SONG News June 2003 no. 65
In this Issue...

Why Hybrids, Chestmutts
John H. Gordon Jr.

This was to be a paper to accompany my show and tell of a bag of chestnuts from my farm, AKA research farm. Hybrid chestnuts are like dogs, mutts, mongrels. They are not like our cats. Cats look like each other. Dogs are weird. Chestnuts are weird.

We have crossed three species of chestnut: Japanese, Chinese, American to gain all these mutts. We is a northern we, and our breeding material is the 'northern sorts in these species'. Korean and European were left off the list because we have made all the mutts in my bag without resorting to them.

(Here comes dispute.) Korean is widely known as a cross between Chinese and Japanese. Actually it is not. Cliff England has done research in Korea which gave him ample time to become familiar with Korean chestnut. " The 'original Korean' was out of Manchuria and Siberia. It is a northern Chinese which still exists in Korean and Manchurian forests." I looked for the land bridge which led the Korean to Japan. None existed, but a land bridge did link Siberia with Japan from the north for geologic periods earlier than the Pleistocene Period, the ice ages. Suddenly a light comes on why Japanese is so different from Chinese. It is an ancient separation of these species." Recently there has been a lot of crossing of Japanese and the 'original Korean'. This is recorded in old tombs and texts." Observing genetic DNA for variation leads to the same conclusion, or 1 thought Dr. Sandra Anagnostakis was confirming this when she sprung it about the different genetics of several Korean varieties ("Exception of Pochun B-1gou and Buyu3 gou which are quite different from the other tested Korean chestnuts and from mollissima") Ouch, bit in the ass by more mutts.

And so it goes with 'Marrone european'. The original European cross with Oriental (Chinese, Japanese, their hybrid, or southern species of Chinese) was made and recorded in the history of the silk road from China to become the Marrone. The Marrone European which we see in stores around Christmas time is this cross. American and the original European separated when Newfoundland separated from Scotland, yet the American-like trees remain, and are scattered over northern England and northern Europe. These trees are so close to native American that the guys with the microscopes are continually classifying turgid upland American chestnut leaves as from European hybrids, and visitors to the estates in northern England assume their chestnut trees are American.

Go figure. Even if we got the recent history of the Korean and European wrong, and remember we are never wrong, we are trying for better forms of Koreans and Marrones. Access to the most hardy and resistant Marrones and Koreans should save us time selecting through generations of Japanese hybrids for pleasant and fixed traits. Maybe not, because we are well into constructing American Korean and Marrone American types from the more basic crosses, and better yet, crossings of more intrepid growers of Korean and Marrone who have already crossed Marrone, Korean, Chinese, Japanese, and American. Today Marrone-crossing actually adds to our breeding time because these precociously large size. European nuts, which southern Europeans sought and gained, ruined winter hardiness needed in our fluctuating northern climate. Ever the "large chestnut" breeder, Ernie Grimo is crossing Swiss #5353 and Connecticut's Japanese x American hybrids. Connecticut's Japanese x American hybrids are genetically most like Pochun B-1 gou and BuyuS gou, as mentioned above as the" quite different Korean". If Ernie could grow out and stress the nut wonders he produces he would ease northern chestnut growing. 'Recent Korean' adds hardiness, and the blight resistances of Chinese to Japanese. This cross has already put the tiny buds of Japanese on Chinese for gall wasp resistance.

Traits we see in Japanese:

  1. Blight resistance which is equal, but different from Chinese.
  2. Able to set top bud in a cool, short season.
  3. Able to grow a large nut in our cool season.
  4. Able to grow on cool, more moist, neutral (pH 7) soil.
  5. Tiny buds which discourage bud gall insects.
  6. Conservative bearing with few and small nuts until Japanese trees are large, and their root systems are extensive.
  7. Thin, non hardy bark where young trees typically decline to multi stems due to Southwest injury, and -29C (-20°F) temperatures.

Traits we see in Chinese:

  1. Blight resistance which is equal, but different from Japanese.
  2. Thin pellicle which easily skins off the smooth, medium size nut kernel.
  3. Hardiness between Japanese and American if the growing season is hot enough and long enough.
  4. Excellent flavour medium size northern nuts which are larger and more solid than American.
  5. Twig blight susceptibility which can be as bad as the bark blight.

Traits we see in American:

  1. Short, fluctuating-season hardiness up to the tip bud, a hardiness which extends the chestnut range to nearly the range of butternut above the lower Great Lakes.
  2. Two strains, one for acid droughty soil and timber, another for pH 6.x calcium-magnesium, moderate-water-table soil for up to 1" nuts.
  3. Nuts with more glycerides which enhance sweetness and frost protection in uncured nuts.
  4. Some blight resistance in some remaining trees.

We have gone generations into hybridizing chestnuts, enough to see what is working and what is so frustrating it only gives a glimmer of hope. By far the most successful hybrid in the Great Lakes region is the Japanese hybrid. These are not first generation hybrids due to their tender bark, but are crosses with three part hybrids, many from Jack U. Gellatly's former planting in British Columbia. The 'Colossal', a Japanese x Marrone hybrid, is almost too tender to grow, and cross, though it has met with some success in Michigan. It is unlikely clever growing will get around the bark injury and sloughing due to Southwest injury seen in our recent mild winters. Clever breeding and stressing is needed to ferret out hybrids that retain tips after -31C (-25°F) winters.

Why do American people think a hybrid chestnut is automatically a Chinese x American? Because most crossing was done near Washington, DC where large Chinese chestnuts are plentiful, and their first generation hybrids are hardy. Later hybridizing moved to Connecticut where Japanese and Japanese hybrids are hardy even in their first generation. Chinese chestnut is much better tasting than Japanese. Chinese adds bark blight resistance even in first generation. However, farther north Chinese is susceptible to twig blight. Twig blight can descend down the twig into the bole of the tree, and make it look like it is housekeeping for a flock of woodpeckers. This same infested Chinese could be a prize selection in the South, but worthless in the North because temperatures below -18C (0°F) is what kills the infected bark. Japanese adds blight resistance, early ripening nuts, and cool season hardening trees much better adapted to Ontario or New York though imperfectly in the first generations of their hybrids. People do not like the habit of Japanese type trees girdling down, then sizing several leaders larger than pole size trees before large nuts and bumper crops are produced. The Marrone hybrids of today usually give a few good crops of large nuts before their energy and fluids-circulation drops, and they decline into large crops of small nuts, then expend all their energy in bearing in too cool and too short a climate. Bark injury is inevitable which leads to resprouting up from the ground to do this cycle again. Now, we looking through the seedlings these produce.

One has to grow many chestnut hybrids to perceive that the surviving population is slowly moving to more and more Japanese characteristics. A grower with a few trees who is growing out his selections needs more than a lot of luck because magic bullet breeding is not chestnut breeding. We find a good tree among many failures. Moving to the next generation of better trees is usually lost due to lack of tree numbers and harsh, challenging conditions which push the next generation to a remnant of good hybrid seedlings.

Once we see which way successful breeding is going, the process is simplified. Some sources of Japanese used today are from Connecticut, Etter, various parks, and plantings. However, most of us in the Society of Ontario Nut Growers were led to Japanese through Gellatly hybrids. Japanese have the skinniest leaves. Shiny leaves is maximized in the 'Skookum' (Gellatly's 'Skyoka' derivative) which is like looking at a holly. Original Gellatly hybrids often look like Chinese x Marrone. Later generations of Gellatly hybrids have given good hybrids, very few, due to containing too much Marrone European. Gellatly hybrids which made hardy trees were early ripe, and close examination showed the purple tinge of Japanese bark. Then we see more Japanese characteristics in buds, leaves, twigs, stems, nuts and burs. Keying in on second year seedlings which retain shiny leaves keeps us going in the right direction by staying with Japanese derived hybrids.

The perception grows that eventually most of our chestnuts orchard trees will be Japanese x Chinese x American hybrids. Sorting generations, these nuts will yield top quality hybrids called 'I don't know'.

Andrew Dixon 1907-2002

Longtime member of SONG, and Forester extraordinaire. Andy's presence will be missed by all of those who knew him. Andrew Dixon of McGillivary Township is recognized for his lifelong dedication to education, innovation and conservancy in agriculture. Throughout his 32-year career as a high school science and agriculture teacher, his innovative teaching methods influenced many rural students to continue in school and thereby increased the level of education in the farming community. Following his retirement from teaching, he worked with the Stew-art Seed Company of Ailsa Craig as a corn plant breeder developing new hybrids for this area using winter nurseries in Jamaica, New Zealand and Argentina. Beginning in the early 1950's, Andrew worked to promote their mandate and was an acknowledged proponent of hardwood production as a viable crop in Southern Ontario.

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