I'm very impressed by the variety of plums you grow. It would be nice if you gave us all evaluations of your favorite 15 or 20 varieties in terms of flavor and productivity.

I find that prune plums in general don't crack as much as Jap types and some of the gage Euros.

Shiro is a huge cracker here when rain comes just as it ripens but I manage some trees not in full sun. It is less a problem where it is in full sun- especially on windy sites.

Of Jap types, Santa Rosa and it's close relatives are very crack resistant. I suggest you try Earli Majic from Hilltop, which is the best I've tried in its early season of Jap types and like other SR types doesn't crack much. Fortune is highly susceptible and Elephant Heart also. Elephant H. also gets a lot of something called pitch pockets which is a large problem for me. Too bad because they're both so good tasting I can't cut the trees down.

You also have to grow Satsuma (ACN) which has some of that Elephant Heart quality with none of the problems. Did I mention that EH is also slow to come into bearing for a Jap? Satsuma is very precocious, productive and crack-free. Unfortunately it's rather a small plum- much smaller than EH.

Of later prune types I really like Valor (ACN) a lot for good size and great flavor but may not work so well for commercial production because of an extremely long ripening period.

Most commercial growers solve a lot of the cracking problem by picking their plums before they're any good as a lot of the cracking happens just as they sweeten up.

I don't think you can do much better than a scale like this. Even with such a scale, it varies from climate to climate so your scale is accurate for you only. My Superiors for example ripen up softer than yours I expect since its hotter, and they have yet to crack. There does seem to be some commonality, for example my La Crescent is somewhat prone to cracking and my Coes Golden Drop and French Prune are medium-low for me which is where the related Euro plums are on your scale.

I would also be interested in which plums you like the best. I have a couple dozen plums I am trying and so far only Satsuma is on my winner list for reliably producing great plums every year, even if a bit on the small side.

Scott

That's pretty normal that soft plums crack easier then late
firm prune plums, allot of rain can do it too.
GreenGage or Reine De Claude Gage is the same plum.

Konrad

One of the firmest J. plums I grow, probably the firmest, is Fortune and it cracked terribly the year before last under very wet conditions. Softness doesn't seem to be an issue for the J. types and I can't say I've seen a correlation with the Euros either. Most plums are picked soft. I don't know that I pick gages softer than prune types. I have far less experience with gages though.

Plumhillfarm, I am a plum collector and will be going out to the CRFG scion exchanges next week, most of my 15 trees are starting to produce. Dozens of grafts (including many on your list) should produce this next season. Shiro cracks badly for my small tree. On your list, Shiro has low tendency to crack. But, there are cultivars that do crack up to 100%. Many Pluots I grow are crackers even when they are grown in California. Superior unfortunately cracks a lot here. I occasionally get even a few peaches that crack but these are thinned, like nothing. I also find the same tree performs different on the more shaded side of my yard. This year there was a lot less cracking but a tendency towards dry taste. I think there are cultural practices we may learn to reduce cracking to acceptable levels. My plums tended to crack less as the tree matures. This winter I covered the entire plum area with wood chips to keep the soil moisture constant. So generally a cracking list would only be a guideline. ACN grows and sells a full line of pluots and some plums that are crackers. Possibly they know more than we do.

Thanks for the responses.

As for cracking, it seems not to depend so much on the firmness of the outside, but the amount of sugar on the inside. Pembina (and a bunch of others especially the American-Japanese hybrids) ripen from the inside out, being firm on the outside and soft in the center. When they crack they open up like a flower showing the pit. The trick is to pick them as soon as the center starts to soften, before to much sugar is released (the sugar causes an increase in pressure if water is present). We do this by tasting as we go, but still loose a lot of fruit.

As for the best variety, the question we deal with is "What is the best today". We are setup up for sequential ripening with over 70 plum varieties, 6 or so peaches, and sweet and sour cherries (we have a couple of apricots which produce a crop every 3 years or so, could use more if they cropped regularily). The cherries start in the middle of July and the rest start at the beginning of August and last until the middle of Oct, so we need a "favorite" every week for 12 weeks.

The favorite of our customers by far is Purple Heart, medium sized Japanese which is purple all the way thru with outstanding flavor. It requires multiple picking over a couple of weeks but stores very well for a Japanese.

Other favorites include:
American Mirabelle, which ripens at the beginning of Sept and is extremely sweet and flavorible
Royal De Vilvoorde medium small european,
Kirkes Blue, blue European with very sweet green flesh
Catherine, late yellow European
De Montford, Early European
Oullins gage a large sweet gage and productive
Alabaster, medium sized yellow European
Empress and Fellenburg (from millers), very rich and sweet
Opal, Small early European
Early Costello, early purple Japanese ripens just after methley with much better flavor
Rose Marie, very good late Japanese large purple with purple-red steaks (may be mis-identified, I got it as scionwood from a private party)
Formosa, very large very good japanese, marginally hardy, fruits every couple of years
Great Yellow, large yellow very good plum, productive, Burbank selection
Superior good, but cracks
Ozark Premier, Large Japanese, marginally hardy but normally crops, must be picked while hard or turns to mush

These are the favorites, but most of the others are very good when picked at peak ripeness which is what we do. There is a good deal of waste (which I plan on turning into brandy after I retire from my day job).

Please let me know your favorites as well.

We need better early varieties, I have a 2nd yr Early Gold which has not fruited yet, and ordered some Oushi wase for this spring. We have Methley, Comet de Kumetz(sp?), Early Costello for early plums

I could not find anyone selling Early Magic (Hilltop does not list it). Would it be possible to get some scionwood?

I have a couple of 2nd yr Satsuma�s (and Marisopal� as well) which had 2 plums on them last year, should get more this year. We tried Santa Rosa, but they were not hardy enough (couple of crops then died)

As for the gages, our green gage (gurney�s) is significantly different than our Riene De Claude gage (grin). I am sure there are many strains out there. Both are not very productive, and if they don�t put out a good crop this year I will pull them out.

On the older varieties, like Fellenburg, the specific strain may be important, I have read that Valor is significantly sweeter than Fellenburg, but its hard to believe since the variety we have is so sweet its like honey.

Eric

70 varieties, I think you have all of us beat there. I agree on the Purple Heart, I have a young tree and had to harvest early last summer to get the few fruits before the birds (they know good fruit, all the PHs were getting nailed and they were ignoring the others nearby) but even underripe they were better than most of my other plums. Here are some other ones I am liking although some have flaws.

French Prune (aka French Petite, French Improved, Prune d'Agen) - a classic prune plum with delicious sugary flavor. Also highly productive. Cracks sometimes. They were quite a bit better than my Fellenberg.

Coe's Golden Drop - A wonderful juicy aromatic plum; unfortunately quite prone to cracking and rot.

Spring Satin - Taste is fine; the main advantage is its very early (not quite spring but late June for me). It may freeze out for you since its a plumcot, but it could be worth a try; its a very easy grower and highly precocious and productive.

Wickson - this plum has a unique rich and aromatic flavor. Its somewhat prone to rot and they also sometimes get those pockets like the EH as mentioned by hman above.

Santa Rosa - one of the best tasting but not productive for me.

Satsuma - as mentioned above, its my favorite. Pick late to get the spicy flavor that makes them stand out.

Flavor Supreme - excellent taste but extremely unproductive.

Superior - a good plum but not always ripening sweet enough for me, maybe its too hot.

Red Heart - Similar but not quite as good as Satsuma; quite a bit later.

Scott

Cultural practices for cracking.

I agree this is important.

Our farm is in the Champlain Valley ~ 1 mile from Lake Champlain. The soil is brown limestone clay with a 6 degree slope to the west. The trees are planted on small raised strips north to south where manure and sand as tilled in to cut the clay a ~ 12X16� centers. There is a 300� wide forest to the south and west, a ridge on the east and just a treed fence line on the north so we are protected from wind except from the north. We have in ground dripper irrigation fed from 2 small ponds but with limited capacity.

Our season is short, Empress, and even Stanley sometimes do not ripen properly before it gets to cold. It�s not that it freezes, but there is to little light and warmth for them to sweeten up

The clay holds water well, so early ripening fruit usually has fairly constant water supply, late July and August is when it normally dries out and the clay cracks. Cracked clay is extremely efficient is trapping any rainfall, as it just runs down the cracks, not off the field. A 20 min thunder shower can provide water for a week. I would like to get a few tons of cheap gypsum to cut the clay some more.

I fertilize 3X yr, May, July, Oct with compost mixed with dry fertilizer (more nitrogen in May and July) to try and get >1� growth on the mature trees.

I prune 25-30% off everything each year, more on the very vigorous stuff.

The trees are kept to 8-10� tall and wide with some exceptions.

We thin to ~6" between fruit, which is likely not enough.

We have some mulched areas between the trees (we have voles so I keep it 3� from the trunks), but we do not have enough chips to do all the trees.

Last year was the first year in 3 yrs we had an extended dry spell. Since I had not used the irrigation system in 2 yrs, it took awhile to get all the leaks fixed. Then we got 2" of rain and had massive cracking with dozens of trees 100% loss.

My First Lesson: make sure your irrigation system works when you need it. It is very likely the damage would have been far less if the trees had not been so dry when the rain hit.

We do get cracked Shiros, but a lot lower % of them than our other varieties. It could be it dry�s out later here, and or the temperatures are more moderate here, or the swings in water stress (combined water and heat) occur later here.

My opinion on cracking is it�s driven by hydrostatic pressure which occurs when the starch gets broken down to sugars, then the sugars absorb water increasing the pressure inside the fruit. Whether it cracks or not is due to how strong the fruit is vs this pressure, and how fast the pressure builds. Dry fruit splits more due to the rapid buildup of pressure as the tree re-hydrates, where as properly hydrated fruits only absorb a limited amount more water so the pressure differences are less when a hydrated fruit is rained on than a dry fruit.

Some fruits have lots of sugar but crack little, like fellenburg, which I put in the fruit strength (or perhaps flexability) bucket.

What do you think?

I would like to find out which varieties are so called "strong"

If you send me you email I will send you a list of what varieties we have and some basic data.

I am interested in scion swapping as well.

Eric

Some observations;

The most cracking in plums comes after rain.

I've put footies on plums to protect them from yellow jackets and those cracked the next day in rain and ones on the same tree without footies didn't crack. So it appears moisture softens the skin enough to crack them.

As plum trees mature I've noticed less cracking.

Things I am trying now;

Spread thick wood chip mulch around entire root area to keep soil moisture constant.

I've had small 'green' plums crack two seasons ago. Sugars haven't developed in small green plums to crack them. Last season they didn't crack but PC got them. The tree has grown a lot larger and maybe a lot less cracking next season.

Allow trees to grow large as possible.

Eric, I could give you some Earli-Majic wood or trade for some Purple Heart. Maybe you can give me some tips on grafting plums as my take rate sucks with them.

I don't understand why Hilltop would stop selling Earli-Majic when it has become a somewhat noticed variety- at least by U of Washington, which included it in a variety evaluation study. It is theirs exclusively, unfortunately.

By the way, I haven't observed a correlation between cracking and uneven moisture through the growing season. As Ace mentioned, my experience is cracking occurs when it rains near picking time. The 09 season was, by far, the worst cracking year I've experienced and the rains were so constant the soil never dried out.

I've not had any cracking without rain within a week of harvest on any variety. I went to a lecture about Rheine Claude production in France and the lecturer said a successful harvest was completely reliant a rain free period the week or two preceding harvest.