Research Plant Pathologist
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Dr. Wojciech J. Janisiewicz 2217 WILTSHIRE ROAD
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Education and Degrees
1983 Ph.D. Plant Pathology. Washington State University, Pullman, WA.
1979 M.S. Plant Pathology. Washington State University, Pullman, WA.
1975 B.S.eq. Horticulture. Academy of Agriculture, Krakow, Poland.
1965-1970 Horticultural High School. Pomologia-Proszkow, Poland.
Experience
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1984 to Present |
Research Plant Pathologist, USDA, ARS, Appalachian Fruit Research Station, Kearneysville, WV |
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1983 September - December |
Temporary Appointment, Tree Fruit Research Center, Washington State University, Wenatchee, WA, Postharvest Pathology, Collaborative research with Stemilt Storage |
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1977 April - September |
Laboratory Technician, Tree Fruit Research Station, Washington State University, Wenatchee, WA |
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1976 - 1977 |
Orchard worker, Columbia River Orchard, Rock Island, WA |
Professional Work Experience
For the past three decades, my research has been focused on studies of the epiphytic bacterial and yeast microbiota of pome and stone fruits and its potential for biocontrol of postharvest diseases of fruits. This research resulted in a large collection of bacterial and yeast antagonists effective against blue mold, gray mold and bitter rot of apples and pears, brown rot of stone fruits, and gray mold of strawberries. One bacterial antagonist, a saprophytic strain of Pseudomonas syringae, was developed into a commercial product, BioSave®, which has been successfully used for control of postharvest diseases of fruits and vegetables for over 20 years. For another very effective antagonist, Pseudomonas cepacia (now Burkholderia cepacia), we characterized the mechanism of biocontrol that was based mainly on a powerful antifungal compound, pyrrolnitrin. Subsequently, Syngenta developed several analogs of this compound, one of which, fludioxonil, is currently the most widely used commercial fungicide for control of postharvest decays of fruits and vegetables. Some of our antagonists, including the one in BioSave®, in addition to controlling plant pathogens can also curtail the development of foodborne pathogens that have been the source of many outbreaks lately. Physiological and ecological studies of our antagonists have led to the development of mutually compatible antagonist mixtures with superior biocontrol potential over the individual antagonists. Limitations of the biocontrol approach have been addressed by developing a “hurdle system” where biocontrol is combined with other alternatives to synthetic fungicides and has resulted in the development of fruit decay control strategies equivalent to fungicide treatments that are safe, environmentally responsible, and compatible with organic fruit production and storage.
We are continuously searching for sustainable alternatives to synthetic fungicides for control of postharvest diseases. In this pursuit, we recently found resistance to blue mold and bitter rot in a wild apple collection originating from Kazakhstan, the place of apple origin. The usefulness of this resistance to breeding programs is currently being investigated. Also, a novel, more effective application of UV-C irradiation to strawberry plants and fruit for control of gray mold, anthracnose and powdery mildew is being developed and is currently undergoing trials under commercial conditions.
Laboratory Personnel
Janisiewicz Laboratory Publications
Google Scholar https://scholar.google.com/citations?hl=en
Current Projects
Biological control of postharvest
diseases We developed a biocontrol system on apples and
pears which resulted in the first commercial product, BioSave® (Jet Harvest Solution,
FL), based on a bacterial antagonist for controlling postharvest diseases of
fruits. The commercial use of BioSave® has been increasing steadily since Observations
of resistance to postharvest apple decays are limited because breeders
generally evaluate un-infected fruit for fruit quality and yield. This may
reflect the general belief that little resistance or variation in
resistance against postharvest decays exists in the apple gene pool currently
used in breeding programs, the lack of awareness of the significant Phenolic analysis: A = ‘Golden Delicious’, B =
Susceptible wild apple, C, D, E = Resistant wild apple We evaluated
the “Kazak” germplasm collection for resistance to postharvest blue mold and
bitter rot decays and found greater diversity among the “Kazak” apple
collection than among cultivated apples as evidenced by their broad range of fruit
maturity dates, quality, and disease resistance patterns. We found immune and resistant apple
accessions that may serve as a genetic source of resistance in breeding
programs. Most of our current research is focused on explaining the mechanism
of resistance to blue mold and bitter rot in those apple and developing physiological
(phenolic substances) and genetic markers that could be used by breeders to
select resistant crosses. UV-C/dark – antagonist treatment to
control strawberry diseases
The battle against postharvest decays of fruits and vegetables has been
fought for decades but has not yet been won. Even the average consumer, who
shops for quality fresh fruits and vegetables and must often discard spoiled
produce, recognizes the persistent problem of postharvest decay. Although the
development of modern fungicides and improved storage technologies in the 1960s
and 1970s have greatly extended the shelf life of fruit after harvest, significant
postharvest losses that vary from an estimated 5 percent to more than 20
percent depending on the commodity, still accrue in the United States. The postharvest
use of fungicides has been increasingly curtailed by the development of
pathogen resistance to many key fungicides, the lack of replacement fungicides,
and public perception that pesticides are harmful to human health and the
environment. This negative perception has promoted governmental policies
restricting the use of fungicides and necessitated the development of
alternative treatments.
its large scale
introduction in 1996 and has been expanded to cherries, potatoes and sweet
potatoes. The concept of searching for antagonists against postharvest decays
of fruits among the natural microflora of fruit has resulted in finding the
most effective bacterial and yeast antagonists. Our current research includes the
continuation of the characterization of the microbiota of pome and stone fruits
and its use to control postharvest fruit decays, including those originating
from latent infections in the orchard. Several
bacterial and yeast antagonist effective against Monilinia
fructicola, the fungus that causes brown rot of stone fruits, have been found.
These antagonists can colonize various fungal structures including appressoria
and fungal hyphae, and can control brown rot under favorable conditions. The potential
usefulness of these antagonists is the subject of current studies in the orchard
and after harvest. 
Blue mold and bitter rot resistance
in wild apples
losses caused by postharvest decays, or the belief that fungicides can
take care of the problem. Wild apple forest stands of Malus sieversii with great diversity representing a much broader
genetic pool of important horticultural traits than the domesticated apples
currently used in breeding program still exist in Kazakhstan today, the center
of origin of domesticated apple. Several USDA expeditions aimed at collecting
this germplasm were made in the 1990s resulting in the ‘‘Kazak’’ collection of germplasm
clones and seedlings maintained at the USDA/Cornell/NYS Agricultural Research
Station in Geneva, NY.
As much as 80% of postharvest decays of strawberries originate from flower
infections. Application of fungicides to strawberry plants from bloom
throughout the growing season in 7-10 day intervals creates strong fungicide
resistance selection pressure resulting in wide spread development of
resistance to major fungicides. Recently, high levels of resistance to
pyraclostrobin, fenhexamid, and boscalid, the major fungicides used in
strawberry production, have been recently detected. Some fungal isolates had
double or even triple-resistance to these fungicides. Additional effective
control practices are urgently needed to maintain current levels of strawberry
production. 
We developed a new technology using a specific UV-C/dark treatment combined
with the application of biocontrol agents to control gray mold, anthracnose and
powdery mildew, especially in protective culture where the use of fungicides is
restricted or prohibited. By applying
UV-C irradiation at night followed by a specific dark period, s the microbial
killing power of UV-C increase by six to ten-fold, depending on the pathogen. The
dark period prevents induction of the repair mechanism (requiring light to
function) of microbial DNA which is damaged by UV-C irradiation.
Since the UV-C/dark treatment is non-discriminatory and kills other
microbes in addition to the plant pathogens, we apply beneficial microbes to
the plants after the UV-C treatment to fill the “microbial vacuum”. We also study the effect of the treatment on
changes in organoleptic and chemical qualities of fruit, and the microbial
safety through microbiome analysis. 
