Germplasm Evaluation for the Incidence of Fungal Spot and Cracking Prevalence in the Fruit of Pawpaw [ Asimina Triloba(L.) Dunal]

Abstract

Fungal lesions have been observed on the fruit surface of many pawpaw [Asimina triloba(L.) Dunal] cultivars and consist of a complex of three fungi, Mycocentrospora asiminaeEllis & Kellerm., Rhopaloconidium asiminaeEllis and Morg, and Phyllosticta asiminaeEllis and Kellerm. Pawpaw fruit occasionally exhibit cracking, and field observations suggest cracking may vary by cultivar and be related to infection by this fungal complex. The objective of this study was to determine if fungal lesions and cracking incidence varied by cultivar or advanced selection, and if there was a correlation between fruit lesion occurrence and fruit cracking. Ripe fruit were harvested three times per week from a mature pawpaw planting consisting of ten pawpaw cultivars and advanced selections ['Sunflower' (control), G4-25, G5-23, G6-120, G9-111, Haz-1, Haz-2, Hi 4-1, Hi 7-5, and NC-1]. Percent coverage by fungal lesion was visually estimated, and fruit cracking was evaluated for each fruit harvested. Fruit weight, size of disease lesion, and cracking all varied significantly by cultivar. Overall, the genotypes G4-25, G5-23, G6-120, and Haz-2 displayed less than 10% fungal lesion of fruit in 2012 and 2013. A positive correlation was found between cracking and fungal lesion as well as fruit weight and cracking. However, other factors could also be related to fruit cracking, such as genotype and environment. Future studies are needed to determine the relationship between fruit lesions and fruit cracking in pawpaw, and to determine varietal resistance to these fungi and possible control measures.