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has not necessarily been viewed by growers as an important
behavior and has been identified as a key area needing
improvement in several studies (5, 6, 10, 12). A survey
conducted in Kentucky found that only 36% of survey
respondents recognized that produce wash and rinse water
was a potential source of microbial contamination (12).
Additionally, postharvest treatment of water was identified as
one of the needed areas of improvement among Minnesota
farmers (6). Harrison et al. (5) reported use of unapproved
sanitizers, such as vinegar, detergents, ammonia and water,
and sulfur/citric acid solutions, in several states in the
Southeastern U.S., further identifying produce washing as
a practice that specifically needed attention to reduce the
risk of foodborne illnesses. In a more recent study, 75% of
growers surveyed agreed that the addition of sanitizer to
postharvest water helps reduce the microbial load (9).
Not surprisingly, this study discovered a wide spectrum
of sanitizer use practices among produce growers. As
previously stated, chlorine-based sanitizers have been the
most commonly used sanitizers in the fresh produce industry
for decades (2, 3, 8). Unfortunately, the antimicrobial activity
of these sanitizers depends on several factors, including
water temperature, pH, water hardness, contact time, amount
and rate of product throughput, type of product, water to
product ratio, amount of organic material, and the resistance
of pathogens to the particular antimicrobial agent (13).
Sanitizer selection and concentration depends specifically
on wash water system (e.g., spray bar, recirculated), organic
load, type of produce, and volume of produce, among other
variables/factors. There is no universal recommendation
for all wash water practices, which makes it difficult to
meet specific grower needs. Furthermore, when using
chlorine, it is extremely important to monitor free chlorine
concentration to ensure that the wash water is effective,
because chlorine binds to organic material in the water.
Chlorine-based sanitizers were the most common sanitizers
used by the produce growers surveyed in this study, although
concentrations added were often incorrect, or were not
consistently measured to ensure use of recommended
concentrations. We observed that about half of the growers
surveyed used sanitizer concentrations that were too high
or too low, or did not know what concentrations they use.
Consistently using correct sanitizer concentrations is a
common problem for growers (5, 10). For example, 16%
of growers in New York added chlorine at correct levels
(for their intended use) ranging from 50-200 ppm (10).
Because of the increased emphasis on fresh produce safety
and grower practices over the last two decades, we expected a
higher percentage of growers to be using sanitizers correctly.
Unfortunately, even if concentrations used are initially
correct, the amount of free chlorine can change rapidly
during the wash period; therefore, monitoring is essential.
Our study found that as many as 20% of growers either do
not monitor sanitizer concentrations at all or measure it

through non-recommended methods, such as smell. Our
survey did not ask about frequency of monitoring, but it
has been previously reported to vary significantly (5, 10).
Overall, this study shows improvement in sanitizer usage
(compared with previous studies), but it is clear that a more
targeted educational campaign is needed to provide Virginia
growers with specific recommendation based on their
intended use.
Preferred delivery method for educational materials
There have been many surveys assessing preferred educational delivery methods for growers. As discovered in this
study, growers rely on education and training opportunities
from several types of resources. There is great interest in GAP
training programs through online trainings, websites or videos;
however, cost and lack of time are often primary barriers (12).
On-farm food safety trainings contribute to increased knowledge and perceptions of food safety practices among growers,
but it is important to understand the practical barriers
confronted by growers to implementing these practices and
to utilize that knowledge for developing effective educational and outreach plans (9). In this study, we identified a
preference on the part of growers to get information (e.g.,
on produce washing) from Cooperative Extension through
grower meetings. This data could be biased, however,
because the survey was conducted with participants already
engaging with cooperative extension at a grower meeting.
A small percentage would also want to receive educational materials through written fact sheets, online trainings,
video recordings, audio/podcast. In Virginia, future plans
for implementing additional training for growers on the
topic of post-harvest water sanitation will be a multipronged approach, including clientele we already interact
with at grower meetings, but expanding to include distance
learning video recordings and podcasting to broaden our
reach, as well as one-on-one consultations in sanitizer use to
improve correct usage.
CONCLUSIONS
Human pathogenic bacteria can be transmitted through
contaminated water; therefore, managing wash water
quality during post-harvest washing can play a key role
in mitigating food safety risks. Water parameters, such as
initial microbial quality, pH, temperature, and turbidity,
affect appropriate sanitizer selection for use with various
types of produce and washing systems. Selecting the correct
sanitizer and using the recommended concentrations in
wash water maintains the microbial quality of wash water
and prevents cross-contamination of produce. Produce
growers are not necessarily aware of the importance of using
recommended concentrations and therefore may not follow
the standard protocols to prepare and monitor sanitizer. This
study found that far too many growers were using incorrect
concentrations of the sanitizers that they were using. This

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