from 0 to 80,000 ppm. Cuttings treated with 40,000 or 80,000 ppm IBA exhibited necrosis of tissue, but all other treatments rooted at a low level, not exceeding 16% (at 10,000 ppm IBA). However, cuttings from a mature source (5 year old trees) largely failed to root, with only one cutting out of 5100 producing one root (at 20,000 ppm IBA). A later unpublished study (Geneve, per comm.) reinforced the role of juvenility in rooting of pawpaw stem cuttings. Stem cuttings taken from 2, 4, 5, and 7 month old pawpaw seedlings were treated with IBA ranging from 0 to 10,000 ppm. Only 6% of cuttings taken from 7 month old seedlings treated with 5000 ppm IBA rooted; no other treatments initiated roots. Cuttings from the 2 month old seedlings produced adventitious roots more readily, ranging from 39% of cuttings not treated with IBA rooting, to 74% of stems treated with 10,000 ppm IBA producing roots. Attempts to root etiolated stem cuttings have also been unsuccessful (Geneve, personal comm).

Studies attempting pawpaw propagation by root cuttings showed that root diameter had a strong effect on shoot production (Finneseth, 1997). No shoots formed on root cuttings with a diameter less than 5 mm; however, 56% of root cuttings with a diameter of 5 mm or greater produced shoots. Unfortunately, currently available cultivars are not available on their own roots, so root cuttings are not a feasible propagation method for current varieties.

Juvenility also has a strong effect on pawpaw bud and shoot development in tissue culture (Finneseth et al., 1997). No explants from mature sources showed bud elongation after 8 weeks in vitro, and the 4% of these explants that survived showed only minimal tissue proliferation after 7 months. In the same study, explants from juvenile pawpaw seedlings responded quickly in culture. Approximately 60% of these explants had expanded axillary buds after only 4 weeks, and by 8 weeks, 100% of these explants had expanded axillary buds, had formed adventitious buds and shoots, and were large enough to subculture. Attempts to root pawpaw microcuttings from 2 year old pawpaw cultures had limited success (Geneve et al., 2003). Limited air layering experiments with pawpaw both in the greenhouse and the field were also unsuccessful (KSU, unpublished data).

Currently, grafting or budding onto a seedling rootstock is the only viable method of clonally propagating pawpaw. Budwood is obtained in March, once the trees' chilling