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Stebbins, R.L. 1990. Requirements for a United States chestnut industry. p.
324-327. In: J. Janick and J.E. Simon (eds.), Advances in new crops. Timber
Press, Portland, OR.
Requirements for a United States Chestnut Industry
Robert L. Stebbins
- INTRODUCTION
- THE CHESTNUT INDUSTRY
- U.S. Markets
- Cultivars
- Pests and Diseases
- Range of Production
- Propagation
- Orchard Establishment and Productivity
- Harvest Mechanization
- Storage
- PROCESSING
- PROSPECTS
- REFERENCES
At present there is no U.S. chestnut (Castanea spp.) industry. Certain
conditions must be met for the industry to develop to even modest levels of
production. First, trees of high quality cultivars with resistance to chestnut
blight must be made available in quantity It will be necessary to develop or
improve mechanical harvesting, shelling, and peeling. Since many Americans
alive today have never seen a chestnut, a marketing effort to familiarize them
with this "exotic" nut and its uses will be needed. Established markets for
exported nuts exist in Japan and other countries where consumers are familiar
with it. Since removal of the "skin" (pellicle) from the kernel is too
time-consuming for most homemakers, already-peeled kernels should be marketed.
Before the chestnut blight incited by Cryphonectria parasitica Murr.
(formerly Endothia parasitica [Murr.]), was introduced from China on
Chinese chestnut trees (C. mollissima Bl.). America had a chestnut
industry based on wild stands of Castanea dentata Borkh. That industry
vanished a half century ago as the disease decimated the American chestnut.
The USDA Foreign Agricultural Service reported 4,293 metric tons of chestnuts
imported in fiscal 1986-87, and 3,441 tons in 1987-88 (J. Young, pers.
correspondence), valued at 6.5-6.7 million dollars. The primary exporter of
chestnuts to the U.S. was Italy with about 84% of the volume, followed by
China, Spain, Korea and eight other countries. In addition, an unknown
quantity of dried chestnuts were imported. Wholesale prices have been $2.10
per pound ($4.62 per kg) for the larger sizes. Nuts are sterilized in Italy,
brought here in sea containers, and fumigated using methyl bromide in port as
required by USDA Animal and Plant Health Inspection Service (APHIS). Fresh
nuts are refrigerated.
The most traditional use of chestnuts is roasted whole, with the shell and
peel. Roasted chestnuts are sold in fall and winter on street corners in most
Eastern cities. In Japan, Chinese chestnuts from Korea are marketed in that
fashion. Peeling is done by the customer as the nuts are eaten.
The chestnut market in the northeastern U.S. is not entirely an ethnic one, but
it is centered around the Thanksgiving and Christmas holidays. Recent
immigrants of Italian, Portuguese, Chinese, Korean, and Japanese origin, form
the most receptive markets for in-shell chestnuts which could be produced in
U.S. orchards. In the west, Oriental food stores are a natural first
opportunity. Because of the problems in storage, fresh chestnuts are available
only seasonally. New Zealand is preparing a chestnut industry for export
primarily to Japan (New 1988). U.S. marketers could come into that same market
six months later. The volumes of processed chestnuts which could be marketed
probably are greater than those which could be sold fresh. Marketing will
probably not pose a problem until U.S. production reaches a hundred tons or
more. If orchards average two tons of nuts per acre, this level of production
could be reached quickly once suitable nursery stocks are available. Market
research will be required both for the domestic market and to explore export
opportunities.
Nuts from seedling trees will not be satisfactory except in the short run,
while supplies of domestically produced chestnuts are very small. Resistance
to chestnut blight must be the first criterion for a cultivar. The blight has
occurred in Oregon, and was found by OSU Extension Agent Robert Rackham in
orchards in California. There are no regions of the U.S. where the blight is
not a potential threat. Of those cultivars of European parentage which have
been preserved in California, 'Collosal' is not blight resistant but
'Silverleaf', which has not developed the blight in orchards where the blight
exists, appears to have some resistance. Chestnut blight was found in Oregon
and eradicated (Holdeman 1984). Oregon State University has brought in blight
resistant "Dunstan" cultivars 'Revival' and 'Carolina' from Chestnut Hill
Nursery in Florida, under quarantine by the Oregon Department of Agriculture.
They have been planted at the Lewis Brown Horticultural Research Farm,
Corvallis, and kept under close scrutiny for any evidence of the blight.
Progress has been made in breeding blight-resistant chestnuts (Burnham et al.
1986, Jaynes 1975).
A second important characteristic of a good chestnut cultivar is the ease with
which the "skin" or pellicle can be removed from the kernel. The flavor of the
pellicle is so astringent that few people would eat them without first removing
it. The French classify chestnuts into "marron" types and other. With
marrons, the "skin" (pellicle) is not convoluted into the kernel. If they are
true to their reputation, 'Collosal' kernels can be peeled very easily The
"Dunstan" hybrids also have this reputation. Japanese chestnuts (C. crenata
Sieb. & Zucc.) are hard to peel, as are Chinese chestnuts. Japanese
chestnut breeder Dr. Yoshihiko Sato at Yatabe Fruit Research Station, Japan, is
currently screening selections which are sweet and peel easily. The
Chinese-American hybrids are also difficult to peel.
Although the decline of the European chestnut industry has been blamed on
chestnut blight (Caries 1984), lack of mechanization in processing may also be
partly responsible. While some Japanese blame Korean competition for the
decline in their industry, Japanese housewives' reluctance to peel the nuts may
also be a factor. If a chestnut industry is established in the U.S., its
growth will eventually depend on some way to mechanically shell and peel the
kernel in preparation for market.
While large sized nuts are easy to sell at profitable prices small ones are
not. Chinese chestnuts are small to medium in size, 4.5-13 g (Wallace 1986),
and 20 g is large for a Chinese chestnut (Miller 1988). American chestnuts,
are small, 3-6 g, Japanese chestnuts are large, while European chestnuts are
large and variable, some peeling quite easily, others with great difficulty.
"Dunstan" hybrids are claimed to be large, weighing 13-20 g (Wallace 1986).
The native American chestnut, has been almost entirely killed by chestnut
blight. Breeders have produced new cultivars of blight-resistant chestnuts by
hybridizing C. dentata with C. mollissima (Jaynes 1979) and
backcrossing. Significant progress in the area of blight control has been made
lately (Griffin 1986).
In Japan, chestnuts are highly susceptible to trunk cankers caused by a fungus
of the genus Phytophthora. Nurserymen in Australia (Rinaudo 1988) and
breeders in Japan (Yoshihiko Sato, Yatabe, pers. commun) find that European
chestnut is even more susceptible to this disease than Japanese. With careful
water management in dry climates Phytophthora trunk rot can be
avoided.
Oregon maintains a quarantine against chestnut materials with the following
insect pests: large chestnut weevil, Curculio proboscideous F., small
chestnut weevil, Curculio auriger Casey, nut curculio, Conotrachelus
spp. and oriental chestnut gall wasp, Dryocosmus kuriphilus
Yasumatsu (Oregon Dept. Agric. 1986).
In western Oregon, severe depreciation of chestnut trees by deer has occurred.
Groundhogs were a problem in Ohio (Miller 1988), as were periodical cicadas.
With its low chilling requirement, 20-30 days of chilling (Westwood 1978),
chestnuts can be grown as far south as Florida. Some cultivars of Chinese and
American chestnut are hardy enough for conditions in the northeastern U.S.,
withstanding -20°C after sufficient acclimation. Chestnut seems to be
tolerant of high summer temperatures in the central valleys of California.
These characteristics give the nut a very wide potential production range.
Japanese nurseries use veneer grafting for propagation of chestnut. An
Australian nurseryman uses T budding when the little leaves are just beginning
to emerge in spring. With chip budding, a large, 2.3-3 cm bud base is used.
Most U.S. nurseries graft onto dormant rootstocks in spring (Lagerstedt 1988).
Some grafters have experienced much difficulty due to root pressure flooding
out the grafts. Grafted trees have often died a year or more after
transplanting, due to graft failure (Berganz 1988). Chestnuts can also be
increased through micropropagation (Chevre and Salesses 1985).
Chestnut trees begin to produce at an early age, and can produce two tons or
more of fresh nuts per hectare (Burnett 1988). Irrigation appears to be
necessary for quick establishment in the dry summers of western Oregon.
Central leader training appears to be best for strong limb structure.
The nuts fall to the ground within about a week after they have become ripe in
the hulls. Once fallen, they are subject to depredation by birds, squirrels,
and mold. Since the nuts fall over a period of several weeks, several harvests
are required to get a maximum yield of high quality nuts. More frequent
harvest will be required where autumn weather is rainy
Some progress in mechanical harvesting has been made (Miller 1988). John
DeMartini, chestnut grower in Linden, California (DeMartini 1983), cited hand
harvest as the major cost which requires a high market price if chestnut
production is to be attractive to U.S. growers. Many nuts come down in the
burs, and will have to be removed mechanically DeMartini uses a converted
walnut huller. Chestnuts are softer than walnuts, and could be more easily
bruised. Most cultivars will require multiple picks to avoid deterioration on
the ground while waiting for the rest of the crop to come down.
Chestnuts are usually not dried. They are stored fresh. They attain a
rock-like hardness if dried to a moisture content below about 15%, and are
useful only for grinding into flour. Unless they are held at cold
temperatures, they will mold in storage. Dooley et al. (1980) stored European
chestnuts in Australia, in air and controlled atmosphere storage (2.5% CO2:2%
O2) at 0°C. Quality was monitored with measurements of weight loss, soluble
solids, starch content, and fungal deterioration. Chestnuts were successfully
stored for 13 weeks in both air and controlled atmosphere storage, but fungal
deterioration was lower in the controlled atmosphere. They dipped the
chestnuts in a solution of 100 ppm Rovral and 100 ppm benlate with 0.1% Tween
20 as a wetting agent immediately after harvest. All air-stored chestnuts were
placed in polystyrene plastic trays and loosely wrapped with plastic bags to
retain moisture. During both air storage and controlled atmosphere storage
there was a reduction in starch content and an increase in soluble solids.
This was detected as a sweetening of the chestnuts during flavor assessments.
Fungal infection was 10-15% in the air stored nuts and only 0-5% in CA stored
nuts.
Curing, or partial drying of chestnuts before storage, has been recommended to
sweeten nuts by converting some of the starches into sugar. Curing is not
required before cold storage because starches are slowly converted into sugar
during storage. Curing may decrease the quality of chestnuts by allowing
fungal invasion and moisture loss after harvest.
About 70% of the consumption of Japanese chestnuts is used for boiled or
steamed nuts (Itoo 1984). The remainder (30%) are for processing into sugar
syrup products and "marron glace," a glazed candy. Many confectioneries
process the nuts into products such as chestnut candy, mashed sweet potato with
chestnut, and cake with chestnut. The most important problem in processing is
peeling the pellicle of the chestnut. About 80% of the labor in processing is
used in the peeling process, which is mostly done by hand using a knife. This
causes the high cost of chestnut confectioneries. Thermal blast peeling is a
process which holds promise for chestnuts (Harris and Smith 1988). Chestnut
flour is useful for baking (Berganz 1988), and is safe for people who are
allergic to wheat products.
U.S. producers could displace imports and expand the U.S. market for in-shell
chestnuts, but a much larger tonnage could be marketed if a peeled product were
made available (Miller 1988). It is unlikely that many homemakers will want to
do that job in their own kitchens.
Either partial or complete answers to most problems of chestnut production have
been developed. Some progress on mechanical harvesting has been made in
California (Robert Rackham, personal communication) and in Ohio (Miller 1988).
Thermal blast peeling has been successful on an experimental scale in Alabama
(Harris and Smith 1988). Storage techniques have been developed (Dooley et al.
1980). Insect and diseases of chestnuts may be kept out of the Pacific
Northwest through use of quarantines (Oregon Dept. Agric. 1980). Propagation
of chestnut trees can be accomplished by budding, grafting, or other means
(Lagerstedt 1988). By continuing to improve the crop and addressing the
processing and marketing problems, domestic production could replace about
4,500 tons of imported nuts, and expand domestic consumption.
- Berganz, R. 1988. Experiences with the California Chestnut Industry. Proc. 2nd
PNW Chestnut Congress. Chestnut Growers Exchange P.O. Box 12632, Portland, OR
97212.
- Burnham, C.R., P.A. Rutter, and D.W. Treveli. 1986. Breeding blight-resistant
chestnuts. Plant Breed. Rev. 4:347-397.
- Burnett, M. 1988. The potential for a chestnut industry in the United States.
Proc. 2nd PNW Chestnut Congress. Chestnut Growers Exchange P.O. Box 12632,
Portland, OR 97212.
- Carles, L. 1984. Le chataignier reland d'une production en declin.
L'Arboriculture Fruitiere 368 (Nov).
- Chevre, A.G. Salesses. 1985. Micropropagation du chataignier problems et
perspectives. 5th Colloqusim on Fruit Research INRA Pont-de-la-Maye, Bordeaux,
France.
- DeMartini, J. 1983. Nut grower. West. Agr. Publ. Co. Inc. Jan-Feb 1983.
- Dooley, L.B., R.L. Brohier, and C.R. Little. 1980. CA and air storage of
chestnuts. Hort. Res. Inst. Burwood Hwy, Knoxfield, Victoria, Australia.
- Griffin, G.J. 1986. Chestnut blight and its control. Hort. Rev. 8:291-336.
- Harris, H. and D. Smith. 1988. Method and apparatus for thermal blast peeling,
skinning, or shelling of food products. Proc. 2nd PNW Chestnut Congress. P.O.
Box 12632, Portland, OR 97212.
- Holdeman, Q.L.1984. History of seven separate outbreaks of chestnut blight in
Western North America. CA Plant Pest and Disease Rpt. 3, (4, July).
- Itoo, Saburo.1984. Chestnut processing. New Zeal. DSIR Div. Hort.and Proc. May
- Jaynes, R.A. 1979. Chestnuts. p. 111-127. In: Nut tree culture in North
America. The Northern Nut Growers Assoc. Inc.
- Jaynes, R.A. 1975. Chestnuts. p. 490-503. In: J. Janick and J.N. Moore (eds.).
Advances in fruit breeding. Purdue Univ. Press, West Lafayette,IN.
- Lagerstedt, H.B. 1988. A review of chestnut propagation. Proc. 2nd PNW Chestnut
Congress. Chestnut Growers Exchange P.O. Box 12632, Portland, OR 97212.
- Miller, G. 1988. Considerations for commercial chestnut production in Eastern
U.S.A. Proc. 2nd PNW Chestnut Congress. Chestnut Growers Exchange P.O. Box
12632, Portland, OR 97212.
- New, E. 1988. The chestnut industry in New Zealand. Proc. 2nd PNW Chestnut
Congress. Chestnut Growers Exchange P.O. Box 12632, Portland, OR 97212.
- OR Dept. Ag. Chestnut blight quarantine 1987. OAR 603-52-075. Oregon Dept.
Agric., 635 Capitol Street NE, Salem, OR 97310.
- Rinaudo, J. 1988. Chestnut production in Australia. Prod. 2nd PNW Chestnut
Congress. Chestnut Growers Exchange P.O. Box 12632, Portland, OR 97212.
- Wallace, R.D. 1986 The Dunstan hybrid chestnut. Chestnut Hill Nursery Inc. Rt
1, Box 341, Alachua, FL 32615.
- Wallace, R.D. 1988. History of breeding and production of hybrid chestnut
cultivars. Proc. 2nd PNW Chestnut Congress. Chestnut Growers Exchange P.O. Box
12632, Portland, OR 97212.
- Westwood, M.N. 1978. Temperate zone pomology. p. 81. W.H. Freeman and Co., New
York.
Last update March 11, 1997
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