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of the apple placement. Each site should be covered with
split rubber tires, sections of straw, wood slabs, shingles,
tar paper, etc.
 The number of voles that can be tolerated is a trade-
off between cost of control and cost of damage. Most
damage occurs at high population levels. Monitoring
vole populations is essential to allow growers to assess
when populations are increasing, and when there is a need
to begin control programs.
The preferred method for vole control is to utilize
herbicide strips on each side of the tree to eliminate all
sod and weeds. Voles do not like to cross bare ground for
fear of natural predators.
Control of ground vegetation with herbicides,
mowers, or disking helps limit voles by reducing
potential cover for their surface runways. However,
mechanical methods of working the rows leave heavy
cover directly around the tree base, concentrating the voles
in these areas. Clearing a 3-foot radius around the base of
the trunk is important to eliminate this cover. Overall,
herbicides are the preferred method to eliminate sod.
Cultural practices have definite limitations and
should not be relied upon as a complete control for voles.
The orchard floor should be kept clear of debris such as
bags, boxes, and pruned branches, since these items
provide protection to voles, and can hinder mowing and
proper bait placement. A final close mowing of the row
middles in early November after harvest should be utilized
annually to further reduce habitat and cover for rodents.
New Jersey Pesticide Law requires the use of tamper-
resistant bait stations. Placement of baits at two or three
locations inside the drip line of trees for one week will
help determine vole activity. If voles are present, you
will find vole activity under some of the shingles, tires,
etc. that show vole activity. Use of these items as bait
stations has been determined to be acceptable under NJ
Pesticide Law. If a herbicide strip exists, vole monitoring
must be done in adjacent cover because voles will seldom
range on bare ground. Zinc phosphide baits are classified
as restricted use pesticides in NJ, and can only be applied
by registered pesticide applicators. Additional
information regarding use of pesticides can be obtained by
calling the NJ Bureau of Pesticide Control (609) 530-
4070.
Zinc Phosphide Baits.If possible, set out baits
when a dry spell is expected (3-4 days). Rain or damp
conditions quickly reduce bait effectiveness. Pelleted zinc
phosphide bait formulations are currently available to the
apple industry. Care must be taken to read the label to
determine if a specific product is still currently labeled for
New Jersey. Some rodenticides labeled in New Jersey are:
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Bonide Orchard Mouse Bait (Bonide Products Inc.);
Zinc Phosphide Bait & Pellets
(Hacco, Inc.)
Zinc Phosphide Corn Bait (Hacco, Inc.)
Ridall-Zinc Rodent Field & Agricultural Bait
(Liphatech Inc)
Zp Rodent Bait Ag
(Bell Labortaries Inc.)
Gastoxin Fumigation Pellets
(Bernardo Chemicals Ltd)
Zinc Phosphide Concentrate For Mouse Control
(USDA-APHIS)
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Zinc phosphide concentrate (63%) for making your
own bait can be purchased from the USDA-Animal and
Plant Health Inspection Service-Wildlife Services by
contacting: Janet L. Bucknell, State Director, USDA
APHIS WS, 140-C Locust Grove Road, Pittstown NJ
08867. Phone: 908-735-5654, Fax: 908-735-0821. ZP
Rodent Bait AG made by Bell Laboratories is reportedly
superior to grain baits for the control of pine and meadow
voles. Hand placement of this material under covers or in
holes and runs will control both species. If populations
are high, a second application using an anticoagulant may
be required.
Apple bait treated with zinc phosphide concentrate
should be applied in the fall before the ground freezes.
Apple baits should be mixed just before placement and
not held for more than one day. Zinc phosphide grain
bait applied by hand has not given adequate control of
pine voles or heavy meadow vole populations due to poor
bait acceptance. Zinc phosphide-coated apple slices are
more effective than grain baits, but neither is considered
adequate in a single baiting per year for pine voles.
systematically for the distinctive trails that voles make
under heavy cover. Fresh grass clippings and feeding on
fallen fruit are evidence of vole activity. Abandoned runs
may have thread-like fungus growth, green grass shoots,
and fine root growth. When baiting, glance ahead to pick
up probable spots for bait placement. Clumps of grass,
old fertilizer bags, apple crates, and bales of hay are
usually good locations. Examine one side of a tree at a
time, looking for runs under the drip line. Move in
toward the base until a run is found or a tree location is
considered inactive. Disturb the area as little as possible.
When an active run is located, place a treated apple
cube or a teaspoonful of grain bait in the runway. Use
both baits where pine voles occur. Usually three or four
baits per tree are ample. Pull the grass back in position
over the baits. When runways are found between tree
rows, bait them also. Where voles have been feeding on
roots below ground level, a complete baiting program is
in order. Trees damaged by this type of injury may have
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