination until May or early June. Dry conditions can cause the same thing.
Most crabgrass preventers have a residual of six weeks, so another
application in mid-May helps control the late-germinating crabgrasses, as
well as other weed seeds. A fertilizer application can occur at this time.
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
While pre-packaged “step” programs can be beneficial, remember that
they are based on the “average” lawn. Each lawn is different, and a
packaged program might not be the best bet for any given specific lawn.
Some good lawn management practices will help control crabgrass. Weed
seeds need light to germinate. A thick, lush turf prevents the weed seeds
from getting enough light. So, avoid mowing the lawn less than 2 inches
high because a short turf allows more light to reach the weed seed.
Lawn seeding is another consideration. Most pre-emergent weed killers
can’t distinguish between weed seeds and “good” grasses such as fescue
and bluegrass. For that reason, it’s better to seed a lawn in the early fall
when crabgrass won’t be germinating.
For more tips, check out the Spring Lawn Care fact sheet at our
SI Gardening website, http://web.extension.uiuc.edu/regions/hort.
In this Issue
Perennial Plant of the
Year Announced
Starting Seeds Indoors
Controlling Disease on
Flowering Crabapples
Perennial Plant of the Year Announced
The Perennial Plant Association
(PPA) 2009 Perennial Plant of the
year is Hakonechloa macra
‘Aureola’—commonly called
Golden Hakone Grass.
PPA members annually submit
nominations, and the top five are
sent out for the membership to
make the final decision. Growers,
retailers, designers, and independent
gardeners make up the diverse
mix of membership from all across
North America and Europe. To be
selected as the perennial plant of the
year is to be chosen from a large
cross section of the green industry.
Golden Hakone Grass grows 12 to
18 inches tall and 18 to 24 inches
wide with an arching form that
resembles a cascading miniature
bamboo. Individual blades are
½ inch wide and bright yellow with
thin green stripes. Cool autumn
weather brings out shades of pink
and red in the foliage. Mainly
grown for its golden foliage,
Hakonechloa produces tiny flower
spikes August through September.
Hardy to Zones 5 to 9, it should do
well in most Illinois gardens. The
exception would be far northern
Zone 4 areas. Hakone grows best in
moist, humus-rich, well-drained
soils. If you have poorly drained
soil, heavy clay soil or very dry soil,
this grass will not perform well.
Amend the soil with organic matter
or aged manures to improve the
conditions for Golden Hakone
Grass to survive.
Partial shade is the preferred
location, though more sun brings
out the golden foliage color. Deep
shade often results in foliage that is
more green than golden.
Golden Hakone Grass does spread
by stolons but so slowly that it is
not a threat to take over a garden. In
fact, many gardeners wish for a
faster pace! Due to this, the plants
don’t need to be divided for several
years. When division is required, do
so in early spring as new growth is
developing. Another plus is that this
shade-tolerant grass has few insect
or disease problems and is not
favored by deer.
Hakonechloa is a great hosta
companion. The golden foliage
contrasts well with blue-foliaged
hostas and accents those with
golden centers or edges. Other
companion plants to consider are
astilbe, tiarellas, heucheras (Coral
bells), bleeding heart, and lady’s
mantle. You can also use it in a
container and let it cascade over the
edge like a waterfall.
Hakonechloa macra ‘Aureola’
brightens a shady spot, complements purple, red or blue foliage
companion plants, and offers an
oriental feel to a garden. The foliage
also catches the breeze, offering
motion to your landscape.
Go for the gold this year and try
Golden Hakone Grass.
From Page 4
Homeowners interested in treating
susceptible crabapples can consider
topical treatments to the foliage
along with the cultural practice of
sanitation each fall. Treatments will
need to be applied several times
during the early spring when the
spores are in the air and while the
weather remains cool and wet.
These treatments must start as the
leaves are expanding out of the buds
and continue until the leaves are
The Master Gardener—2
nearly full grown or until about
three-fourths of the flower petals
have fallen.
Once warmer, drier weather arrives,
most of the spores cannot survive
the time it takes to float to the leaf
and infect it. If homeowners are
also growing fruit trees in their
yard, those will need to be sprayed
for Apple Scab throughout the
season to protect developing fruit.
Instruct homeowners to look for
Apple Scab on the label of the
fungicide sprays they are using.
Most multi-purpose fruit tree sprays
contain the right material.
Remember that as the tree develops
more foliage, more spray per tree
will be needed, and complete
coverage of each leaf is necessary.
Starting Seeds Indoors
March is an ideal month to sow seeds
indoors for your own transplants.
Starting your own seeds holds several
advantages over purchasing plants.
First, you can choose exactly what
plants or cultivars to sow. You may
want a certain type or color that is
unavailable locally.
Sowing seeds is also an inexpensive
means of obtaining a large quantity
of plants. The cost of raising
100 marigolds is much less than
buying them.
Starting your own seeds also lets you
get a jump on gardening by having
plants ready when you want to transplant. Most plants can be set outside
six to eight weeks after sowing.
However, all the advantages
disappear if seeds aren’t properly
sown and maintained.
Seeding success can be attributed
to four factors: quality seeding
medium, moisture, temperature,
and light.
Most homeowners use houseplant
soil for starting seeds. Packaged
mixes are satisfactory as long as the
material is sterilized.
If the mix isn’t sterilized or if the
package has been opened, sterilize the
soil by placing the moistened soil in a
metal pan for 30 minutes in a 200°F
oven. An old meat thermometer can
be used and should register between
130 and 140 degrees.
Cooking soil smells, so you may want
to place the soil in a roasting bag, or
make sure the windows are open.
Houseplant soil should be loose and
well-drained. If it isn’t, add peat
The Master Gardener—3
moss, vermiculite, or perlite. Garden
soil is generally too heavy to use as
an indoor seed medium unless it is
modified with equal parts of peat
moss and vermiculite.
Some gardeners report success using
individual peat pots for starting
seeds. A common type is the Jiffy-7
pellet, which expands when wet.
Make sure you don’t allow the pots to
dry out. Likewise, avoid setting the
Jiffy-7 pots in water.
Seeds need uniform moisture to
germinate and grow. Part of the
germination process involves
absorbing water. It’s important the
water supply is present during the
entire germination process.
But, too much water can deplete the
seeding medium of needed
oxygen. Water only to maintain a
moist soil, never soggy or saturated.
Once seeds have germinated and are
established, you might be able to
reduce the amount of water
needed. Do so carefully to avoid
wilting the seedlings. Once wilted,
most seedlings never recover.
It’s a toss-up by professional
horticulturists which is more important: temperature or light. Both are
related and dependent on the other.
Soil temperature is crucial for seed
germination. The ideal temperature is
75°F. However, the air temperature
for seeding should be 65 degrees.
Greenhouses can supply bottom heat
by placing the seeding flats on steam
pipes. For home germination, heating
cables are available at most garden
centers, greenhouses, and nurseries.
You can also set the seed flat on top
of the refrigerator to get some of the
bottom heat needed. Just don’t forget
the flat is up there.
Once seeds have germinated, keep
the air temperature on the cool
side. In fact, lower temperatures
usually produce a shorter, stockier,
and healthier transplant. Night
temperatures can be as low as
55 degrees. Day temperatures should
not be above 65 degrees.
Light is important for growth.
Seedlings need at least 14 hours of
bright light each day. Setting the
plants in a south window helps, but
temperatures may be too warm and
produce vigorous but spindly growth.
Plants can be placed under lights.
Make sure plants are close enough to
receive the maximum benefit, but far
enough away to prevent burning.
Plants should be placed no closer
than 6 inches and no farther than
12 inches from fluorescent bulbs.
If using incandescent types, keep
plants 12 inches away, but closer than
24 inches.
If seedlings are tall and lanky with a
large distance between sets of leaves,
the cause is usually temperatures
being too warm or not enough light.
Avoid fertilizing transplants indoors
unless growing conditions are ideal.
It is better to wait until you transplant
the seedlings
outdoors.
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, Martha Smith,
Richard Hentschel
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.
Controlling Fungal Disease on Flowering Crabapple Trees
Every year when the weather has
been cool and wet in the spring,
homeowners find their flowering
crabapples with olive green spots on
the leaves.
Worse than that, by mid-summer
nearly all the leaves have fallen,
leaving just a few at the ends of
each branch for the remainder of the
summer. What remains is a tree that
will be stressed and lacking in the
production of nutrients since the
leaves are the “food factory” for the
tree—plus, the flowering crabapple
will not look very good.
This is a fungal disease called
Apple Scab—the same foliar
disease commercial and home
orchardists face on a number of
apple varieties.
Apple Scab overwinters on the
decaying leaves laying underneath
your crabapple and surrounding
area. When the early spring wet
weather arrives, the disease
becomes active and releases spores
into the air. These spores then infect
the newly developing leaves on the
tree. Apple scab can also attack the
crabapple fruits themselves, but
since we do not eat those fruits, it is
the foliage loss that bothers us most.
So, what advice can you give when
the calls start coming in?
Start by raking up the leaves and
crabapples for disposal—remove
the source and you lessen next
year’s outbreak. Homeowners will
not be entirely successful just raking up the old leaves and crabapples
since the spore is airborne and can
float into the yard from anywhere in
the neighborhood. But, they will
have a lot less disease.
Pruning a crabapple for more
sunlight penetration and air
movement will allow the foliage to
dry sooner, limiting the time when
fungal spore can penetrate the leaf
and infection takes place.
If planting a new flowering
crabapple, there are many new
disease-resistant cultivars on the
market. Buyers should ask about
Apple Scab resistance before
making their selection.
Today, flowering crabapples come
in a variety of plant shapes,
mature plant sizes, levels of disease
resistance, and flower color.
Continued on Page 2