Skip to main content
ARS Home » Northeast Area » Kearneysville, West Virginia » Appalachian Fruit Research Laboratory » Innovative Fruit Production, Improvement, and Protection » People » Wojciech Janisiewicz

Wojciech J Janisiewicz

Research Plant Pathologist


/ARSUserFiles/80800505/J. Wojciech/profile.jpg

Dr. Wojciech J. Janisiewicz
Innovative Fruit Production, Improvement and Protection
Research Plant Pathologist
Phone: (304) 725-3451 ext. 358
Fax: (304) 728-7232
Room 333



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.



1984 to Present

Research Plant Pathologist, USDA, ARS, Appalachian Fruit Research Station, Kearneysville, WV

1983 September - December

Temporary Appointment, Tree Fruit Research Center, Washington State University, Wenatchee, WA, Postharvest Pathology, Collaborative research with Stemilt Storage

1977 April - September

Laboratory Technician, Tree Fruit Research Station, Washington State University, Wenatchee, WA

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

Breyn Nichols

Janisiewicz Laboratory Publications

Google Scholar

Current Projects

Biological control of postharvest 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.

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

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

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 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.

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

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.