| Beverly Shaw
Question and Answer
Q. I have a weed in my garden that I can't get rid of. It lies close
to the ground and spreads. It has small green leaves that are thick and
feel like rubber. Is there anything you can tell me to help me get rid
of it? Thank you. - Sheila Denton, via e-mail
A. It could be a number of weeds but sounds most like purslane. Purslane
thrives in hot, dry weather. The green, rubbery leaves are 1/2-1 1/2 inches
long on thick, reddish- green stems. It sometimes bears yellow flowers,
and the seeds are borne in a small pod with a top that comes off like
a lid on a cookie jar. If this sounds like the weed you have, read on.
If not, take a sample to the Purdue Extension office in your county for
Chemically, you can treat with glyphosate (sold as Round-up or Kleen-up)
but you must use care. Any green plant material sprayed with glyphosate
is killed, so spraying with this non- selective herbicide is not recommended
anywhere near desired plants, like vegetables or flowers. If the purslane
is growing in your turf, you could use a broadleaf herbicide.
In this case, however, the best method is probably pulling by hand. Since
purslane roots wherever it touches the ground, any plants that are pulled
or hoed must be completely removed from the garden, or they'll root again!
Instead of reducing the population, hoeing can increase it. A layer of
mulch at least 3 inches thick will help reduce weed populations from garden
beds. Purslane is a warm-season annual, so weed removal, mulch and a pre-emergent
herbicide can prevent the same problem from reoccurring next year. If
you're directly seeding new vegetables or flowers in the garden, do NOT
use a pre-emergent herbicide, as it will keep those plants from germinating.
On the up side, purslane is an excellent crunchy salad plant. Check out
for a host of recipes for stems and leaves, including Purslane Con Queso,
Pickled Purslane and Ham and Purslane on Rye! Another Web site with loads
of information is http://www.hort.purdue.edu/newcrop/1492/neglected.html#Purs
lane. Here, you'll find ways to increase production (if you just can't
get enough of it) and interesting purslane facts.
Q. For no apparent reason, the leaves on my mountainash are turning yellow,
drying and falling off the tree. Is there any treatment for this condition?
A. There are several species of mountainash but all are of the genus
Sorbus and all are susceptible to a great number of diseases and insects.
Fireblight is common; crown gall, canker, leaf rusts, scab, aphids, pear
leaf blister mite, Japanese leafhopper, roundheaded borer, mountainash
sawfly and scales and borers all find mountainash to their liking. To
accurately diagnose the problem with your tree, you'll need to inspect
it more closely. Look for anything unusual on the leaves, branches and
trunk and take samples to your Purdue Extension office in your county.
In general, these are not highly recommended landscape plants, due to
the potential problems and short life expectancy. This is a shame because
the highly colorful fruiting in the fall is spectacular. The best line
of defense is a vigorously growing tree given plenty of fertilizer and
water during the growing season. The Korean mountainash (Sorbus alnifolia)
is least susceptible to borers and has the most aesthetic fruiting effect.
This tree should not be planted in stressful situations (for example,
as a street tree). It prefers a cool, moist climate that is difficult
to replicate in Indiana.
Q. For the first time in 50 years of gardening, I have whiteflies. I
have tried everything. My cucumbers and tomato vines all died so I pulled
them out. I notice they are spreading to my roses, and I'm fighting to
keep them out of my asparagus and rhubarb. Please advise what to do other
than never to buy my plants at that nursery again. - Audrey Gilland Fort
A. First, the good news. Whiteflies are basically tropical insects that
will be killed off by our cold Indiana winters. Be careful not to overwinter
any by bringing infested plants into the house this fall.
The bad news is that they have five stages of development, and each stage
has a varying susceptibility to insecticides. Since all life stages can
be present at one time, it's impossible to identify the stage and apply
the appropriate insecticide. Treat with diazinon, malathion, orthene or
insecticidal soap, but make sure you follow the directions concerning
reapplication, so you control new whiteflies as they hatch. Most insecticides
require at least three applications at intervals of four to six days.
Since this is on edible crops, make sure the product is labeled for use
on that crop, observe harvest restrictions and read and follow all other
You can also purchase sticky, yellow traps and hang them in the infested
plants. The whiteflies are attracted to the yellow color and once they
land, they can't take off again.
Finally, it's unlikely that the whitefly actually is what is killing
your plants. Although whiteflies do suck sap out of the plants, their
main threat is in the possible transmission of virus, and viruses tend
to be more host- specific. With so many different sorts of crops dying,
it isn't likely that a virus from the whiteflies is the culprit. Put on
your detective hat and search for cultural problems, including watering
practices, soil conditions, etc. I would still try to get the whiteflies
under control, however.