The Rural Voice, 1989-12, Page 72directory
HAVE SAW
WILL TRAVEL
Simon
Koopman's
Custom Sawmilling
Service Throughout Ontario
Greetings and Good Wishes
for the Holiday Season
Box 671, Harriston, Ont.
NOG 1Z0
519-338-2527
George Smyth
Welding
and
Machine Shop Ltd.
• Livestock & Flatbed Trailers
• Snowblowers
• Wood Splitters
• Bale Forks & Feeders
Holiday Greetings to all our customers
from the Staff and Management
at George Smyth Welding
R.R. 2 Auburn, Ont.
519-529-7212
When You Want
More Than Your
MONEY'S WORTH
in
BACTERIAL
INOCULANTS
Call the Probiotic Specialists
FOR THE BEST
PRODUCTS, SERVICE AND PRICE
BIO - TECH
Corporation
NUHN BIO -TECH
Stratford
N5A 6S6
519-393-5770
directory
VALmETAL
Silo Unloaders
Feed & Bale Conveyor
Feed Mixers
Jim QUALITY we're PROUD
‘o a\\ CANADIAN
ST GERMAIN, QUEBEC
Ontano Region
Atwood 519-356-2818
DENNIS PIERSON
CHEV OLDS LTD.
Your neighbourhood Chev-Olds dealer
• SALES • LEASING
• NEW • USED
No credit application refused
Tim Lenathen
856 Queen St.
KINCARDINE
519-396-3367
We're in
BUSINESS
to keep you
WORKING
• Chisel Plow Points
• Mould Board
• Shins
• Landsides
• Coulter Blades
• Grill Guards
• Roller Chain
• Gathering Chain
• Plow Points
• Grade 8 Fine Thread Bolts
• Grade 5 Coarse Thread Bolts
• Cultivator Points
• Disc Blades
• Hand Tools
• Shop Tools
Merry Christmas!
We look forward
to serving you
in 1990.
Hugh Parsons
BOLTS & TOOLS LTD.
11/4 miles east of Hensall
519-263-5681
70 THE RURAL VOICE
L
WHAT'S NEW
INTERACTION OF
PESTICIDES STUDIED
by Ian Wylie-Toal
Recent evidence from Britain may
cause some re -thinking about how
safety limits for pesticides are set.
The magazine New Scientist re-
ported in October that workers at the
University of Reading and the Institute
of Terrestrial Ecology at Monks Wood
in England have found that quail that
consumed a fungicide were killed by
subsequent exposure to malathion, even
though levels of the individual chemi-
cals were well below safety limits.
Quail given oral doses of the fungi-
cide prochloraz showed an increase in
the level of an enzyme called cyto-
chrome P450.
Cytochrome P450s, which are natu-
rally present at low levels in birds such
as quail, are known to change organo-
phosphate insecticides from inactive
forms to more toxic active forms.
This led scientists to suspect that
birds with the higher levels of cyto-
chrome P450 would be poisoned by
lower than expected levels of pesticides
such as malathion.
So they fed quail prochloraz at a rate
of 180 mg per kg of body weight. The
birds were then injected with low doses
of malathion (5.6 to 11 mg/kg), which
killed them.
When the malathion was given
orally to prochloraz-treated birds, they
did not die but showed the first signs of
organophosphate poisoning. Control
birds, which received the malathion but
not the prochloraz, were unaffected by
the insecticide.
Dr. Gerald Stephenson, a professor
of Environmental Biology at the Uni-
versity of Guelph, says the findings are
significant because they demonstrate
that there can be unexpected toxic ef-
fects between unrelated pesticides.
He adds that there are other recorded
incidents of unexpected toxic effects
between pesticides. He has published
papers which show that insecticides
applied to crops have inhibited the
plants' metabolism of herbicides, re-
sulting in unexpected damage to the
plants.
Other studies have shown that some
herbicides affect how plants metabolize