The 2009 ASHS Annual Conference

Pawpaw (Asimina triloba) is a tree fruit native to the Eastern U.S. with increasing popularity as a high-value niche crop. Pawpaw fruit sell for $3-4/lb at farmers markets and $5-10/lb via mail order. Two undesirable characteristics of pawpaw are great variation in fruit size and short shelf life, caused in part by a small tear in the skin created when fruit are harvested from the cluster, allowing pathogens to enter the fruit. It is beneficial for growers to produce large, consistently sized fruit to command a premium price and decrease time sorting fruit. Within-cluster thinning of pawpaw to one fruit could increase fruit size and improve shelf-life by allowing the peduncle to be cut at harvest, maintaining an intact epidermis. Four pawpaw cultivars (Mitchell, NC-1, Overleese, and PA-Golden) were utilized in a fruit thinning study at the Kentucky State University research farm over two years. The objective of the study was to determine the effect of hand-thinning on pawpaw fruit size. Treatments were no thinning (control) or hand-thinning all clusters on the tree to one fruit per cluster. Trees were thinned in early June, when fruit were approximately 1.5 cm in length. Fruit were harvested from mid August through late September, and twenty-five fruit per tree were weighed to obtain average fruit weights. Fruit from hand-thinned trees weighed significantly more than those from control trees (47% and 23% greater weight in 2006 and 2008, respectively). Pawpaw, like many other tree fruits, benefits from fruit thinning to reduce crop load in order to increase fruit size.