Pulling weeks around the new batch of Cucumbers and Zucchini this morning i
am seeing squash bugs again. I looked at the leaves and do not see any egg
s (ok not every leaf but a most of them) even on the ones that have holes e
aten in them. Have they hatched or have they not laid them yet. The plants
are about 3 weeks or so old. The cucumbers are "trailing" with flowers and
the zucchini have male flowers. I used Seven dust at the base of the plants
and around them with a very light dusting on the leaves. Is there anything
else I can do? I don't see any damage at the base of the plant (going into
Why are you a gardener, to facilitate your consumption of toxic
compounds? Sevin is a nerve poison. Of more concern is that there are no
long term exposure studies for humans. No studies of how a young,
developing child's exposure may differ from that of an adult. It isn't
so much eating the sprayed produce (after the waiting period has elapsed
either (although it's a concern), it's the repeated incidental exposure
from skin contact and inhalation while mixing and applying.
However, of even more concern to *me* is the toxicity to things I don't
want dead. Pretty much every university extension service I have read
agrees those who regularly use broad spectrum insecticides in their
gardens end up with more pest problems than those who do not. The logic
is straightforward. All insects die, not just the pest. Pest bugs
reproduce faster than bugs which eat them so as soon as the pesticide
wears off the pest bugs are now able to enter the garden and reproduce
with reduced predation.
Before too long one is spraying often enough that they exceed the
maximum number of applications per crop the label indicates or they
start mixing the pesticide at a stronger dose than the label allows.
Given the availability of more selective pesticides in many cases or
broad spectrum pesticides with a shorter lifespan in the environment I
guess I don't get why one would go for something like Sevin as a garden
The label on the Sevin I've seen has a 2 week wait before eating many
plants such as lettuce and other leafy edibles.
The wait is 1 day for asparagus, 2 for sweet corn ears, 3 for cucurbits
and fruiting plants, 7 days for most root crops and small fruiting
plants (berries), 14 days for leafy veggies etc.
Additionally the label indicates not to apply more than a certain number
of times per crop (varies on the crop) over the entire growing period,
something easily missed by those not reading the label instructions very
Sevin is hardly benign, with all due respect. It is one of THE most
toxic pesticides for bees and other hymenopterans. It is also one of the
most deadly chemicals to use around earthworms. To say nothing about the
effects on mammals. It's a cholinesterase inhibitor!
Carbaryl (Sevin) is a widely used insecticide with several
trade names. It is effective on beetles and some caterpillars
but does not kill aphids. Carbaryl is persistent on plants for
3-4 days, but may cause outbreaks of aphids and spider
mites by killing natural enemies.
Many insecticides kill bees. Some cannot be applied
safely at any time when plants are in bloom, while
others should be applied only in the early morning
or late evening when bees are not foraging for nectar
and pollen. Avoid spraying carbaryl (Sevin) on plants
that are surrounded by blooming flowers or weeds.
Mow lawns next to garden areas to remove clover
blossoms before applying any material hazardous to
bees. This is a simple step and one you should always
follow. In all cases, when plants in the infested area
are in bloom, select the material least hazardous to
bees. Avoid using dusts whenever possible. Sprays are
preferred for bee safety. For additional information
on this subject, refer to PNW0591,
How to Reduce Bee Poisoning from Pesticides , available
from Extension offices and http://pubs.wsu.edu
Squash bugs do not eat holes in leaves. They are true "bugs": They
have piercing, sucking mouth parts.
Carbaryl ("Sevin", a trade name) should be used only before
enflorescence or, at the very latest, before pistillate flowers appear.
"Female" flowers are easy to spot before they open because each has a
nascent pepo clearly visible at the base of the bud. You don't want to
eat carbaryl, even at the supposed "safe" 2% concentration.
What kind of damage are you looking for? From
The wilting is similar to the symptoms of nematode infestation. However,
the plants will not "perk up" overnight.
If you're seeing small holes and frass in/on the vines near the
root crowns, what you have are squash vine borers, a different sort of
As an expedient, clear all mulch from under the vines and place
flat boards or something similar around the bases of the vines to
attract the bugs and their nymphs so that you can murder them in
whatever manner you find most rewarding. The key to control, such as it
is, is an early start: At the first breakout of the season, diligently
search the undersides of leaves for eggs and roust out nymphs before
they become reproductive.
I'm neither a rabid "organic" gardener nor an evangelist but,
personally, I'd forgo planting curcurbits if the only insect controls
were carbaryl and permethrin (a synthetic "pyrethroid", _not_ the same
One nearly free method that you might try is to sow buckwheat far
enough ahead of the squash as to be well enough established that the
squash vines won't shade it out. Buckwheat attracts a native tachinid
fly, which parasitizes squash bugs. Not exactly a quick clean kill but
If your IP connection will allow, I highly recommend that you
download, print and study the PDF document found here:
and, if squash and cucumbers mean that much to you, decide for yourself
which combination of controls that it outlines might be appropriate for
your garden and, above all _keep a journal_ to document results.
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