Cranberry Fruit Rot Biology and Management

Re-investigation of a New Old Disease: False Blossom

Funded: Wisconsin Cranberry Board 
Co-investigator: Dr. Christelle Guédot, Dept. of Entomology 
The cranberry false blossom phytoplasma and blunt-nosed leafhopper are re-emerging pests in Wisconsin cranberry marshes. The source and spread of these pests have not been confirmed in Wisconsin and pose a threat to the cranberry industry. The objectives of this research will investigate the 1) distribution of cranberry false blossom in Wisconsin cranberry marshes and the molecular identification of the phytoplasma, and 2) distribution and diversity of the leafhopper populations in cranberry.  

Evaluation of heat treatments on cranberry fruit rot pathogen survival and cranberry plant viability

Funded: Wisconsin Specialty Crop Block Grant Program
Cranberry fruit rot (CFR), a complex of at least 12 different species of fungi, can result in reduced fruit quality in Wisconsin marshes. Current management practices of well-timed fungicide applications are effective at reducing disease incidence, however due to the endophytic nature of the fruit rot fungi, many remain in cranberry beds on plant tissues season after season. Possibly exacerbating this situation is the use of cranberry cuttings from established beds to propagate new cranberry beds. If endophytic fungi associated with cranberry fruit rot are present in these symptomless cuttings, this propagation method could introduce CFR pathogens into new plantings. Previous studies demonstrated through fungal isolation from cranberry plants that many CFR pathogens overwinter and survive in the woody tissues and second-year leaves on cranberry uprights. Further, CFR fungi have also been isolated from healthy (symptomless) cranberry flowers and fruits. Currently, these cuttings used for propagation material are not tested or treated for pathogens prior to establishment in new beds. Due to the various factors that influence fruit rot development, it is difficult to know when these endophytic fungi (symptomless infections) develop into fruit rot. Because these factors are difficult to determine and likely vary based on region and pathogen, the best approach to controlling them is preventing their introduction into new plantings. The goals of this research are to develop, assess, and optimize heat treatments of cranberry cuttings to reduce or eliminate fruit rot fungi.