Here is a draft list of attributes I plan to gather for Pawpaw cultivars available from U.S. retailers. Are there any you’d like to see added?
This is a compatible MS Word document loaded into Google Drive. Anyone on the internet with the link can view it.
Looks like a pretty thorough list! One thing I’d like to see is GDD to fruit maturity. For us folks on the northern end of things, a couple hundred degree-days could make all the difference.
Jay,
Thank you for the input. I almost included all the parameters needed to calculate GDD but left out the observation year. I’ve just added it. 
Hi Richard,
I am curious about health concerns with Annonacin. I have read that some think the research on nervous system by this compound is not well documented or trustworthy, so it’s difficult for people to make informed decisions about how much can be safely consumed. So while it may be some time before more reliable medical research is available, I would be interested to know if you could show the % Annonacin as it may vary by variety. Or perhaps the % Annonacin could vary by climate zone more than by variety? I appreciate your efforts as I have been increasing my varieties and this year even growing some from seed to plant along some of our streams here in the Pacific NW.
Thanks
Dennis
Kent, wa
BTW, there are several publications from pharmaceutical researchers regarding annonacin dosage effects and limitations. For some forms of cancers the microencapsulated drug is injected into cancer cell masses to kill cancer cells. These injections purposely kill some of the surrounding cells as would a surgeons knife. In a few of the papers they discuss expected rates of drug escape from the injected area(s) into the patient’s blood stream along with risk factors for human exposure via the blood stream. A major consideration is that the human blood-brain barrier does not filter annonacin - although the risk is slightly less for native peoples of the Americas. From the expected escape rates and risk factors a lifetime injected dosage quantity for one manufacturer’s drug was set at 90mg. This was 20 years ago and might have changed. The bottom line is that the lifetime dosage x the escape rate gives a lower bound on acceptable consumption from annonacin in fruit. My conclusion (and my neighbor at the time, a neuroscientist) was that the known concentrations in cherimoya, custard apple, soursop, etc. were too high a risk. I look forward to determining the concentrations in Pawpaw.
Here’s 4 skin and pulp colors computed from CIE color coordinates published in this paper:
Brannan, R.G., T. Peters, and S.T. Talcott. 2015. Phytochemical analysis of ten varieties of pawpaw (Asimina triloba [L.] Dunal) fruit pulp. Food Chemistry 168:656-661. doi: https://doi.org/10.1016/j.foodchem.2014.07.018.
Do you know of any laboratories that might be able to do this testing? I’m sure many growers on this website would gladly contribute both $$ and samples to such an effort.
Yes, there are many. And as long as samples are being sent to a lab, one might as well be thorough and check for concentrations of several compounds. I’ve been gathering a list from various sources and so far found:
annonacins
carbohydrates
fruit brix
flavonoids
glutamates
phenols
proteins
This year I contracted with a leading genomics lab to obtain high-end whole genome sequencing of 15 Fig cultivars selected for their morphologic attributes. Prior to the contract, many folks on the OurFigs board expressed interest in contributing financially. I decided that not all the offers could be taken seriously, so I first paid for the lab work (it is underway) and then advertised a GoFundMe page. So far I’ve raised $600 of the $101,600 cost plus received several public personal attacks and criticisms of the contract price from some members of OurFigs. Apparently their original offers of help were for boasting 
.
Ah yes, that’s almost an order of magnitude more than I was imagining it would cost. That kind of money is probably going to be hard to raise from hobbyists!
Current total laboratory costs for the list I have above range from $400 to $750. At the lower end some of the items do not include a breakdown of components, i.e. it is standard mass spectrometry results. So for 100 specimens I’m estimating lab costs of $40k to $75k for that portion of the project.
Now in the collection of fruit I’d also like to collect leaf samples from the very same tree and ship them refrigerated overnight to a genetics lab for recording 71 RAPD markers per sample. That lab cost is currently another $40k.
Then the logistics of all this work will run about $10k each for shipping leaf samples and fruit, plus another $10k for travel. So at a lower bound the total looks like $110k.
By then I might have enough horticulture publications that I could partner with a university professor and together we could obtain grant funding.
Hello Richard,
There is a recent topic about growing seedlings in a greenhouse,It reminded me,during previous discussions,about young Pawpaw plants needing to be out of direct sunlight for a year or two.
It looks like your research is aimed at breeding plants,which will produce better fruit.
I’m not sure if eliminating that characteristic(light sensitivity),fits in your plans or is even possible.
I’ve read several reports from various sources that include success / failure rates for propagation by seed. The critical factor is stratification of seed for several weeks in particular soil types and temperature range. The seedlings are then raised outdoors year-round in partial shade. So far I haven’t come across any mention of total shade. These reports are from publications of Northern Nut Growers, American Pomological Society, and the USDA - but of course there are many I haven’t read. There is also this publication of historical interest:
Little 1905 - The Pawpaw.pdf (578.2 KB)
Happen to know what the soil types are and temperature?I’ve always stratified them in damp peat moss,in a baggie,inside a refrigerator’s crisper and have had good success rates.
Thanks for the publication.It’d be cool if some of the author’s plantings were still around.
@Bradybb
See Propagation - Seed on this page:
https://www.ars.usda.gov/pacific-west-area/corvallis-or/national-clonal-germplasm-repository/docs/ncgr-corvallis-asimina-germplasm/#seed
The optimum germination temperatures between 84 and nearly 90 degrees Fahrenheit are higher than I’ve been using. Thank you @Richard for that information. I’ve had approximately 50% germination success using lower temperatures, and otherwise following the procedures outlined in the above link.
It took awhile, but I tracked the propagation reference in the USDA web page down to this reference manual:
Title: Seeds of Woody Plants in North America
Author: Young, James A.; Young, Cheryl G.
Pages: 407
ISBN: 9780931146213
@jcguarneri
I came across this 2008 GDD data from KSU. Perhaps you’ve seen it before?
| Cultivars in retail circulation | Estimated peak flowering week at KSU sites | GDD at KSU sites | Peak harvest week at KSU sites |
|---|---|---|---|
| PA-Golden | 16 | 2499 | 36 |
| Wabash | 16 | 2572 | 36 |
| Rappahannock | 16 | 2586 | 36 |
| NC-1 | 16 | 2620 | 37 |
| Overleese | 16 | 2637 | 37 |
| Taytwo | 16 | 2648 | 37 |
| Taylor | 16 | 2676 | 37 |
| Shenandoah | 16 | 2697 | 37 |
| Susquehanna | 16 | 2703 | 37 |
| Potomac | 16 | 2720 | 37 |
| Mitchell | 16 | 2736 | 37 |
| Sunflower | 16 | 2737 | 37 |
| Wells | 15 | 2751 | 37 |
| 8-20 | 15 | 2753 | 37 |
Thanks.At about $50 a copy,maybe I’ll check if a library has one,first.
Thanks! I’ve at least seen a similar dataset, but more complete info on different cultivars would be amazing. With so much emphasis on hardiness zones, there’s not a lot of info on where pawpaws will actually ripen (especially least not on retail sites!). So having a more complete dataset would be very helpful for choosing regionally appropriate varieties.