Coastal Gardener - October 28, 2003
COASTAL GARDENER
Franklin Laemmlen
Q:
Part of our yard is enclosed by a wrought iron fence. This fence is constantly
entangled by masses of spider webs. Is there anything I can do to reduce or
eliminate this nuisance?
A:
I mentioned in a Coastal Gardener column a few months ago that the Central
Coast is a “spidery” place. Apparently, the mild temperatures and humidity levels
are ideal for spiders as well as other living things. Now if you add to this a
wrought iron fence, you really have perfect habitat for web-spinning spiders to set
up house. During the fall months web spinners are especially active as female
spiders try to catch enough food to mature a large batch of eggs, which will allow
survival through the winter and perpetuate the species for another year.
The ideal solution to your problem would be to get rid of the wrought iron fence
and replace it with a regular fence that does not have so many holes in it. Another
option is to wash the fence down with high pressure water once or twice a week.
Water, however, does not kill spiders, so they will be back spinning their webs as
soon as the “rain” stops. Remember the “itsy, bitsy spider.”
A third option is to use chemicals. Insecticidal soap, horticultural oils, diazinon,
pyrethroids, chlorpyrifos are all contact materials that are lethal to spiders.
Contact is the key word. Whatever you use has to get on the spider in order to kill
it. Therefore, you should use a good sprayer and apply the proper dosage of
chemical plus a few drops of a wetting agent (detergent). The wetting agent is
added so the webbing will get wet. You may have to spray the fence several times
at about seven- to ten-day intervals to reduce the spider population down to
acceptable levels. Remember that any chemical you use will only give you
temporary control. Young, newly hatched spiders travel on little parachutes like
dust in the wind. So any location that is treated to rid it of spiders will be quickly
recolonized by new immigrants. And there are few web-spinning spiders that can
resist a wrought iron fence.
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Coastal Gardener - October 28, 2003
Q:
My silk tree (Mimosa sp.) is covered with tiny puffs of cotton. The leaves are
turning yellow and dropping prematurely. Are the cotton puffs and the yellow
leaves related? Is there a remedy?
A:
The cotton puffs are actually adult mealybugs, and an examination of the
specimen you submitted indicates that the adults are having babies. Yes, the puffs
and the yellow leaves are related. Mealybugs suck sap from the plant, and when
enough of them are present, leaf yellowing and leaf drop is an initial symptom in
the decline of the plant. Mealybugs can be controlled with insecticidal soap and/or
horticultural oil. Whichever you use, one or both, contact is essential to good
control. All plant surfaces should be covered with spray. Also spray the base of
the plant well as some mealybugs may be feeding on roots and the stem just
below the soil line.
Also pay attention to ant control. Ants shepherd mealybugs and will quickly
reintroduce the mealybugs to your plant if not controlled. If the plant has a single
stem, a band of “Tanglefoot” on the trunk will be useful in keeping the ants at
bay.
Send your landscape and garden questions to: The Coastal Gardener, 624-A
West Foster Road, Santa Maria, CA 93455.
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