1. Reducing Food Safety
Risks in School &
Community Gardens
Heidi Kratsch
Grow Your Own, Nevada!

2. We’ll cover:
 Myths
 Site selection
 Soil
 Irrigation
 Compost
 Garden design
 Sanitation
 Volunteers

3. Some facts:
 450 outbreaks of foodborne illness in the
U.S. due to fruit and vegetable
production.
 That’s 46% of all cases!
 48 million sickened each year.
 130,000 hospitalizations and 3,000
deaths.

4. …and it’s not just large operations
 Home, school and
community gardens are
at risk.
 Most illnesses that are
linked to home gardens
resulted from freshly
spread raw manure.

5. Children are more susceptible
than adults

6. Some of the bad guys
 Campylobacter
 Cryptosporidia
 E. coli
 Hepatitis A virus
 Listeria
 Norovirus
 Salmonella
 Shigella Hepatitis A virus

7. Myth 1: Washing or peeling
produce is sufficient to remove
pathogens.
 It’s not!
 Prevention of microbial contamination is
the most important food safety element.

8. Bacteria and viruses are not easily
washed off of fresh produce.

9.  Bacteria form
sticky biofilms on
food surfaces.

10. Microbes get inside the leaves
Saldaña et al. 2011
 Rinsing with cold
water makes it
worse!
 Use warm rinse
water.
 Peel vegetables
just before you
consume them.

11. 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
strictly regulated.
 There are no rules for use of manure in
conventional operations.

12. Concentrated Animal Feeding
Operations (CAFOs)

13. 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
greens),
◦ or at least 90 days before the harvest of a crop
that does not come into contact with the soil
(like corn).

14. Use manure safely
 Compost your
manure.
 Make sure your
compost reaches at
least 131 degrees,
or
 Amend with
manure in the fall
BEFORE you intend
to plant.

15. Myth 3: Bacteria are killed by
pesticides.
 Pesticides sprayed on food crops do not
kill bacteria.
 Spraying pesticides can actually cause
microbial contamination.
 Some pesticide formulations actually
support the growth of bacteria in the
pesticide holding tanks.

16. Safe pesticide use
 Read the label to make
sure it’s labeled for use on
crop plants.
 Use potable water to mix.
 Have well water tested for
microbes.
 Mix only the amount of
pesticide that you need for
a single application.
 Avoid pesticide use in
school gardens.

17. Myth 4: I don’t apply manure to
my garden or have pets, so I don’t
have to worry about pathogens.
 What about
rabbits, squirrels, birds, moles, voles, mar
mots...?
 Many pathogenic organisms are native to
soils (ex. Listeria).
 Improperly brewed compost teas are a
potential source of pathogens.

18. Handwashing
You need:
 Potable running
water.
 Soap.
 Single-use towels.
 Hand sanitizer if
soap not available.
 Disposable gloves is
also an option.

19. Handwashing rules for the garden
 Scrub nails and fingertips with a brush.
 Wet hands with clean running water and
apply soap.
 Scrub the backs, between fingers and under
nails.
 Rinse well and dry with a single-use towel.

20. 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
before refrigerating.

21. Prevent Listeria outbreaks!

22. Site selection

23. Minimize site risk
 Industrial sites or
neighborhoods pose
a risk.
 Best to establish a
long-term
arrangement with
the landowner.
 Need good
community support
for garden
longevity.

24. Urban soils carry greater risk
 Test soils for the
presence of heavy
metals (lead,
arsenic).
 Copper and zinc are
not a risk to you
but levels may be
too high for plant
growth.

25. Water Quality
 Water is the mostly
likely vehicle to put
pathogens in
contact with
produce.
 Best source is
municipal.
 Use drip irrigation
to minimize contact
with edible parts.

26. Water quality of other sources
 Have water tested for coliform and
generic E. coli (indicator of fecal
contamination).
 Consider contamination from domestic
waste, nitrates, petroleum
residues, heavy metals.
 Avoid unregulated sources
for school and community
gardens.

27. What about rainwater?
 Fine for watering ornamental plants, but…
 Test for E. coli if it is used on edible
plants.
 Roof run-off:
◦ Climate
◦ Age of roof
◦ Materials (metal?)
◦ Air quality
◦ Slope of roof
◦ Temperature

28. 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
◦ Corn
◦ Wheat
◦ Tree nuts

29. Safe composting
 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
(most) pathogens.
 Use of composted manure NOT
recommended for school gardens.

30. Pile
heats
up
Temperature peaks
Pile
shrinks
160 F
Turn the pile

31. Use a compost thermometer

32. Making compost safe for pets and
children
 Do not leave food
scraps lying on top
of the pile.
 Tremorgenic
mycotoxin is
produced by a
mold that causes
tremors.
 Pesticides are not
reliably degraded
by the composting
process.

33. Fence off composting areas

34. Safe compost location?

35. What about compost
tea?

36.  Compost tea is not the dark-colored
solution that leaks from the bottom of the
compost pile (do not spray this on food
crops!)
 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?

37.  Use only potable water.
 Sanitize all equipment.
 Use only compost that has maintained a
temp of 131 F for 3 days (hot composting
method).
 Must be used within 24 hours of making
it.
 Avoid additives (esp. simple sugars like
molasses).
If you decide to make compost
tea:

38. Worm composting and kids

39. Gardens and animals

40. Sanitation and tools
 Wear gloves when harvesting.
 Wash hands before and after harvesting.
 Tools should be sanitized before and after
use.
◦ No more than 1 T. bleach to one gallon water.

41. Other garden activities

42. Volunteer management
 Develop safety
rules.
 Provide an
orientation.
 Make it easy to
follow the rules.
 Set a good
example!
 Post signs.
CLEAN HANDS.
CLEAN WATER.
CLEAN SOIL.
CLEAN SURFACES.