North American Fruit Explorers mailing list at ibiblio

[DavidU9999@aol.com]

I have a few thoughts to share with those who have been responding to Charles 
Paradise who wrote:
"I recommend planting at least a dozen varieties [of plums].  I believe you 
need to create many different sources of pollen, in order to realize fruit 
set.  Your choice in my opinion is whether to cut down your shiro and santa 
rosa Japanese plums and plant something more reliably fruitful, or else to 
consider yourself committed and add many more varieties, and plant them 
closely together.

Think plum thicket.  Notice the ''thick'' in the word ''thicket.''
 
The Japanese-American hybrids can be hard to cross pollinate and Charles is 
right that lots of varieties help with fruit set on the Japanese plums also.  
Santa Rosa and a few others are supposed to be self-fruitful, but have better 
yields with cross pollination.  If you don't have lots of room to plant, 
consider planting 3 or 4 trees in one hole.  I like that better than grafting 
several trees on one root.  Best to pick varieties with similar growth rates, 
if possible, and use the same rootstock for all in that hole.

Del Stubbs writes: "My plum grafting luck onto p. americana has been nearly a 
zero. For 4 years I have been trying both spring W&T grafting of dormant 
scions ( both bench and in the field) , and late august bud grafting. So far 
I have only one that  has grafted successfully...bud graft of  Alderman  on 
p. americana."

Del, I have no experience with P americana as a rootstock, but it should do 
well under the hybrids.  Were these well established roots in pots or 
recently dug when you bench grafted them?  I have grafted Waneta, Gracious, 
Hanska, and a couple others in the past on Myrobalan with good luck.  Best 
rootstocks for plums in my opinion are Myrobalan and Myro 29C; peach, if your 
soil conditions and climate permit; Marianna 2624; and the St Julian A 
clones.  I liked Pixie in the past but don't know a source now.  I'm trying 
Brompton plum this year and have had very good takes and early growth on 
several European (P. domestica) cultivars.

Lucky Pittman writes: "I'm hardly anything more than a novice with 
stonefruits - and I've virtually abandoned all of them that I currently have 
planted - I'm just 
waiting on the borers to take 'em out so I can replace them with pears or 
persimmons - but I have grafted a few, with reasonable success.
I've done simple whips or W&T of dormant scions of both Euro & Jap hybrid 
plums onto native plum(P.angustifolia?), P.americana, and Nanking 
cherry(P.tomentosa) with good results - after the rootstocks had fully leafed.
I've done summer budding of peaches and Jap.hybrid plums onto both 
P.americana and P.tomentosa."

Lucky, I'm sure you are more than a novice grafting.  I remember T.O. Warren 
telling me not to use P. angustifolia (Chickasaw plum) as a rootstock but I 
know others that use it.  If you can find a clone that doesn't sucker too 
badly, it probably would be ok.

Chris Mauchline writes:  I don't consider myself an "expert" on plum 
grafting, but I have gathered some experience over the past few years.  I 
don't have experience w/ P. americana or the cold-hardy plum-hybrids you are 
using.  Plums (and all prunus (it seems) to varying degrees) require heat to 
callus properly between stock and scion.  I attended an apricot workshop as 
part of the apricot interest group.  I grafted 4 European plums, 2 hybrids (a 
plumcot and a peachcot) and 2 apricots.  I later grafted another 2 apricots 
and another European plum.  I have never been previously successful bench 
grafting plums (or any prunus) before, but I have successfully field grafted 
apricot, plum (1 European and 2 Japanese), and cherry (4 times).  

Chris, You are absolutely correct about needing heat to callous.  I have 
found that apricot is the most critical with peach about as bad.  Plum is the 
least fussy of the stone fruit, in my experience. I normally graft plums 
after I have finished grafting apples and pears as they probably do need a 
little more heat than Pyrus.  I also wait to graft apricot - usually late 
March here or bench graft earlier and place in a heated propagation box.

"I'd say roughly (including past years) that I'm batting around 40% on 
apricot and 80-90% on plums."

If you are getting just 40% something is wrong.  What rootstock are you 
using?  I use Manchurian apricot seedlings, Myrobalan plum, and peach.  Seems 
that the apricot seedlings do the best.  A good time to graft is when buds 
are just beginning to grow.

"I have had success in prior years field grafting (after leaf  break), but 
covering the graft with a plastic bag (to retain moisture/heat), and then 
covering that with a paper bag w/ corners removed (to keep the graft from 
getting too hot).  This year I also tried simply covering the whole scion w/ 
parafilm and that seems equally successful."

As long as you have dormant scions, go ahead and try to graft them. I'm going 
to graft some misses today. When you graft late, you need to take extra care 
to prevent drying of the scions as Chris says.  That is the method that I use 
to graft persimmons and I usually wait until early May here as we are rather 
cool here in Sebastopol.

I learned to graft from the master T.O. Warren, who until recently was the 
grafting consultant for NAFEX.  He taught me to use masking tape only, but I 
often use poly tape, also, for extra insurance if I'm not completely happy 
about my carpentry. I love Parafilm.  When I do a cleft graft, I wrap the 
masking tape and the tip of the scion with parafilm.   I have never thought 
grafting wax necessary and it's a real bother. 

"My problem this year: grafting (besides 10 stitches): I grafted Puget Gold 
apricot 3 times this year.  Bench grafted it to St. Julian A once, Mariana 
2624 once, and field grafted it to an existing tree once."

"The St. J is failed, and the jury is still out on the other two, but they 
are looking less and less likely.  Does anyone know if P.G. is particularly 
hard to graft?"

Chris, did you get the wood from Bob Purvis?  I sent Bob a big package of 
Puget Gold wood in mid Feb.  My tree died this spring, most likely from 
bacterial canker.  Maybe the wood I sent wasn't any good.  I haven't heard 
that Puget Gold is hard to graft.

Got to go graft those misses.  Anyone interested in reviving the plum 
interest group?

David Ulmer - Southern Plum Interest Group
Sebastopol. CA
Zone 9 (but cool summers)