While I no longer live on the
Gulf Coast, one particular year there is forever imprinted in my memory. The
snail infestation was so bad each morning I would find dozens upon dozens on
the outside doors and walls of the house, the upper porch, the steps and
handrails of the staircase to the porch, every walkway – even on my car! The
damage being done to the plants in the yard and planters was beyond anything I
had ever seen. Gardening has its challenges and one of those is combating
snails and slugs!
If the spring of 2016 is anything
like the spring of 2015 with its frequent periods of rain every week, we will
see a population explosion of snails and slugs; they absolutely thrive in moist,
humid environments like those of the Texas Gulf Coast and East Texas.
As nocturnal feeders, snails and
slugs may rarely be seen feeding, but if you find slime trails around your
garden area and holes chewed in your leafy, green garden plants the culprits
are without a doubt snails or slugs.
Snails are mollusks; mollusks are
invertebrate animals with a soft unsegmented body usually enclosed in a
calcareous shell. While the snails themselves can be destructive to our
vegetation, they also serve as intermediate hosts to parasites, such as liver
flukes. The subject of liver flukes is way beyond this article, but suffice to
say depending on the area of the world
and the species of fluke in the environment - livestock, including
cattle, horses, sheep, pigs, and poultry, not to mention cats, dogs, and humans
may become infected by these damaging parasitic worms. So, in my book any dead
snail is a “good” snail - period!
Methods available for combating snails
and slugs in the garden include – chemical applications, non-chemical
applications, habitat modification, direct intervention, the introduction of
natural predators, and the selection of deterrent plants.
1) Chemical applications – Metaldehyde, is the active ingredient in
many off-the-shelf products and is the most common chemical used for combating snails
and slugs; however, there have been reports of children, pets – particularly
dogs and cats - and bird poisonings (some fatal) from ingesting this chemical.
If used, extreme care should be exercised in following all the manufacturer’s
label recommendations!
2) Non-chemicals applications - I lean towards integrated pest
management (IPM), especially the environmentally friendly methods. For example,
in lieu of the toxic Metaldehyde I prefer ferric
phosphate – sometimes known as iron
phosphate – it is commonly found in nature and is not harmful to humans,
birds, animals, or the environment. When applied on the soil in pellet form as
a bait, snails and slugs are attracted to and ingest the ferric phosphate
pellets which interferes with their digestion – the snails and slugs stop
eating and die within a few days. I have used ferric phosphate in my gardens
for several years now and have been very pleased with the results – and yes, it
may be used in an organic program with restrictions which require the use of
preventative, mechanical, physical, and other pest, weed, and disease
management practices. Check http://www.omri.org/omri-lists
for products such as “Sluggo” that contain ferric phosphate or visit your local
garden center.
It should be noted that some of
the ferric phosphate products available on today’s market contain active ingredients
other than just ferric phosphate – I do not use these products. As with all
substances you are going to place in your garden – whether a pellet, spray, or
powder – take the time to read the product label carefully and completely.
Identify the product’s active ingredients, target pests, how to correctly apply
the product, and any known hazards with its usage before you introduce
it into your garden! Any “extra” active ingredients may not meet organic
requirements. I often research active ingredients separate from product labels
to get a broader spectrum of information – and am often surprised over the
results of these independent searches.
During my research I came across
a staff publication by the USDA National Wildlife Research Center, University
of Nebraska – Lincoln. The publication reported on testing the use of a 2%
solution of caffeine sprayed either directly onto snails/slugs or on the soil
in which slugs have burrowed; they had success with this but also noted that it
did have some adverse effect on the surrounding plants. So, far, I have not
been able to find any indication that further testing has been done using
caffeine as a control method although there are many articles from many sources
on the Internet touting its use. Folks, my question is – will this caffeine
solution affect the pollen and nectar of plants? At this point, I do not know -
until and unless I see some test results from additional science centers, I
will forego using this method, mainly because of the pollinators – the birds,
all the different bees and other beneficial insects that I try to encourage to
take up residence in my garden. I know I can use other methods for control that
are safe and proven to work. Additionally, I have found some indication that
this method of control may not meet all organic program requirements; if you
are organic, be sure to check this out before using caffeine in the garden.
3) Habitat modification - Another approach is to alter the environment
which snails and slugs use as refuge and breeding grounds by removing debris
and dense ground cover, such as ivy and other succulents, stacks of boards and
wood, and large wood chip mulches from the garden area. Thin out the plants to improve
air circulation and use a mulch containing materials with thick, jagged edges
such as eggshells. Snails have soft underbellies and will avoid anything sharp
or prickly.
4) Direct intervention - Try utilizing barriers such as a simple line
of table salt around the outer garden bed, wood ash, diatomaceous earth,
sawdust, copper backed paper or sheeting, sand, sulphur, animal or human hair,
pine needles, thistle leaves, or straw. Keep an eye on your barriers as some of
them may need to be re-built from time to time, especially after a hard rain or
strong wind. Table salt, while very effective in combating snails, is fatal to
plants. It should be used sparingly and never applied directly to the garden
beds. Instead lay a small line of salt on a driveway or sidewalk that appears
to be a regularly traveled path for the snails or slugs.
Set traps - snails love sweet
things such as sugar water, fruit juice, soda pop and believe it or not, beer!
For a homemade trap using one of the liquids, partially fill a plastic pot with
a tight fitting lid and slots cut into the side, bury it in the ground to the
level of the opening. Snails fall in and are incapable of getting out of the
trap. Additionally, small boards raised slightly (1 inch) off the ground serve
as effective traps. Snails will attach themselves to the boards during the day
and can easily be found and destroyed. Commercially made traps are also
available through garden centers and the Internet.
Do hand combat – go out to the
garden, find, and hand pick the snails from your plants and surrounding areas,
such as trees, walls, and stones. Once captured, you can easily destroy the
snails by dropping them in salty water or crushing them.
5) Introduce natural predators - Bring in the support troops – fortunately
snails have many natural enemies; among them are frogs and toads. Whenever possible,
create a small pond in the garden to encourage frogs and toads to make their home
there. The smaller ones love self-watering pots. Frogs and toads are great – no
plant damage and they eat other garden pests, as well as snails! Chickens, ducks, and guinea hens consider snails
a tasty snack; people who own and allow them to free range seldom encounter
snail and slug problems on their property.
6) Deterrent plants - And
lastly, consider some plants for your ornamental garden that are less prone to
snail damage such as ornamental grasses, impatiens, rosemary, sage, lavender,
begonias, nasturtiums, narcissus, geranium (cranesbill), alyssum, roses,
daylilies, and hydrangea.
There is no need to live with
snails and slugs destroying your garden or compromising the health of you, your
pets, and livestock when you have so many different options available for
controlling them – and most are environmentally friendly as well!
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