Pollination
  self-sterile (monoecious)
Blooms
  very late, but terminal buds are still susceptible to frost damage
(in comparison to other species)
Ripens
  4.5 - 6 months
(from the start of the grow season)
pH
  5.5 to 6.5 is preferred. up to 7 may be acceptable for some, but this primarily applies to European chestnuts. a slightly higher pH will often be intolerable.

Native Range and Climate


Chinese chestnuts (Castanea mollissima) are native to East Asia.  The exact region of origin is unknown, but it has been extensively cultivated throughout most of China as well as Korea and Taiwan.  They should be able tolerate a wide range of climates with little trouble, from northern Florida to southern Maine, and all the way to the west coast, provided they are planted in the appropriate soil type.  The primary exception may be the western prairies, such as eastern Colorado, western Kansas, and everything north and south of it.  Wild temperature fluctuations frequently experienced during late winter and early spring may prove to be too harsh on new growth most years.

While certain varieties of the other common chestnut species can thrive in a fairly large range as well, Chinese chestnuts generally exceed their boundaries.  They are consistently the most disease resistant, require the least amount of chill hours to bloom, and have a greater tolerance of cold winters and late frosts than European and Japanese chestnuts.  While the non-dormant terminal buds of Chinese chestnuts are occasionally damaged at the following locations, they appear to avoid frost well enough that a few commercial orchards are grown in states like Iowa, Missouri, Ohio, and northern Florida.  It is "implied" that their buds are most vulnerable around the time late blooming peach are in bloom, but this may not be the most accurate comparison.

American chestnuts (Castanea dentata) are primarily native to the Appalachian region of the United States, from southern Maine to central Mississippi.  The area receives an average of 3" to 5" of rainfall per month, and the average temperature on the hottest day of the year ranges between 80F (26.7C) to 90F (32.2C).  Since they evolved in the eastern half of the United States, they leaf out later than the other common chestnut species, giving them a greater chance to avoid frost damage to their non-dormant buds.[1][2]

Based on limited information, it appears the terminal buds of the Ozark chinquapin (Castanea ozarkensis), a species closely related to the American chestnut — native primarily to the northwestern half of Arkansas, break out close to 1 week after late blooming peaches are around full bloom in southern Missouri.  Until I am able to find more reliable information, I would assume bud break would generally happen around a similar time for the American chestnut and the other (southeastern) American native, the Allegheny chinquapin (Castanea pumila).

European chestnuts (Castanea sativa) are native to scattered parts of Southern Europe, the coastal area of northern Turkey, and the Greater Caucasus Mountains.  Most of the area experiences dry Mediterranean summers, while the Greater Caucasus receives around 2" of rainfall per month.  Additionally, it has naturalized throughout France, parts of Central Europe, and to some extent, England.  The average temperature on the hottest day of the year ranges between 65F to 90F (18.4C to 32.2C), but it generally resides between 75F to 85F (23.9C to 29.4C).

Japanese chestnuts (Castanea crenata), often called Korean chestnuts, are native to Japan and South Korea.  Much of the region receives 3" to 6" of rainfall per month during spring and summer, but a significant area can experience 10" or more for a few months in the middle of the grow season.  The average temperature on the hottest day of the years ranges between 75F to 90F (23.9C to 32.2C) but generally resides near 85F (29.4C).

Bloom and Pollination


Chestnuts produce male and female catkins on the same tree but they are self-sterile.  Pollen production begins very late in the season, roughly 2.5 months after bud break.  Female catkins become receptive a few days later, and they last for one or two weeks.  Pollen from a tree that produces larger nuts may increase the nut size of the tree that is being pollinated (metaxenia).[1] This is not typical for fruits and nuts. 

Some chestnut varieties may bloom heavily a second time during the grow season, but if they are not thinned out (which is generally not done due to the large size of the tree), it may reduce the nut size of the primary crop.[3] In addition, the removal of secondary burrs may allow the tree to produce more primary burrs the following year.  Alternatively, varieties that produce a large number of burrs during the secondary bloom may produce a respectable crop if damage from a late frost prevents the occurrence of the primary bloom.[3]

Unfortunately, information on the secondary bloom is limited, and many of those mentioned happen to be fairly uncommon varieties.  For example, Peach, Qing, Simpson, Carr, AU Homestead, and Gideon produced few secondary burrs, during a three year trial.[3] Armstrong, AU Cropper, Carolina, Crane, Eaton, Ford's Tall, Jersey Gem, Orrin, Mossbarger, Revival, and Willamette produced many secondary burrs.[3]

Disease and Pests


Chestnut blight (Cryphonectria parasitica) is a very serious disease for some Castanea species.  Those that shared a similar native range as the fungus, such as the Chinese and Japanese chestnut, naturally developed resistance to blight, and while there are variations within both species, the Chinese chestnut generally shows a higher degree of resistance.[4] European chestnuts are somewhat susceptible to blight and will eventually die from the disease in certain environments.  Hybrids between C. sativa and an Asian species regularly display some degree of resistance, but often times, it is not enough for them to survive long term.  American chestnuts are highly susceptible and were decimated by blight in the early 1900's, but decades of backcrossing, along with the mollissima genes responsible for blight resistance, has created highly resistant trees that are over 93% American[2] — although they are still quite rare.  Other operations are also taking place, such as genetic modification with a wheat gene responsible for fungal defense[5][6] as well as intercrossing pure American chestnuts that have been found to be less susceptible to blight.[7]

The European chestnut almost suffered a similar fate as the American chestnut, but the lower degree of susceptibility of C. sativa, much like the few American chestnuts that survived in their original form, generally shared another significant quality.  Their death sentence was delayed long enough for a mycovirus to infect the blight, causing it to become hypovirulent, which allowed infected trees to recover.[8] This hypovirus continues to spread naturally in multiple regions within Europe.  In North America, treatment of individual cankers have proven to be successful, but the hypovirus struggles to spread on its own.  This was discovered to primarily be due to blight in the United States being genetically more diverse (having a greater number of vegetative compatibility types that restrict the movement of the hypovirus) than the same fungal species present in Europe.[8]

The lower degree of genetic diversity in Europe may primarily be the direct result of the hypovirus' success.  Tree populations with virus-free blight have been observed to develop a larger number of vegetative compatibility types as the fungus became more established while the number of vc-types in tree populations infected with hypovirulent blight decreased with time.[8]

Varieties that are susceptible are best grown in a dry climate since rain and humidity aid the development and spread of the blight (particularly during spring and summer).[9][10] While chestnut trees tolerate dry climates fairly well, water stress will reduce nut size and yield, and the soil pH in such regions are often too high for chestnuts to survive.  One possible solution, however, is the use of certain oak species, such as Quercus trojana and Quercus coccifera, as a rootstock for alkaline soils since they have been used with some success.[11]

Chestnut trees have a fairly low level of tolerance for clay or other poorly drained soils.  Excessively wet soils will also encourage phytopthora root rot (Phytophthora cinnamomi) on European and American trees (Chinese and Japanese chestnuts have a fairly high degree of resistance).  Phytophthora cambivora is also a problem in Europe, but in the United States, it is rarely mentioned outside of the west coast.  P.  cinnamomi is believed to have eradicated American chestnuts from the lower elevations of the southeast well before the arrival of the chestnut blight, but it did not have a significant effect on the mountainous areas since the pathogen is fairly intolerant of the environment.

Chestnut gall wasp (Dryocosmus kuriphilus) can be a serious problem in regions without natural predators since insecticides have proven to be ineffective.[12][13] Not only do they inhibit shoot growth — reducing leaf and fruit production — but their abandoned galls serve as an entry point for chestnut blight.[14] However, the gall wasp's primary predator, the Torymus sinensis wasp, has been introduced to infested regions throughout the world, and they have become well established.

Several native parasitoids have also learned to exploit the unintentional introduction of the chestnut gall wasp, such as Ormyrus labotus, which can out-compete T.  sinensis in more vegetatively diverse locations, provided there are a significant number of oak trees nearby.[15] This isn't necessarily positive news, since the results of this particular study indicate that only 70% of the galls were parasitized (50% by O.  labotus and 20% by T.  sinensis) rather than ~95% when T.  sinensis was the dominant predator.  It is believed that O.  labotus suppresses the T.  sinensis population by parasitizing their larva in addition to the gall wasp larva.  Fortunately, outside of forest settings, O.  labotus' presence appears to be limited, parasitizing between 0 to 25% of the galls.  This will likely be consistent considering they are a multi-generational species and chestnut trees aren't enough to sustain them throughout the season.[15]

Some varieties are considered to be resistant to the chestnut gall wasp, and in-spite of the uncertainty some appear to have around this claim, it could very well be the case.  Within the first decade after their introduction in 1941, the Japanese discovered multiple C. crenata varieties that were resistant to the gall wasp.[13] One of these varieties, Ginyose, was discovered to produce seedlings that were resistant nearly 100% of the time, even when crossed with a non-resistant variety.  The others produced resistant seedlings roughly 75% of the time.  By 1959, their breeding program named and released three additional resistant varieties selected from a group of over 3,500 seedlings.  They were Tanzawa (Otomune x Taishowase), Ibuki (Ginyose x Toyotamawase), and Tsukuba (Ganna x Hayadama).  Ishizuchi (Ganne x Kasaharawase) was released in 1968.[13]

Shortly after their release, land consisting of chestnut trees dramatically increased, quadrupling from 10,000 to 40,000 hectares within 10 years.[13] However, around this time (1970), a new strain of gall wasp adapted to the resistant trait and began to spread throughout Japan once again.[13] Fortunately, the Japanese discovered and introduced the predatory torymid wasp from China in 1975, with larger populations selected again for introduction in 1979 and 1981.[12] In 1983, 43% of the shoots at their research site were infected, but by 1986, that number had dropped to 14%, far below the tolerable threshold of 30%.  Two years later, it was below 5%, and by 1992, less than 1% of the shoots were infected by the gall wasp,[12] causing interest in resistant varieties to rapidly decline.

Chinquapins from the United States (Castanea pumila and Castanea ozarkensis) are also believed to be resistant to the gall wasp, but, perhaps, to a much greater degree.  In 1995, chinquapin x Asian chestnut hybrids, pollinated by American chestnuts, were planted in North Carolina to determine if the seedlings would carry over gall resistance from their chinquapin ancestry.[16] By 2006, 53 out of 93 were still alive, 36 of which were C. dentata x (C. pumila x C. crenata) and the other 17 of which were C. dentata x (C.  ozarkensis x C. mollissima).  14 out of the 25 C. dentata x (C. pumila x C. crenata) and 7 out of the 9 C. dentata x (C.  ozarkensis x C. mollissima) who showed little to no blight infection had few or no galls present.  Trees that were inflicted with a more severe case of blight were excluding due to the stress possibly making them more attractive to the chestnut gall wasp, however, some of them were free of galls as well.[16]

The most significant pest is the Chestnut weevil. In the US, they primarily make up of two species, the small chestnut weevil and the large chestnut weevil.  The small chestnut weevil (Curculio sayi) is the most common of the two.  They begin to lay their eggs 3 weeks before the nuts ripen (or after the burrs open).  Eggs hatch in 8 to 10 days and the larva feed for 2 or 3 weeks, but cooler temperatures can dramatically delay their development.[17] The larva exit the nut after the nut falls to the ground.  Adult weevils also feed on the nuts.  The damage is insignificant, but it creates an entry point for pathogens that may harm the crop at a later date.

Large chestnut weevils (Curculio caryatrypes) begin laying their eggs 1 or 2 weeks before the small chestnut weevil since their longer snout allows them to gain access to the nut before the burr opens.  Their eggs hatch in only 5 to 7 days.  These advantages allow most of their larva to exit the nut before it falls to the ground, causing them to be more difficult to control, but, as mentioned, they are not as common as the small chestnut weevil.

Sanitation must be practiced if you wish to control the small chestnut weevil's population.  Fallen nuts should be collected within a day or two, before the larva exit the nut.  Afterwards, they should immediately be placed in a hot water bath heated to 120F (49C) for at least 20 minutes.[17] This will kill the eggs and larva without damaging the nut.  If done properly, most of the infected nuts should contain unhatched eggs or small and unnoticeable larva.  If 10% or more of the crop becomes infected, commercial operations should consider using an insecticide,[17] however, this is not practical in a non-commercial setting, since the trees will eventually become quite large.  Traps can be used for monitoring, but they are generally not effective on their own.

Grafts and Seedlings


Delayed graft failure — as well as immediate failure — can be a problem, but it may take a few years to occur.  In addition, graft failure appears to be amplified near their hardiness zone limit as well as on transplanted trees.  Alternatively, using seedlings from the variety you wish to graft as a rootstock may increase compatibility.[18]

In one study, grafting within one's species had the highest success rate, while grafting hybrids had a lower success rate than grafting two different, non-hybridized species together.[19] However, a few highly incompatible variety and species combinations were discovered, for example, Chinese chestnuts grafted to European rootstock, and vise-versa, had little to no success.[19] In another study, whip and tongue grafts on non-irrigated rootstock had a significantly higher success rate than on irrigated rootstock, but it did not mention long term results.[20] Overall, this whole situation is very complicated, and none of the studies I've read were very satisfying as they all felt incomplete.

Many nurseries no longer sell grafted chestnut trees.  They generally sell seedlings from high quality Chinese varieties since their nut quality is often quite good. Seedlings from Japanese x European hybrids are sometimes sold as well, but their nut quality is more variable.

Nutrition


Chestnuts are unlike other nuts in that they are low in protein (2-10% vs 9-24%) and fat (1-10% vs 45-70%).  They are also high in carbs (35-45% vs 10-30%), very high in water content (35-60% vs 2.7-5.3%), and they are the only nut with a significant amount of vitamin C (25mg to 40mg/100g).  These qualities cause them to have a fairly short shelf-life if they are not dried or refrigerated properly.

It's difficult to determine, even a rough estimate of, the average nutritional content of the different chestnut species, because some of the results vary considerably.  It does, however, appears that the American chestnut may generally have the highest protein content of them all.  In one study that compared the American chestnut with Chinese and European chestnuts, the American had the highest protein content (4.8%).[21] The Chinese chestnut was close behind (4.2%), and the European had the least (2%).  All three had a fairly low fat content (~1.5%).  The American and Chinese chestnut consisted of less water (44%) than the European chestnut (~55%).[21]

In one source that compared the results (from multiple old studies) of two American chestnuts with two Chinese chestnuts and one or two European chestnuts (among others of an unknown species), both of the Americans had a fat and protein content around 10% and a water content of 33-47% (the rest primarily consisted of carbohydrates).[18] The Chinese chestnuts, one being the "Eaton" variety, had a protein content of 4.4%, a fat content of less than 2%, and a water content around 56%.  The European chestnut was 3.1% protein, 1.6% fat, and 52% water.[18]

More recent studies have shown that some European and Chinese chestnuts have a much higher protein content.  Seven European varieties from Portugal were tested, and almost all of them had a protein content over 5%, with two being around 7%.[22] Their fat content were between 1.73% to 3.1%, and their water content between 46.3% to 53.3%.[22] Chinese chestnuts from 4 different regions in China had a protein content between 7.54% to 9.74% and a water content of 46.43% to 49.75%.[23] Fat content was not measured.

Nut and Tree Sizes


Chestnut sizes will vary, sometimes greatly, by region and year.  Examples are given in the variety section so you'll know whether you should expect something on the larger or smaller side on a good year.

Sizes can also vary greatly within species, but European chestnuts are the most consistent at producing very large nuts.[24][25] Japanese chestnuts often produce very large nuts as well, but there is more variation within the species.  Chinese chestnuts regularly produce medium size nuts and the Americans produce the smallest nuts.  Chinese and American chestnuts are more likely to produce better tasting and easier to peel nuts than European and, to a greater extent, Japanese chestnuts,[24][25] although there are plenty of Euro-Japanese hybrids that are considered to be high quality and easy or fairly easy to peel.

Chinese and Japanese chestnuts produce smaller trees than European and American chestnuts.[24][25] They range between 30 to 60 feet in height at maturity.  Europeans grow about 20-30 feet larger.  All three grow in a spreading form, but it's more pronounced with the Asian species.  American chestnuts grow very fast in a columnar/timber form.  They can be as tall as 100 feet or more at maturity.[24][25]

American Chestnut and Chinquapin Foundations


Non-profit organizations are responsible for breeding blight resistance into the American chestnut and another American native, the Ozark chinquapin.  They rely on donations and volunteers to continue their work.  Making a donation and becoming a member is currently the best way to get your hands on seeds from the trees that have some form of blight resistant, however, resistance within the seedlings may vary.

The American Chestnut Foundation focuses on backcrossing American chestnuts with the genes responsible for blight resistance from the Chinese chestnut.  They are over 93% American.  Some of them also carried over C. mollissima's resistance to phytophthora root rot.  The TACF is also working on transgenic American chestnut trees.  They are nearly 100% American with the exception of a wheat gene responsible for excellent blight resistance.

The American Chestnut Cooperators Foundation is attempting to develop blight resistant American chestnut trees without genetic modification or the use of other chestnut species.  However, they do not make it easy to donate or obtain seeds and I have not seen any updates from them since 2017.

The Ozark Chinquapin Foundation is attempting to improve blight resistance of the Ozark chinquapin (Castanea ozarkensis).  In spite of being native to only a small part of the country, the Ozark chinquapin has significantly more genetic diversity than the American chestnut.  Although it's not entirely clear, this appears to have lead to the discovery of multiple trees with a greater degree of resistance than the American chestnuts that survived in their original form.  These trees are now being used by the OCF for cross pollination to selectively breed seedlings with improved resistance.
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Read More

Hybrid Chestnut
Castanea spp

Belle Epine

C. crenata x C. sativa.  Originated in France.
Zone
:
6a
Ripens
🍏:
late   :   one of the last to drop

Fruit Size
:
22 nuts/pound
Afflictions
:
Resistant to phytopthora root rot.  
Somewhat susceptible to chestnut blight.
Belle Epine's nuts fall in the burr, protecting them from wildlife.

Bergantz

Colossal x C. crenata
Zone
:
5b?
Fruit Size
:
very large, easy to peel
Afflictions
:
Somewhat susceptible to chestnut blight?

Big Euro

C. sativa x C. mollissima.  Originated in California.
Zone
:
5a
Ripens
🍏:
mid-late

Fruit Size
:
24 nuts/pound, easy to peel
Afflictions
:
should be at least somewhat resistant to chestnut blight.

Bisalta 2

C. sativa x C. crenata.  Originated in Italy.
Zone
:
5b
Blooms
💮:
  .......   :   poor pollen production
Ripens
🍏:
mid   :   precocious

Fruit Size
:
20-26 nuts/pound, easy to peel
Afflictions
:
Resistant to phytopthora root rot.  
Somewhat susceptible to chestnut blight.

Bisalta 3

C. sativa x C. crenata.  Originated in Italy.
Zone
:
5b
Ripens
🍏:
mid   :   doe well in cool summer climates.
somewhat precocious

Fruit Size
:
24-30 nuts/pound, fairly easy to peel
Yield
:
highly productive in cool summer climates. more likely to overproduce in more ideal climates, reducing nut size.
Storage
:
stores well
Afflictions
:
Resistant to phytopthora root rot.  
Somewhat susceptible to chestnut blight.
Bisalta 3 is more tolerant of wet springs than most other chestnut varieties.

Bouche De Betizac

Bouche Rouge (C. sativa) x C. crenata.  Originated in France.
Zone
:
4a? (5b)
Blooms
💮:
  .......   :   terminal buds may have some resistance to frost damage.
pollen sterile
Ripens
🍏:
mid (mid-late)   :   does well in cool summer climates.   anything later may struggle to fill their nuts.

Tree Size
:
timber form with vigorous growth?
Fruit Size
:
16-30 nuts/pound, fairly easy to peel
Yield
:
may overproduce, reducing nut size
Storage
:
stores well
Afflictions
:
Resistant to phytopthora root rot, gall wasp, and leaf anthracnose.  Somewhat resistant to chestnut blight.

Colossal

C. sativa x C. crenata.  Developed in California over 100 years ago.
Zone
:
5a? (4)   :   may be able to survive -28F
Blooms
💮:
  .......   :   pollen sterile
Ripens
🍏:
mid   :   early October in SW Michigan and probably W Washington as well (their ripening dates seem to align fairly well, but comparisons are limited).
precocious

Fruit Size
:
12-24 nuts/pound, hard to peel
Yield
:
may overproduce, reducing nut size
Afflictions
:
Somewhat susceptible to chestnut blight.
Colossal suffers from Internal Kernel Breakdown (up to 35%) when pollinated by Benton Harbor.

Eaton

C. mollissima x (C. crenata x C. dentata)
Ripens
🍏:
mid?   :   late September in central Missouri
Fruit Size
:
32-35 nuts/pound
Storage
:
stores well
Afflictions
:
Resistant to chestnut blight.

Gillet

Colossal x C. crenata?
Zone
:
4a
Ripens
🍏:
mid-late (late)

Fruit Size
:
12 nuts/pound, easy to peel
Afflictions
:
Somewhat susceptible to chestnut blight.

Layeroka

Skioka (C. mollissima x C. sativa) x open pollination
Zone
:
4
Blooms
💮:
  .......   :   pollen sterile
Ripens
🍏:
mid?   :   precocious

Tree Size
:
timber form with vigorous growth
Afflictions
:
Somewhat resistant to chestnut blight?

Luvall's Monster

C. mollissima x C. crenata x C. dentata
Zone
:
4a (3)
Blooms
💮:
  .......   :   pollen sterile
Ripens
🍏:
early-mid   :   precocious

Tree Size
:
upright growth
Fruit Size
:
moderate to very large, easy to peel
Afflictions
:
At least somewhat resistant to chestnut blight.  
Somewhat susceptible to splitting.

Maraval

C. sativa x C. crenata.  Originated in France.
Zone
:
5b (4a)
Blooms
💮:
  .......   :   produces an immense amount of pollen.
may be more susceptible to frost damage.
Ripens
🍏:
mid-late

Fruit Size
:
18-22 nuts/pound, hard to peel
Storage
:
stores well
Afflictions
:
Resistant to chestnut blight and phytopthora root rot.

Marigoule

C. sativa x C. crenata.  Originated in France.
Zone
:
4a
Ripens
🍏:
mid   :   somewhat precocious

Tree Size
:
upright growth
Fruit Size
:
24-30 nuts/pound, easy to peel
Storage
:
stores well
Afflictions
:
Resistant to phytopthora root rot.  At least somewhat resistant to chestnut blight.
Marigoule's nuts fall in the burr.

Marissard

C. sativa x C. crenata.  Originated in Italy.
Zone
:
6a (5b)
Blooms
💮:
  .......   :   pollen sterile
Ripens
🍏:
late

Fruit Size
:
10-24 nuts/pound, easy to peel
Afflictions
:
Resistant to phytopthora root rot.  Somewhat resistant to chestnut blight?

Marsol

C. sativa x C. crenata.  Originated in France.
Zone
:
5b (4a)
Blooms
💮:
  .......   :   buds open early, more likely to be damaged by frost
Ripens
🍏:
mid? (mid-late)

Fruit Size
:
22-28 nuts/pound, easy to peel
Afflictions
:
Resistant to phytopthora root rot.  At least somewhat resistant to chestnut blight (one of the most resistant of the Euro-Japanese hybrids).

Nevada

C. sativa x C. crenata
Blooms
💮:
  .......   :   frost sensitive buds
Ripens
🍏:
mid-late (late)   :   roughly 3 weeks after Colossal
Nevada may produce poor quality nuts in the East.

Okei

Silverleaf x open pollination? Contradicting reports: some say European, others say Japanese or a Japanese x pumila hybrid.  Developed in California.
Zone
:
5b
Ripens
🍏:
mid-late   :   2 weeks after Colossal

Fruit Size
:
16-26 nuts/pound, fairly easy to peel
Yield
:
below average productivity
Afflictions
:
Susceptible to splitting.
Okei may produce poor quality nuts in the East.

Precoce Migoule

C. sativa x C. crenata.  Originated in France.
Ripens
🍏:
early-mid
Tree Size
:
timber form with vigorous growth?
Fruit Size
:
24-32 nuts/pound, peels ok
Yield
:
may overproduce, reducing nut size
Storage
:
stores well
Afflictions
:
At least somewhat resistant to phytopthora root rot.  Somewhat resistant to chestnut blight?
Precoce Migoule produces inferior nuts to Migoule.

Regina Montis

C. sativa x C. crenata.  Developed in Washington.
Zone
:
5b
Ripens
🍏:
mid-late?   :   precocious
Fruit Size
:
22 nuts/pound, fairly easy to peel

Revival

C. mollissima x C. dentata
Ripens
🍏:
mid-late
Revival is considered to be the best selection from the Dunstan chestnut seedlings, but it often suffer from delayed graft failure.

Schlarbaum

C. mollissima x C. sativa
Zone
:
4b
Ripens
🍏:
mid-late

Fruit Size
:
22 nuts/pound, easy to peel
Afflictions
:
At least Somewhat resistant to chestnut blight.

Skookum

Zone
:
5
Blooms
💮:
  .......   :   pollen sterile

Tree Size
:
timber form with vigorous growth
Fruit Size
:
hard to peel
Afflictions
:
At least somewhat susceptible to chestnut blight.

Sleeping Giant

C. mollissima x (C. dentata x C. crenata)
Ripens
🍏:
mid?   :   late September in central Missouri
Tree Size
:
timber form
Fruit Size
:
28-35 nuts/pound
Afflictions
:
Resistant to chestnut blight.

Szego

C. sativa x C. mollissima x C. crenata.  Originated in California.
Zone
:
4b
Ripens
🍏:
mid-late

Fruit Size
:
22 nuts/pound, easy to peel
Yield
:
moderately productive
Afflictions
:
At least somewhat resistant to chestnut blight.

Torakuri

Colossal x C. crenata
Zone
:
5b?
Ripens
🍏:
mid-late? (late)

Fruit Size
:
15 nuts/pound, easy to peel
Afflictions
:
Somewhat susceptible to chestnut blight.

Chinese Chestnut
Castanea mollissima

AU Homestead

Developed in Alabama.
Ripens
🍏:
mid
Fruit Size
:
27-35 nuts/pound
Yield
:
moderately productive
Afflictions
:
Resistant to chestnut blight and phytopthora root rot.
wind storms may cause large burrs to drop early

Benton Harbor

Selected in Benton Harbor, Michigan.
Zone
:
5a
Blooms
💮:
  .......   :   early July in Michigan
Ripens
🍏:
  .......   :   somewhat precocious

Fruit Size
:
34-38 nuts/pound, easy to peel
Afflictions
:
Resistant to chestnut blight and phytopthora root rot.
Do not use Benton Harbor as a pollinator for Colossal as it has some sort of incompatibility that causes up to 35% of Colossal's nuts to decay before they finish ripening (Internal Kernel Breakdown).

Benton Harbor's nuts may drop with the burr.

Everfresh

Zone
:
5a
Blooms
💮:
  .......   :   early July in Michigan.
buds resisted frost damage in SW Michigan 2010 where most Chinese chestnut varieties received damage.
It has never received frost damage in the 15 years it has been there (2000-2015), although the climate is tamed by the Great Lake in comparison to much of the US.
Ripens
🍏:
mid-late?   :   after Colossal

Fruit Size
:
36-40 nuts/pound, easy to peel
Storage
:
long shelf life (roughly 1 year or more is implied when stored properly), hence the name "Everfresh".
Afflictions
:
Resistant to chestnut blight and phytopthora root rot.

Gideon

Developed in Ohio.
Zone
:
5a (4)   :   supposedly more cold hardy than most other Chinese chestnuts.
Ripens
🍏:
mid? (mid-late)   :   a few days after Peach and Qing.

Fruit Size
:
28-38 nuts/pound, easy to peel
Afflictions
:
Resistant to chestnut blight and phytopthora root rot.

Jenny

Zone
:
4
Ripens
🍏:
mid? (early-mid)

Tree Size
:
grows taller and more vigorously than most non-hybridized Chinese chestnuts.
Fruit Size
:
some of the largest non-hybridized Chinese chestnuts.
Afflictions
:
Resistant to chestnut blight and phytopthora root rot.

Mossbarger

Developed in Kentucky (1983).
Zone
:
4b (3)
Fruit Size
:
hard to peel?
Afflictions
:
Resistant to chestnut blight and phytopthora root rot.

Peach

Selected in Carrollton, Ohio.
Zone
:
5a
Ripens
🍏:
mid? (mid-late)   :   after Colossal.
early October in Missouri.

Fruit Size
:
23-38 nuts/pound
Afflictions
:
Resistant to chestnut blight and phytopthora root rot.  
Susceptible to splitting.
Terminal buds on the Peach chestnut are quite susceptible to frost damage in the Midwest, including SW MI where spring temperatures are more stable from the Great Lake.

Qing

Zone
:
4 (3)
Ripens
🍏:
mid? (mid-late)   :   after Colossal.
early October in Missouri.

Fruit Size
:
21-35 nuts/pound
Yield
:
may overproduce, reducing nut size
Storage
:
stores well
Afflictions
:
Resistant to chestnut blight and phytopthora root rot.
Qing is very susceptible to delayed graft failure, even on mollissima rootstock.

European Chestnut
Castanea sativa

Bracalla

Originated in Italy.
Zone
:
5b
Ripens
🍏:
mid?   :   does well in cool summer climates.
Afflictions
:
Susceptible to phytopthora root rot.  Somewhat susceptible to chestnut blight.

Marron Di Comballe

Originated in France.
Zone
:
5b
Blooms
💮:
  .......   :   pollen sterile
Ripens
🍏:
  .......   :   does well in cool summer climates (implying it ripens between early and mid season).

Fruit Size
:
24-32 nuts/pound, easy to peel
Afflictions
:
Susceptible to phytopthora root rot.  Somewhat susceptible to chestnut blight.

Marrone Di Marradi

Originated in Italy.
Zone
:
5b
Ripens
🍏:
mid-late   :   mid to late October in W Washington

Fruit Size
:
22-26 nuts/pound, easy to peel
Yield
:
less productive than sativa x crenata hybrids
Afflictions
:
Susceptible to phytopthora root rot.  Somewhat susceptible to chestnut blight.

Marrone Di Susa

Originated in Italy.
Zone
:
5b
Blooms
💮:
  .......   :   pollen sterile
Ripens
🍏:
late

Fruit Size
:
22-26 nuts/pound, easy to peel
Storage
:
stores well
Afflictions
:
Susceptible to phytopthora root rot.  Somewhat susceptible to chestnut blight.
Marrone di Susa's nuts fall in the burr.

Japanese Chestnut
Castanea crenata

Labor Day

at least partially C. crenata.  Selected in Perry, Michigan.
Zone
:
5b
Blooms
💮:
  .......   :   sheds pollen for 3 weeks
Ripens
🍏:
early-mid (early)   :   2nd or 3rd week of September in SW Michigan

Tree Size
:
grows more like a Chinese chestnut (slower than the other species)
Fruit Size
:
32-40 nuts/pound, easy to peel
Yield
:
less productive than sativa x crenata hybrids
Afflictions
:
Resistant to chestnut blight and phytopthora root rot.

Yoo Ma

C. crenata.  Originated in Korea.
Zone
:
5b
Ripens
🍏:
early-mid   :   precocious (2nd or 3rd leaf)

Tree Size
:
grows quite slow for a chestnut
Afflictions
:
Resistant to chestnut blight and phytopthora root rot.