From the HBD Archive
From: dplatt@ntg.com (Dave Platt)
Subject: re: bugs are eating my hop plants
Date: 1992-06-23 17:20:05 GMT

> Some pests are eating the leaves off of my hop plants! I am looking
> for some friendly pesticides or remedy, as one of the plants is almost
> gone. I'll check the WAIS HBD archive for stuff, but I am looking for
> something like a cigar nicotine extraction method to put on the plants,
> or something equally innocuous. I have done this before for other
> plants, but want to collect net wisdom before I do anything.

Home-made "tobacco tea" has a number of real disadvantages, and I don't
recommend using it for the following reason:

- Nicotine is one of the most toxic "botanical" insecticides, weight-
for-weight. It's substantially more poisonous than the commonly-
used synthetic organophosphate insecticides such as malathion.
Commercial nicotine sulphate insecticide is quite poisonous (I
believe that it carries a Danger labelling requirement) and has
been the source of a substantial number of accidental poisonings
(as well as being a staple in British murder mysteries).

Although "tobacco tea" is a relatively dilute form of nicotine, it's
not something to be treated casually. If you spray it on your
hop vines, take precautions: wear gloves and a facemask, don't
spray on a windy day, don't overspray, don't get it on your skin,
and wash yourself off afterwards.

- A large percentage of commercial tobacco is infected with tobacco
mosaic virus (TMV). This virus can infect most plants in the nightshade
family, including tomatoes, peppers, potatoes, and certain ornamentals.
It can stunt or kill these plants, and is incurable. Don't use
tobacco tea anywhere around these sorts of plants, and don't use the
same sprayer to spray fertilizer, etc. onto these plants at a later
time (TMV can survive, dormant, for quite some time).

- Well-fermented tobacco tea can stink to high heaven.

Two other botanicals you might want to consider, as alternatives, are
pyrethrum and rotenone. Pyrethrum is a fast-acting contact insecticide
with a fast "knock-down", and is of low overall toxicity to birds and
mammals. Rotenone is a stronger contact/stomach insecticide, but is
more toxic (especially to fish) and should be treated with respect.
These botanicals are sometimes used in combination. They biodegrade within
a few days, and so can be used up to within a day or two of harvest
(check the labels for details).

Another technique which sometimes works, is to lay down a barrier of
some sticky substance (e.g. Tanglefoot) on the plant's stem and on
the supports for the trellis. This isn't always practical - one cannot
always blockade all of the routes by which an insect could climb up
into the plant... but if it's practical in your situation, it can
be an effective way to keep crawling/chewing insects from chomping
your plant. [Won't do diddly if you have a problem with flying insects
such as Japanese beetles].

All of this is relevant _if_ your plants are being eaten by insects.
If they're being chewed up by snails, you'll need to use other methods
(e.g. laying down a metaldehyde-laced bait).

Before spraying anything, I'd recommend catching the guilty parties in the
act, so that you'll know what it is you're fighting. This will give you
the best chance of choosing the right remedy, rather than simply nuking
your future homebrew supplies with chemicals (synthetic or botanical)
chosen at random.

Dave Platt VOICE: (415) 813-8917
Domain: dplatt@ntg.com UUCP: ...netcomsv!ntg!dplatt
USNAIL: New Technologies Group Inc. 2468 Embarcardero Way, Palo Alto CA 94303


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