And this week’s report from the CDC provided further evidence that my home garden is the safest source of food for my family. This report examines the links between food commodities and foodborne illness, identifying fresh produce as the most frequent offender… a whopping 46% of all cases! For historical perspective, fresh produce was linked to less than 1% of all foodborne illness in the 1970s, and less than 12% in the 1990s. Why is foodborne illness from produce on the rise?
Soil survival of Escherichia coli O157:H7 acquired by a child from garden soil recently fertilized with cattle manureKeywords:bacterial survival;cattle;contamination;enterohaemorrhagic;environmental manure;foodborne pathogenAbstractAims: This investigation was conducted to determine the survival of a naturally occurring Escherichia coli O157:H7 in garden soil linked to a sporadic case of E. coli O157 infection in Minnesota.Methods and Results: The presence and viability of E. coli O157:H7 was monitored in manure-contaminated garden soil for several weeks. Bacterial isolates were characterized using PCR and pulsed-field gel electrophoresis (PFGE). Isolates obtained from the patient and the garden plots during this investigation had indistinguishable PFGE patterns and had the same virulence factors (stx1, stx2, eaeA, ehxA). The E. coli O157:H7 levels obtained from the garden plots declined gradually for a period of 2 months, and on day 69 only one garden plot of four had detectable levels of pathogen. All plots were negative on day 92. The rate of decline in the soil samples stored at 4°C was faster compared with soil samples that remained in ambient conditions, and in refrigerated storage E. coli O157:H7 could not be detected after 10 days.Conclusions: E. coli O157:H7 strains can survive on manure-amended soil for more than 2 months, and this survival could be reduced by low temperature.Significance and Impact of the Study: This is one of the few reports that have investigated the survival of a proven virulent strain in naturally contaminated soil samples. This case stresses the importance of avoiding the use of raw cattle manure to amend soil for cultivation of foods, including soils in residential garden plots.
Although it’s a good idea to do it, it’s no guarantee.
The way in which you wash your produce may even put you at greater risk of contracting a foodborne illness. Take a sun-warmed tomato from your garden and plunge it under cold running water, and the gases within the tomato tissues contract, creating hydrostatic pressure that pulls in microorganisms. Improper wash-water temperatures have been responsible for numerous outbreaks, including Salmonella in mangoes and tomatoes. Experts recommend that rinse water be as close to the temperature of produce as possible (within 10 degrees Fahrenheit).
What are the rules for manure use in non-certified organic or conventional farms? With regards to ensuring food safety, none. Although many states mandate that farmers have a Nutrient Management Plan (to prevent nutrient runoff and subsequent pollution of streams), there are currently no restrictions on timing of raw manure applications for conventional farms. In fact, many conventional farmers lease their land to factory farms for manure disposal. Concentrated animal farm operations (CAFOs) produce well over 1 billiontons of manure each year – it has to go somewhere, and many conventional farms gladly allow the raw manure to be spread on their fields, both for the free fertilizer and the additional money.
In fact, many conventional farmers lease their land to factory farms for manure disposal. Concentrated animal farm operations (CAFOs) produce well over 1 billiontons of manure each year – it has to go somewhere, and many conventional farms gladly allow the raw manure to be spread on their fields, both for the free fertilizer and the additional money.
Do not use manure from carnivores
Why is it important to properly cool vegetables, wash them, and dry them well before storing in your refrigerator? Unlike most human pathogens, soil-inhabiting Listeria can grow in the cold temperatures of a refrigerator, especially under moist conditions (albeit more slowly than on your countertop).
Site history:Flood-prone?Animals?Chemical contamination?Heavy metals?Polluted run-off?
Grow Your Own, Nevada! Summer 2013: Reducing Food Safety Risks in School and Community Gardens
Reducing Food Safety
Risks in School &
Grow Your Own, Nevada!
450 outbreaks of foodborne illness in the
U.S. due to fruit and vegetable
That’s 46% of all cases!
48 million sickened each year.
130,000 hospitalizations and 3,000
…and it’s not just large operations
Home, school and
community gardens are
Most illnesses that are
linked to home gardens
resulted from freshly
spread raw manure.
Some of the bad guys
Hepatitis A virus
Shigella Hepatitis A virus
Myth 1: Washing or peeling
produce is sufficient to remove
Prevention of microbial contamination is
the most important food safety element.
Bacteria and viruses are not easily
washed off of fresh produce.
sticky biofilms on
Microbes get inside the leaves
Saldaña et al. 2011
Rinsing with cold
water makes it
Use warm rinse
just before you
Myth 2: Organic produce is more
likely to cause foodborne illness.
Both conventional and organic growers
use manure as a fertilizer.
Manure use on certified organic farms is
There are no rules for use of manure in
Organic rules for manure use
The National Organic Program (NOP)
specifies that if manure is not composted,
it must be tilled into the soil:
◦ at least 120 days before the harvest of a food
crop that comes in contact with soil (like leafy
◦ or at least 90 days before the harvest of a crop
that does not come into contact with the soil
Use manure safely
Make sure your
compost reaches at
least 131 degrees,
manure in the fall
BEFORE you intend
Myth 3: Bacteria are killed by
Pesticides sprayed on food crops do not
Spraying pesticides can actually cause
Some pesticide formulations actually
support the growth of bacteria in the
pesticide holding tanks.
Safe pesticide use
Read the label to make
sure it’s labeled for use on
Use potable water to mix.
Have well water tested for
Mix only the amount of
pesticide that you need for
a single application.
Avoid pesticide use in
Myth 4: I don’t apply manure to
my garden or have pets, so I don’t
have to worry about pathogens.
rabbits, squirrels, birds, moles, voles, mar
Many pathogenic organisms are native to
soils (ex. Listeria).
Improperly brewed compost teas are a
potential source of pathogens.
Hand sanitizer if
soap not available.
Disposable gloves is
also an option.
Handwashing rules for the garden
Scrub nails and fingertips with a brush.
Wet hands with clean running water and
Scrub the backs, between fingers and under
Rinse well and dry with a single-use towel.
Myth 5: Since I am growing my
own food, I don’t need to wash or
refrigerate it after harvesting.
Most foods are safer if they are washed,
dried and stored in the refrigerator.
◦ Exceptions: tomatoes, potatoes, berries - wash
them right before you consume them.
For produce that contacts the ground as it
grows (ex. cantaloupes)
◦ Wash with a vegetable brush (to remove dirt
stuck in their netted skins) and dry completely
Minimize site risk
Industrial sites or
Best to establish a
Urban soils carry greater risk
Test soils for the
presence of heavy
Copper and zinc are
not a risk to you
but levels may be
too high for plant
Water is the mostly
likely vehicle to put
Best source is
Use drip irrigation
to minimize contact
with edible parts.
Water quality of other sources
Have water tested for coliform and
generic E. coli (indicator of fecal
Consider contamination from domestic
waste, nitrates, petroleum
residues, heavy metals.
Avoid unregulated sources
for school and community
What about rainwater?
Fine for watering ornamental plants, but…
Test for E. coli if it is used on edible
◦ Age of roof
◦ Materials (metal?)
◦ Air quality
◦ Slope of roof
Gardens and allergens
Some gardeners (or children!) have
serious food allergies
Avoid planting (or bringing into the
garden) common allergens:
◦ Peanuts or peanut butter
◦ Soybeans, soy milk, tofu products
◦ Tree nuts
Turn pile once per week (but not more
than every three days).
Internal temperature of compost pile over
130 degrees Fahrenheit for 5 days to kill
Use of composted manure NOT
recommended for school gardens.
Turn the pile
Making compost safe for pets and
Do not leave food
scraps lying on top
of the pile.
produced by a
mold that causes
Pesticides are not
by the composting
Compost tea is not the dark-colored
solution that leaks from the bottom of the
compost pile (do not spray this on food
Compost tea is the extract of compost
made suspending compost in a barrel of
water (aerated or unaerated) for a short
period of time (up to a week).
What is compost tea?
Use only potable water.
Sanitize all equipment.
Use only compost that has maintained a
temp of 131 F for 3 days (hot composting
Must be used within 24 hours of making
Avoid additives (esp. simple sugars like
If you decide to make compost