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  • From: Neil Bertrando <neilbertrando@gmail.com>
  • To: permaculture <permaculture@lists.ibiblio.org>
  • Subject: [permaculture] mulch and arthropod herbivore habitat
  • Date: Mon, 18 Jul 2011 13:56:45 -0700

HI all,

Have people dealt with the situation where mulching areas in Zone I and II
leads to excessive pest problems which eat all seedling starts?

We consistently have this problem here in Reno, NV in the high desert, and
have stopped mulching our gardens for the most part for this reason.
Sometimes we do light straw mulches, but we are straying away from deep
mulch beds and no-till regimes.

Here's my assessment of the problem, and perhaps other people have dealt
successfully with this issue.

pest populations increased by deep mulching

- european earwigs
http://entnemdept.ufl.edu/creatures/veg/european_earwig.htm
- sowbugs/rollypolly isopods
http://www.ces.ncsu.edu/depts/ent/notes/O&T/flowers/note11/note11.html


most info I have read does not include these as major crop pests however
through direct observation we have seen them here to be the culprits.

they prevent seedling establishment eating them at the cotyledon stage, and
even eat small trees when planted in an area with dense populations.

Strategies tried:

- traps:soap and sugar, soy sauce and oil, beer, etc. work for
established plants but don't drastically diminish populations and are time
consuming
- diatomaceous earth: also works for established plants when applied at
night to feeding insects, time consuming, needs reapplication consistently
- chicken food: grazing with chickens in late fall and early spring.
chickens eat them happily and we tried to get them in when small veggies
are not growing and at key stages in the insect life cycle to minimize
reproduction. still not effective at diminishing populations to a level
where we can get seedlings established.
- transplanting in established seedlings: still get heavily eaten
- get plants established before the populations boom as weather warms:
works fairly well, but not a strategy for warm season crops and makes fall
cropping difficult.
- raised beds: works for a while until populations get established (1-2
years) in the beds and structural material

so now we've stopped mulching heavily in Zone I and use mostly on-site
generated mulch in Zone II, using only a scattered straw mulch to decrease
wind and sun evaporation and a focus on row covers instead of mulch to
achieve this function. any off-site woody mulch needs to be composted
through hot compost piles before being applied to the Zone I and II gardens.
and this seems to work well since there is no habitat for them in the
garden.

My conclusion is that sheet mulching (and deep mulching) is not an effective
strategy in our climate context for Zones I and II. Has anyone else found
this to be the case? or are we just applying the technique incorrectly?

some thoughts are

- that N is being tied up in the mulch, and the insects are relying upon
seedlings to fulfill this need, although this occurs in mulches with
relatively high manure content as well.
- natural foods and predators of these organisms are not in balance and
take years to come into balance (or are not present at all in our climate?)
- mulch increases the humidity in summer and decreases the cold in winter
which allows populations to grow rapidly out of balance with plants.
- there is some other factor that is causing plants to lack hardiness and
become attractive to these organisms

This situation has been very disheartening to many beginning Permaculture
gardeners who read about the wonderful benefits of mulch and have their
veggie gardens decimated. Any thought and suggestions would be very helpful
for gardeners in our region.

Thanks,
Neil




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