Yard
and Garden
May
23, 2015
Q. I have a question today is
related to rabbit wire or 1/2" by 1/2" wire. We use this to keep
squirrels, snakes and birds, etc. out of our garden.
While installing this wire I noticed that it is coated with lead. In the past
we have used bird netting which worked well but over time breaks down and holes
appear, thus letting these pests rob us of our vegetables. The question is,
does the lead (toxic material) pose a problem over time breaking down then
leaching into the soil? Also will the plants absorb the metal and translocate
them to the edible parts of the plant? We grow mostly tomatoes, chiles, and a
few types of lettuces.
A.
Are you
sure the wire mesh is coated with lead? Most of fencing materials such as
what you have described are galvanized – coated with zinc. Lead is indeed
toxic if you ingest it in sufficient quantities. Lead paint was banned
from household paints many years ago and more recently from paint used for toys
and furniture. The problem was mostly from direct ingestion of paint
chips or children chewing on painted surfaces. Elemental lead (metallic
lead) used to coat wire would be very insoluble in water at pH
(acidity/alkalinity) levels common in the garden environment. In this
form it has a high affinity for soil particles and will bind to the soil and
will not be easily absorbed by plant roots. Since minerals must be
dissolved in water to be absorbed by plants, the chances for entering the
plants and creating toxicity problems are minimal. Even plant leaves
(lettuce) that come into direct contact with elemental lead will probably not
absorb the lead, but there would be a very small chance that it could be
adsorbed on the leaf surface. Keep lettuce plants and whatever will be
eaten from directly contacting the wire, if it is coated with lead.
Check your fencing material again to be sure it is indeed lead that has been
used to coat it. It is more likely to be coated with zinc. Zinc is
a plant micronutrient, meaning that plants need small quantities of it so you
ingest zinc when you eat plant materials all the time. In high
concentrations it can be toxic, but that is again very unlikely. Many
people actually take zinc dietary supplements. Zinc is also relatively
insoluble in water at pH levels common in the garden. We must sometimes
treat soil or plants with zinc to overcome deficiencies in the plants.
If the wire proves to be coated with lead you may want to purchase galvanized
fencing material. You can tell the difference because lead is quite soft
and easily scratched from the surface of the wire. Zinc is much harder
and will require steel or some hard material to scratch it from the wire.
Send
your gardening questions to Yard and Garden, Attn: Dr. Curtis Smith, NMSU
Agricultural Science Center, 1036 Miller Rd. SW, Los Lunas, NM 87031. You may
also send to cwsmith@nmsu.edu or leave a message at https://www.facebook.com/NMSUExtExpStnPubs. Curtis W. Smith,
Ph.D., is an Extension Horticulture Specialist, retired from New Mexico State
University’s Cooperative Extension Service. NMSU and the U.S. Department
of Agriculture cooperating.
