Resistance of diploid Vaccinium spp. to the fruit rot stage of mummy berrydisease

Mummy berry disease caused by Monilinia vaccinii-corymbosi is the most wide spread economically important problem of cultivated blueberry in North Amer ica. In an attempt to identify new sources of resistance to the fruit rot ( mummification) phase of mummy berry, 140 accessions from a total of 21 popu lations from seven wild diploid species of blueberry were evaluated for res istance under greenhouse conditions. Six isolates of M. vaccinii-corymbosi from three states were used as inoculum. A highly resistant response to mum my berry fruit rot was exhibited by all accessions of Vaccinium boreale, V. myrtilloides, V. pallidum, and V. tenellum, and by most accessions of V. d arrowi. Most of the V. corymbosum and V. elliottii accessions were moderate ly to highly susceptible. Introgression of the resistance found in the wild diploid species into horticulturally desirable cultivars could significant ly improve available resistance.