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The best way to combat slugs
is to understand their lifecycle. Slugs themselves are composed
of a high percentage of water and will begin feeding as soon
as soil temperatures rise above 40 F (5 C), emerging from the
soil or from protected areas. Slugs prefer to forage at night
or on dull days when temperatures drop and the garden is damp.
Their gelatinous eggs, laid in clusters of 40-100, can be found
in the soil, under rocks and even in outdoor pots. Learn to recognize
them!
Cultural Methods of Control
There are many simple things
you can do in the garden to decrease slug damage. Because slugs
are made up of so much water, they are very susceptible to drying
out. In the early spring, cultivate your soil to expose their
eggs to drying air & predators. Try to keep your garden as
dry as you can without damaging your plants. This can be achieved
by using drip irrigation or soaker hoses rather than overhead
sprinklers. In addition, if you mulch your garden, keep the mulch
well back from the base of susceptible plants. Better yet, consider
waiting until temperatures rise above 75 F before you apply your
mulch. Slugs also love warm compost piles so if you can, keep
your pile separated from the rest of your garden.
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Handpicking
Handpicking is an extremely effective
way of riding your garden of hundreds of slugs. For the squeamish,
chopsticks, tongs, or even hatpins can be used to catch the offending
pests. The best time to hunt for slugs is 2 hours after sunset
so take a flashlight. Finish the slugs off in a bucket of soapy
water.
Attract or Repel?
Most gardeners choose either
of these methods to prevent slug damage in their gardens. Attracting
slugs into baits or to trap crops and then discarding them is
a popular system. |
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On the other hand, preventing them
from getting to your prized plants is also important. Here are
the basic principles:
Baits
Slugs are attracted to chemicals
given off by the fermentation process. The most popular bait
has been beer. However, not all beers are created equal.
In 1987, a study at Colorado
State University Entomology Professor Whitney found that Kingsbury
Malt Beverage, Michelob, and Budweiser attracted slugs far better
than other brands.
The range of slug traps is only
a few feet so you need to supply a few throughout your garden.
Never, sink the containers with their rims flush with the soil
level or you run the risk of drowning ground beetles, important
slug controllers. The rims should be 1" above the soil's
surface.
In the last couple of years,
a new product has been released into the market that is receiving
rave reviews from organic gardeners. Baits made from iron phosphate
have been found to decrease slug populations without harming
birds, small pets or humans. Scientists are still not sure exactly
how these elements affect slugs but figure that they inhibit
the slug from feeding anymore. The baits are sold commercially
under the name Sluggo, Es-car-go, and Safer's Slug & Snail
Bait.
Trap crops
Certain plants seem to be favored
by slugs and can be used to divert slugs from your prized plants.
Particularly good trap crops include: green lettuce, cabbage,
calendula, marigolds, comfrey leaves, zinnias and beans.
Barriers
Certain plants will also repel
slugs. Ginger, garlic, mint, chives, red lettuce, red cabbage,
sage, sunflower, fennel, foxglove, mint, chicory & endive
seem to be less prone to slug attack. Plant them around the perimeter
of your garden to keep them from infiltrating.
Aside from diverting slugs to
where you want them, gardeners can also use certain barriers
to keep slugs out of particular spots. A ring of abrasive material
such as eggshells, sand, wood shavings, diatomaceous earth, hair
or ash can be placed around susceptible plants. These materials
do have to be kept dry, however, in order to work. After rains,
top them up again. Cutting the tops and bottoms off of plastic
containers and using them as a cylinder around young seedlings
can construct a more permanent barrier.
One of the most effective barriers,
however, seems to be copper tape, as it works wet or dry. When
slugs and snails make contact with the copper, there is a toxic
reaction, similar to an electric shock, which repels them. The
minimum width for the copper barriers needs to be at least two
inches; slug barriers sold in nurseries are often smaller and
should be doubled or tripled when installed.
Slug Predators
Many natural predators will eat
slugs. Providing a habitat for them will help build their populations
so that you do less work in the long run. Slug predators include:
- Ground beetles - Like to live
under wooden boards during the day.
- Frogs - They prefer damp sites
& a quarter of their diet may comprises slugs.
- Birds - blackbirds and thrushes,
robins, starlings, rooks and crows, jays, ducks, seagulls and
owls will eat slugs
There are a number of tools that
a gardener can use to combat slugs. Handpicking, traps, barriers,
baits, & predators are just a few techniques. So, rather
than shrugging off slug damage as inevitable, choose from the
slug control menu and you'll be surprised by the results. |