MAY
2006
By
Rosie Lerner
Consumer Horticulture Specialist
Purdue University
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Q. I am hoping that you can give me some advice on my yard. I think I
may have a fungus. Nothing grows very well. Last year I planted bell peppers
and tomatoes, and they were inedible. They were full of white veins. All
of my trees have small holes in the leaves. And my grass has small pale
patches all over the yard. My income is limited. Can you suggest a treatment
that is not too expensive?
A. Well, the good news is that there is no one organism that would attack
all of the different types of plants that you've mentioned. Most diseases
and insect pests are what is referred to as "host specific,"
meaning they attack a particular, or sometimes a few different, species.
When that many different plants are affected, it's more likely to be something
related to environmental factors, such as weather, poor soil conditions,
etc., or management, such as improper watering, fertilizing, etc. And,
there is no one solution to all of these various problems. You must first
diagnose the problems before any recommendations for treatments can be
made.
For assistance in diagnosing these various problems, contact the Purdue
Extension office in your county and take them some samples of the various
affected plants. You can look up the contact information for your county
online at http://www.ces.purdue.edu/counties.htm.
Q. I have two forsythia bushes that I started from cuttings. They are
about 3 years old and are growing quite well. They are nice and bushy,
but they have never bloomed. The bush that I got the cutting from blooms
every year. Do you have any ideas as to what could be wrong? I would appreciate
any advice.
A. Flowering is the reproductive phase of plant growth, and so plants
need to reach a certain degree of maturity to be able to flower. While
there is no one specific age at which all woody plants become mature enough
to flower, 3 years is pretty young for most trees and shrubs. Other reasons
for lack of flowering can include insufficient light (too shady), excessive
nitrogen (promotes excess leaf growth and delays maturity) and, in the
case of forsythia, the flower buds are often damaged by late spring frosts.
If these cuttings are near the parent plants and exposed to all the same
conditions, then I would assume they just need a few more years to reach
maturity.
Q. I am surrounded by corn and wheat fields. I seem to have more weeds
in my garden than they do in their fields. They just got through spraying
for something. I have pretty blue weeds taking over the garden now. Can
I put "preen" all over to cut the weeds? I want to plant potatoes,
peppers, cukes, squash, tomatoes, carrots and beans.
A. Ah, beauty is in the eye of the beholder! Those “pretty”
blue weeds are likely either henbit or the closely related purple deadnettle.
They both have similar purplish-pink flowers and square stems, but the
purple deadnettle has a spade-shaped, stalked leaf, and the henbit has
more of a scalloped-shaped, stalkless leaf (leaves clasp the stem). They
are both winter annuals, meaning their seeds germinate in the fall, flower
and produce their seed in early spring. By the time you see them flowering
in the spring, the best means of control is manually by hand pulling,
hoeing or tilling.
Preen® contains trifluralin as the active ingredient, which is ONLY
effective at preventing some weeds (mostly annual grasses and some annual
broadleaves) from germinating. It will not provide any control once the
weeds are already growing.
For trifluralin to be effective against either of these two weed species,
it would have to be applied in the fall before their seed germinates.
Trifluralin is labeled for use on many but not all vegetable crops, and
the appropriate time for application depends on the specific crop, so
it can be tricky to use in a small garden. As always, be sure to read
the label before you apply.
Q. I have a problem with my muskmelon. The problem arrives when the vines
are fully grown and the fruit is in various stages of development. Overnight,
the vines wilt and hopes for a melon are gone. Can you offer a solution?
A. The most likely culprit is bacterial wilt, a disease that clogs up
the water conducting tubes that in turn causes irreversible wilting. The
bacteria is transmitted to the plant by cucumber beetles (both striped
and spotted types) as they feed on the foliage. Once the plant is infected
with the bacteria, there is no cure. Infected plants should be removed.
There are a few cultivars of cucumbers that are resistant to bacterial
wilt but none yet in melons. So the only hope is to prevent the cucumber
beetles from feeding.
Early-season use of floating row covers can help reduce beetle feeding,
but covers will need to be removed when plants are blooming to allow bees
to pollinate. Yellow sticky-cup traps can reduce beetle feeding, if placed
around the borders or about every 20 feet within the row and replaced
as needed when they are no longer sticky.
A promising new product called "Surround At Home®" contains
fine kaolin clay particles as the active ingredient. Neem oil is also
labeled for beetle control on melons. More traditional insecticides that
are labeled for cucumber beetle control on melons include carbaryl (very
toxic to bees) and methoxychlor (less toxic to bees). Always read and
follow label directions before applying.
Q. I have a 10-year-old snowball bush that was taken from a cutting of
a cutting from my grandmother's dating back probably 100 years. Last year,
some of the sections growing up from the ground wilted and died. This
year, when one of the three remaining sections failed to bloom (and the
other two looked like Charlie Brown's Christmas tree), I investigated
and found a white caterpillar hidden in little sawdust sacks burrowing
in grooves up inside the bark around the entire base of the three sections.
I cut the dead section out and I tried to pull the little buggers from
the two surviving sections, but the softened bark came off with them.
What kind of bug is this, and is there anything I can do to save this
bush, or is it doomed? Is there anyway to get a cutting from this plant
to start a new one?
A. Sounds like one of the viburnum borers, which as an adult is a clearwing
moth that emerges from the tunneling larvae in midsummer. Affected plants
are, at best, weakened and, in serious cases, can dieback as you've experienced.
Plants that are injured and/or stressed are most susceptible to attack
by borers. Avoid pruning plants during the growing season and keep mowers
and weed whips well away from the stems. Remove all affected stems, preferably
during the dormant season; however, now is better than midsummer. Plants
can be sprayed with either permethrin or bifenthrin (Ortho) in midsummer,
just after the adults emerge.
As insurance, in case the plants do not recover, take cuttings anytime
in late spring or early summer, selecting the healthiest-looking twigs.
Take a 6-inch or so length of the stem tip, remove the lower pair of leaves
and dip the cut end of the stem in rooting hormone. Insert the cuttings
into moistened potting soil or vermiculite, and keep the humidity high
around the cuttings with a ventilated plastic bag. Gently lift the cuttings
out of the mix in 3-4 weeks to check on rooting status. Once the new roots
are an inch or so long, you can either transplant them in a protected
outdoor location, or repot and raise them in containers until early fall.
5-4-06
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