Snails can be found in many
habitats and can sometimes be pests not only in our landscapes. But can be highly detrimental to plants in production. In Nigeria there are numerous native and newly
imported snail species. Most land snails are not pests. They feed on algae and fungi, a few are
predatory. Some tree snails are
considered endangered and are protected.
However, there are several species that are pests and require
management, but it is imperative that the snail is identified as a pest before
treatments are initiated.
Most recently, one of the worst
snail pests in the world, the giant African land snail, was found in Miami-Dade
County. It has been observed to feed on
more than 500 different plants and also presents a human health hazard because
it can transmit
disease organisms to plants and animals, including humans. Most of the feeding damage is expected to be on vegetables, flowers and other ornamental plants and to annual weeds. It also has an affinity for substrates with calcium for shell building and can often be found on the side of concrete buildings or building materials (http://edis.ifas.ufl.edu/in904).
disease organisms to plants and animals, including humans. Most of the feeding damage is expected to be on vegetables, flowers and other ornamental plants and to annual weeds. It also has an affinity for substrates with calcium for shell building and can often be found on the side of concrete buildings or building materials (http://edis.ifas.ufl.edu/in904).
Management of Snail
To date, there is little
information available on the management of the giant African land snail. However, there is information available for
general snail management, but many of the methods have not been proven on a
snail of this size. Growers in south
Florida and particularly in Miami Dade County should be on the outlook for the
giant African land snail. Steps can be
taken to minimize the likelihood of snail introductions and establishment in
nurseries. Plants and other articles
coming into the nursery should be inspected for snails and initially
segregated. Growers should establish a
snail identification/education program for all employees and an ongoing
monitoring program so that any suspect snail can be identified and steps taken
to potentially eradicate or control snail infestations as early as possible. Snails
are generally active at night and on cloudy, rainy days. They seek shaded, sheltered resting locations
with high humidity when general environmental conditions are hot and dry. In south Florida where much of the year is
humid or wet, snails can be found anywhere.
As we move into the dryer, winter months, the snails may seek moist
areas or areas under irrigation. When
conditions become unfavorable, snails can become inactive or go into a
“resting” period called aestivation in which they withdraw into their shell and
do not feed.
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Control is typically not
possible if snails are in this “resting” condition.
1. Monitor
a. At night, search for presence of the snails.
b. During the day, search for snail trails and damage
c. Pay particular attention to moist areas or very
susceptible plants such as seedlings or more succulent plants.
d. Trapping - various types of traps or attractive items can
be used to lure snails. Banana and
papaya are particularly attractive to the giant African land snail and can be
used to catch them. Most traps only work
for snails in the immediate vicinity.
e. While monitoring, handpicking snails will help. If done thoroughly and on a regular basis it
can be an effective control method.
Gloves should always be worn when handling snails.
2. Unfriendly snail environment – Modify your environment to
reduce the number of snails
a. Remove hiding places such as boards, stones, debris,
weedy and leafy branches growing close to the ground, dense ground covers, etc.
b. If possible, create a less humid environment (i.e. less
irrigation; drip irrigation versus sprinkler)
c. Place copper foil or screening on benches or around areas
for protection
d. Dry, abrasive materials such as diatomaceous earth can
also be used as a barrier, however, once wet it no longer works. This method may not be suitable for some
situations but should be considered if feasible and if the material can be kept
dry.
3. Treatment
a. Iron Phosphate (Sluggo; Escar-Go; numerous
over-the-counter products)
i. Product must be ingested; snails are sensitive to iron
toxicity
ii. Causes snails to stop feeding.
iii. Safe for use around animals.
b. Metaldehyde baits (Deadline; Trails End; Slugfest;
several over-the-counter products) -
Probably most widely used and has been shown to be
efficacious against many snail pests.
i. Toxic both by contact and ingestion
ii. Breaks down rapidly in moisture and sunlightOctober 2011
iii. Poisonous to pets and wildlife; Use care when using,
however, these products
are not restricted use and are available in professional and
over-the-counter products.
iv. Different formulations (pellets, mini-pellets, coarse
meal, and liquids); some
Formulations are combined with carbaryl).
v. Most effective under warm temperatures; low humidity.
vi. Sometimes snails can recover after ingestion
particularly if they can get to water or moist conditions.
c. Methiocarb (Carbamate)
i. Sold as a spray and bait formulation (Mesurol 75WP,
Mesurol Pro).
ii. Sometimes used in combination with metaldehyde.
iii. Less effective under cool, wet conditions.
iv. Fast acting; stomach and contact poison.
v. Restricted use pesticide.
d. Borates – Baits containing boric acid.
i. Inhibit respiration.
ii. No resistance to these products is likely to occur.
iii. More effective against slugs than snails but may be
effective against giant
African land snail.
e. Repellents – These products do not control the pest but
help to keep them out of certain areas much the same as placing copper
barriers. Examples include garlic
extract, cinnamon oil and Bordeaux mixture (copper sulfate and lime). Other products are being reviewed, but often
these may not be feasible in a production environment.
NOTE: When using
baits, it is best to use after watering or irrigation, however, try to place
the
bait in drier areas.
Do not water or irrigate after applying bait.
NOTE: Use of
mollusicides should be in accordance with the label instructions. It is important that identification of the
target snail is determined before application.
Florida has many endangered and protected snails that could be harmed in
improper use of pesticides.
f. Natural Enemies – In general there are numerous natural
enemies that feed on snails which include ground beetles, pathogens, snakes,
toads, turtles, and birds, but most do not usually provide satisfactory
control. However, there are no proven,
commercially available natural enemies for snail control currently available in
the U.S. In California, the use of a
predatory snail was approved to use in citrus orchards for brown citrus
snail. The use of the predatory snail
was combined with several other methods to manage the snail. October 2011, approaching snail management in
an integrated approach will likely be necessary. In California, a successful snail management
program for brown citrus snail included the release of a Predatory snail, use of copper bands, pruning, applications
of copper sulfate and iron. Phosphate, metaldehyde and a foliar application of phosmet
which was allowed under a special Exemption.
In the future, the development of a specific management program for the
giant African land snail may be necessary.
At this time, it is imperative to monitor for these snails as they are
being found at numerous locations within Miami-Dade County and to manage any pest
snail problems within your production area.
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