Any SCAB resistance in the following MN varieties?? Frostbite Haralred...

Asked March 8, 2015, 4:06 AM EDT

Any SCAB resistance in the following MN varieties?? Frostbite Haralred (Haralson sport) Keepsake NW Greening Kerr applecrab (technically a Morden, MB creation, but it is Haralson x Dolgo).

Whitman County Washington apples fruit trees apple scab horticulture

3 Responses

Thank you for your question. I'm afraid I cannot report any special scab resistance in the varieties that you listed. Keepsake is actually listed as "susceptible" to apple scab.
Many of the Minnesota varieties are known for their tolerance to cold, so if you are looking for cold tolerant apples that are also resistant to apple scab there are a few varities to try. Williams Pride is an early maturing variety listed as apple scab immune. Liberty and Redfree are midseason apples that are also reportedly immune to scab.
I hope this answers your question, and I wish you success with your apples!

Thanks for your prompt reply. I did not get a reply from several MN nurseries which merchandise these varieties. Perhaps they sipping whiskey and while fishing ice holes this time of year even as other Americans are very busy awakening their gardens. Since asking the expert question, however, I discovered this very useful presentation by a PhD at UMN, which was given to an organic society. Was aware Honeycrisp had purported scab resistance. That Zestar! did not. The others appear to be somewhat, so ecological location and cultural habits of the grower would likely influence these one way or the other. ........... So, this presentation confirms in a way your Expert Opinion as to scap susceptibility of MN varieites. SweetSixteen's fireblight issues might be moreso a problem in the early years when this vigorous tree is growing fast. Perhaps a dwarfing rootstock or growing it as an espalier would be a good idea. It tends to want to grow upwards and has some blank wood---trees fruit more if branches are more horizontal. So, espalier or weight/tie the branches. (Dr. Terence Robinson of Cornell has some excellent videos on Youtube about this. Jon Clemens of UMass has some great videos too.) ....... Keepsake and Haralson tend towards either biennialism or small fruits from over-cropping. Perhaps espalier when be best in order to make easy of fruit thinning and produce larger fruits. Wish that the UMN professor's presentation *link above) mentioned NW Greening. I have seen some reports of it being similar to other MN varieites regarding scab. However, the following gentleman, who might be located in NE Canada, raves over the tree: More generall as regarding resistances -- a Purdue professor now calls into question the famed Malus Floribunda, whose genes are often touted as conveying scab resistance to apple trees. She says longer term field studies and pathogen evolution considerations change our views of many apple trees: Purdue is very impressive in how they communicate detailed useful information to the American public. They are superior to UMN in this regard (not withstanding the assistance given by the UMN professor in the link above). It is that the UMN website provides content that makes you want to eat the apple, but it does not provide critical information about the tree itself. Whereas Purdue talks to everybody like they are intelligent, hardworking and curiously minded adults who are serious about educating themselves and growing trees: is good, but they currently have the parentage incorrect for SweetSixteen and Keepsake. And they fail to list Frostbite, which is a parent of both of these MN varieites. Some of their information elsewhere I find a bit suspect, though not as much as other sites. E.g., Antonovka might be much stronger against scab than they report. Also, they list Liberty as a triploid and many other sites have it as a diploid. Recently, I believe, Liberty was genetically tested, but somehow nobody seems to agree about its ploidity. . . . Apple scientists are a lot like economists and disagree about everything. I would caution on the USDA site. It is full of typos and some questionable data. Its Narrative on Wickson applecrab is outrageously incorrect. It says it is a awful tasting apple, when everyone rates it tops and for its 25 BRIX. USDA lists diametrically opposed fireblight rating on St. Edmunds Pippin and St. Edmunds Russet (which are the same apple tree, but by UK v. US names -- even their entry pages indicate one entry is a duplicate of the other, because they are synoymous). And there are many other examples of problems with the site, which is not surprising since bureaucracies'are notoriously inept. Undoubtedly a failure in apple information is when people do not indicate the ecological location where the data was gathered. The world is huge and also the US is a large country with many ecologies. It is very different to grow apple trees in Southern California vs Idaho. Not indicating ecological location makes the data almost worthless. It would be like a realtor not mentioning the city in the property listing. And yet even many professors fail this way. How can they be called scientists when they fail the most basic empirical details. What the beginner can do is review many, many different opinions and try to develop a synthesis. Caution: many sites simply cut&paste or paraphrase what others have posted. It is astonishing that nurseries who apparently grow the trees, do not simply report on their experience. .... Notice how few photos there are available of the apple tree varieites. This is astonishing given this day and age of selfies. Vigor. The following useful website gives tree vigor for 1000s of varieites. People should consider vigor when choosing rootstock. A Bramley Seedling is T3. A Haralson is a T1. A Bramley on a M27 ultra-dwarfing stock might look like a Haralson on a Geneva 11 or even a M26 or M7 -- depending on soil, water and light and other ecology. ---

You have done an excellent job of summarizing the information available and also recommending some very useful websites. Thank you!