A22-UncMter Farming, Saturday, January 22, 2000
(Continued from Page A 1)
dary. Manure must be recycled
back into the earth for much
needed plant nutrients. To
ensure, however, that vegetables
and fruit do not become contam
inated, according to the Cornell
specialist, it’s important to
follow a “common-sense” ap
proach to managing manure
and reducing the risk.
The culprit is E. coli 0157, a
bacterium that causes severe ill
ness, especially risky to young
children and people with com
promised immune systems.
Fruit and vegetable consump
tion has gone up 24 percent from
1970-1997. So as more fruits and
vegetables are consumed, there
is a disturbing upward trend in
the amount of cases of food
borne illness reported, noted the
Cornell specialist.
Increases in reported out
breaks can be attributed to the
technologies and information
distribution capabilities of the
agencies charged with tracking
foodborne contamination.
And foodborne illnesses are
increasing globally not just in
the United States.
A rise in the number of salad
bars in U.S. restaurants
comprised 35.4 percent of the
outbreaks from 1990-1998. Most
of the outbreaks are associated
with lettuce consumption, Ran
garajan said, and sprouts.
To stem the problem of food
borne illness, producers can do
their part to more carefully
manage manure around the
farm. “Learn about where the
original risk comes from, de
velop a plan and think about
what to do,” she said.
Because scientists still know
little about how the foodborne
disease organisms survive in the
environment, there are few al
ternatives. The organisms are
“übiquitous,” active everywhere
in the environment, she said.
E.coli 0157 survives the acid
conditions of the stomach and
can lead to some “awful
illnesses.”
But the microbes behave
much like other organisms in
plant diseases.
“Anything you do to manage
the manure to protect the envi
ronment,” said Rangarajan,
“will also protect the crop from
microbial contamination.”
Growers need to keep record
of manure rates, time of applica
tion, methods of incorporating
manure, and watch when they
plant.
Also, beware of what’s going
on with the water. Surface water
sources for irrigation can con
taminate crops with harmful
bacteria. The only source of
water should be potable drink
ing water that is regularly tested
for coliform bacteria.
All manure carries pathogens,
so it is important to make sure
the manure is incorporated into
the soil and enough time goes by
before planting a vegetable or
fruit crop.
As vegetable growers, Ran
garajan told those at the meet
ing to “be diligent about
management of manure.” No
manure should come in direct
contact with produce. Flies, she
said, can move off cull piles to
the clean produce. Cull piles
—Proper Manure Handling Key *
To Controlling Foodborne Illness
should be eliminated.
Composting manure serves to
kill much of the harmful bac
teria. The heat from microbial
breakdown kills the pathogens.
And it’s important, the Cor
nell specialist noted, to always
incorporate the manure. And
never, never sidedress with
manure.
About 120 days, at least, are
required from when the manure
is applied until the crop is har
vested. That means manure
must be applied in the fall, espe
cially to early planted and har
vested crops.
“Keep animals out of all
(packing and processing) areas
as best you can,” she said. And
choose a crop that is more up
right to minimize the risk. Use
crops that have no direct contact
with the soil, including those
with trellises or staking systems
and plastic mulch with drip irri
gation. Drip irrigation is safer
because the E.coli pathogens can
be carried in water. Keeping the
leaves and fruit dry ensures
good control.
If broadcast spraying or irri
gating, it is important to use pot
able water if close to harvest, she
noted.
At harvest, according to Ran
garajan, growers should pick
only dry fruit, leave any fruit
with fly droppings on it, use
clean totes, cool the product
quickly, and train workers in the
importance of handwashing on
a regular basis.
Totes can be washed in water
mixed with bleach at a rate of Vi
teaspoon per five gallons or one
pint per 100 gallons.
Keeping the produce cool
helps stem bacteria growth. At
95 degrees, one bacteria can
multiply to 20 million in 6.7
hours. At 40 degrees, the same
bacterial growth rate takes 16.7
days.
When hand washing, special
ists recommend at least 20 sec
onds rubbing with soap and
water.
By following these proce
dures, growers can stem possible
outbreaks. The product is safe
and producers don’t have to face
the problems endured with
recent outbreaks in several
states.
Plant Disease
Powdery mildew, early blight,
late blight these kinds of
problems can sprout up in cu
curbit and other fields. Penn
State has found some significant
differences in varieties and types
of control of these diseases in
several trials.
Following management strat
egies to reduce harvest loss be
cause of disease is crucial,
according to Dr. Alan Mac Nab,
Penn State Extension, at the
New Holland Vegetable Day.
Mac Nab demonstrated how
critical it is to watch for treat
ment resistance building up in
plant species. And varieties vary
in their resistance to fungi.
Many problems can be con
trolled simply by earlier plant
ing. Mac Nab noted that on early
plantings, 46 days passed before
early blight showed up; 30 days
in mid-season; and only 14 days
to the appearance of early blight
late in the season.
Growers should know that
late blight can be “very, very
Speakers at the New Holland Vegetable Day included, front from left, Dave
Miller, grower; Bill Troxell, PVGA executive secretary; and Larry Yager, Penn
State marketing agent. In back, Ed Herrmann, grower and Solanco Young Farm
ers Association adviser; Paul Hauser, grower from Oxford; Anusuya Rangarajan,
Cornell University vegetable specialist; Bob Rouse, Maryland University Wye Re
search and Extension Center; and Alan Mac Nab, Penn State Extension.
devastating, it can move very,
very fast, and can wipe out the
whole crop,” Mac Nab noted,
sometimes within a two-week
period.
To counter the blights, pur
chase disease-free tomato
plants. “Destroy the potato cull
pile,” he said. Blight can
overwinter and spread to local
fields, and you can “get in trou
ble early.”
And continue to rotate crops
AN EGG A DAY ...
Carol V. Gay
Professor Of
Cell Biology
And Poultry Science
Why does it take 24 hours, or so,
for a chicken to form an egg?
A short answer to this question
is the complexity involved. Egg
formation is a sequential, multi
step process.
The process begins when the
ovary releases an egg yolk com
plete with a cluster of embryonic
cells floating on its surface; techni
cally this is called the ovum, hi
15-30 minutes the funnel-shaped
open end of the oviduct engulfs the
yolk.
I saw a movie of this engulfinent
when I was a graduate student and
still remember how amazing this
was. How did the funnel know
where the ovum was?
Once engulfed, the yolk begins
its journey down the oviduct, a
tube that is 16-18 inches long.
Much of the oviduct is comprised
of a region, called the magnum that
manufactures and secretes proteins
to form the egg white, mainly albu
men and several other proteins.
The oviduct wall is muscular and
so can move the ovum along by a
to stem disease.
Vegetable Growers Association
Bill Troxell, executive secre
tary of the Pennsylvania Vegeta
ble Growers Association
(PVGA), spoke about the work
of the association in helping to
fund research, its work on pro
moting the industry, and about
the Mid-Atlantic Fruit and Veg
etable Convention.
The PVGA helped fund 14
gentle squeezing, pulsating action
that rolls the yolk in a slow prog
ressive spiral. The result is that by
the time the yolk passes through
the magnum it has become coated
with egg white and has taken on
the characteristic egg shape.
Transit time through the magnum,
which is about 13 inches long, is
2-3 horns.
The next segment of die oviduct
is called die isthmus; it is quite
short, about 1 inch in length, but
transit time is 1-2 hours. The
isthmus also secretes proteins, but
these proteins form a tough highly
cross-linked membrane, known as
the shell membrane, on the egg
white surface. This membrane will
serve as die foundation for eggs
hell formation.
Finally, the now well-defined
egg enters the last region of the
oviduct, the shell gland. The egg
spends 20-26 hours in this final
chamber. In the first few minutes, a
dilute salt solution diffuses into the
egg white, a process called plump
ing, causing the egg to swell to its
full size. Then, the eggshell is
formed as calcium carbonate crys
tals precipitate onto die shell
membrane.
The finishing touches of egg
formation include secretion of pig
ment and the water impervious
different projects. It also helped
fund many promotional efforts
statewide, along with money
from the Pennsylvania Depart
ment of Agriculture.
Through the PDA, PVGA
helped erect 23 billboards. The
PDA erected 70 more billboards
with the “Pennsylvania Pro
duce: Simply Delicious” logo.
Press releases, detailing the
work of the PVGA, reached 2.4
million readers.
cuticle. The egg is laid about a day
after tbc yolk began its journey in
the early morning hours of the pre
vious day.
As mentioned, there arc two
time-consuming steps in the egg
forming process: laying down die
egg white and forming the calci
fied shell. Could these processes
be forced to occur more rapidly to
increase egg production? This is
doubtful, because the structures
that form both egg white and eggs
hell have to be replenished. Penn
ing egg white protein requires
delivery of die protein building
blocks, die amino acids, to the
tissue that then builds new protein
by adding amino acids one fay one
to the growing ends of die protein
molecules. Amassing a large vol
ume of protein requires time.
Likewise, replenishing the sour
ce of eggshell calcium in the
medullary bone is also time con
suming. The laying hen wastes no
time in replenishing these stores.
While the shell is being formed,
new albumen is synthesized and
conversely, while albumen is
formed, calcium stores are
replenished.
Egg formation is a complex pro
cess and is tightly orchestrated by
many kinds of neuto-endocrine
controls.
Disturbances to the control
mechanisms result in cessation of
laying which can take many days
to recover. /Sk