===== PAGE 1 ===== ## Kentucky State University Pawpaw Grafting Update
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### Sheri Crabtree and Dr. Kirk Pomper KSU Land Grant Program ===== PAGE 2 ===== Pawpaw has great potential as a new alternative fruit crop for limited resource farmers
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Pawpaw cultivars are generally propagated by chip-budding the desired variety onto a seedling rootstock Zimmerman
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===== PAGE 3 ===== Leaving 6-8 leaves on the rootstock seedling when chip-budding pawpaw may increase bud take and scion growth The remaining rootstock leaves will provide energy for the developing scion bud, until the bud has initiated leaves and is able to photosynthesize and support its own growth After approximately 6 weeks, the rootstock's leaves would be pruned away, leaving the new scion shoot ===== PAGE 4 ===== The objective of this study was to determine if leaving 6-8 leaves on pawpaw seedling rootstocks for 6 weeks will enhance scion bud break and growth The experiment consisted of: 2 pawpaw scions (Sunflower and Susquehanna) 2 seedling rootstocks (Sunflower and K8-2) 2 leaf treatments (removing all leaves at time of grafting vs leaving 6-8 leaves on the grafted tree) ===== PAGE 5 ===== Dormant budwood was grafted onto actively growing 1 year old seedlings in the greenhouse in June 2006 Data was collected weekly on scion budbreak and leaf number Rootstock shoots were removed after 6 weeks
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===== PAGE 6 =====
Pawpaw graft take percentage before being cut back - 8/25/06Pawpaw graft take percentage after being cut back - 9/22/06
ScionScion
Sun59%SunCEO
Sus70%SusImage
sig.Imagesig.
RSRS
8-2Image8-2Image
SunSun
sig.sig.
LeavesLeaves
LImageLImage
NLNL
sig.sig.
Blocks (date grafted)Blocks (date grafted)
21-Jun53.0%21-Jun64% cd
22-Jun69.0%22-Jun69% bcd
23-Jun67.0%23-Jun69% bcd
26-Jun64.0%26-Jun83% ab
27-Jun56.0%27-Jun58% d
28-Jun78.0%28-Jun81% abc
2-Jul67.0%2-Jul100% a
sigNSsig*
===== PAGE 7 =====
Number of leaves on chip budded pawpaw scions 8/22/06Number of leaves on chip budded pawpaw scions 9/25/06
[F4]Scion
ImageImageSunImage
Sus
sig.
Image6.1RS
Image8-2Image
Sun
sig.
ImageImageLeaves
LImage
NL
sig.
Blocks (date grafted)Blocks (date grafted)
21-Jun7.2 a21-Jun6.1 bc
22-Jun6.7 a22-Jun7.8 ab
23-Jun7.0 a23-Jun8.0 a
26-Jun6.5 a26-Jun6.9 ab
27-Jun6.2 ab27-Jun7.8 ab
28-Jun5.3 b28-Jun7.4 ab
2-Jul2.8 c2-Jul4.1 c
sig.**sig.**
===== PAGE 8 ===== ■ Scion cultivar did not affect chip bud take or scion leaf number Chip buds on K8-2 rootstock had a higher percentage take than those budded onto Sunflower rootstock. There was not a significant difference in scion leaf number between rootstocks ===== PAGE 9 ===== Chip-budded pawpaws with leaves remaining on the rootstock seedling had a higher percentage bud take than chip-budded pawpaws on which the rootstock's leaves had been removed when budded Budded pawpaw trees which had the rootstock's leaves removed when grafted had more scion leaves than trees on which rootstock leaves were retained for 6 weeks after grafting ===== PAGE 10 ===== ## Conclusions While rootstock leaf retention was beneficial for graft union development, the resulting scions actually had fewer leaves. Pawpaw chip-bud emergence improves by leaving 6-8 leaves on the rootstock to support the scion budbreak and growth. These leaves should be removed after 6 weeks to encourage scion growth. ===== PAGE 11 ===== ## Take-home message When chip-budding pawpaw, leave 6-8 leaves on the rootstock shoot to support scion growth Remove these leaves 6 weeks after scion bud emerges to improve scion growth ===== PAGE 12 ===== ## Questions? Sheri Crabtree (502) 597-6375 sheri.crabtree@kysu.edu Dr. Kirk Pomper: (502) 597-5942 kirk.pomper@kysu.edu Pawpaw Information Website: www.pawpaw.kysu.edu