About Chestnuts - The Native Rock Stars
Chestnuts are our Native Rock Stars.
Chestnuts have been grown throughout Europe, China, Japan and United States as a food staple since time immemorial. The Native American chestnut trees are susceptible to the chestnut blight and are all but eradicated. The foreign Chinese chestnut trees brought a blight (Cryphonectria parasitica) to North America that the Chinese trees are resistant to. The native trees are now being crossed and back crossed to develop blight resistance by The American Chestnut Foundation (TACF) and other researchers.
Chestnut trees and their close relatives come in all sizes from bush to “Redwood” timber size. The American chestnut tree is a very large timber type tree with relatively small chestnuts. The European, Japanese and Chinese chestnut trees have a long history of being cultivated for nuts and the named selections are generally a size similar to a standard apple tree with large nuts that can be 10 nuts to the pound. The chestnut industry is growing as the crop is sustainable, soil friendly and well accepted by the consumer. According to a recent newspaper report, a 17 acre chestnut orchard and winery in upstate NY sold out of chestnuts in one day during their chestnut festival selling chestnuts at $3.50 per pound. Chestnuts typically sell for $7.00/lb.in stores.
A mature well planned and maintained hybrid chestnut orchard with a proper mix pollinizers and pollen sterile trees should achieve well over 2000 to 3000 pounds of nuts per acre. The trees will grow wherever in North America there is enough warmth, well drained soil and rain, as the native area is expansive as shown in Figure #1. Chestnuts are now grown from Michigan to Florida.
Fig. 1 Chestnut Native Range in dark green
Commercial chestnut orchards are currently suggested to have either European and/or Japanese hybrids in an orchard or have Chinese hybrids in an orchard; but, do not have both types of trees in the same orchard. A phenomenon known as Internal Kernel Breakdown (IKB) has been described by Dr. Fulbright of Michigan State University Extension. The main cultivar grown in Michigan is Colossal and it was found when nuts from Colossal were pollenated by a Chinese chestnut tree that up to 30% of the nuts would quickly rot internally making the crop suspect at best. Also in Michigan growers have found the European and Japanese hybrids produce 2 to 5 times the nuts that Chinese chestnuts do and produce nuts at a much earlier age. For example, the tissue cultured Colossal variety, a European and Japanese hybrid, is pictured above center, is only 6 months old and producing flowers already.
Like any fruit, grain or nut crop there are pests and diseases that like it as much as we do. The main issues are: chestnut blight, chestnut weevil and root rot. Another potential pest not seen here in our farm is the Asian chestnut gall wasp. Chestnut trees like any tree are also subject to the normal leaf eating pests and normally they can be controlled if necessary with traps.
It is important to plant chestnut trees in well drained soil as chestnut trees are susceptible to root rot where the soil remains wet for extended periods of time. A farmer always knows where the wet spots are in the field as they are in the low lying areas and swails where water drains first before draining further downhill. Japanese chestnut strains are most resistant to root rot and some hybrids are as well. It is best to avoid wet areas and keep in mind that the odd wet year may cause your 10 year old chestnut tree to die from root rot.
Chestnut blight is a common problem and is caused by a Cryphonectria parasitica a pathogen that generates oxalic acid that causes cankers on the bark of the tree. The cankers can weaken the wood and if left unattended can fully girdle and kill the tree. Hypoviruses have been found that infect the blight pathogen and allow recovery of the blight wound. In Europe and in Michigan (and other areas) the hypoviruses occurred naturally. There are different strains of hypoviruses that are effective against different strains of the chestnut blight. MSU Extension hopes to have a blight management procedure developed in the next few years to control blight in orchards. In the meantime growers in Europe and the US have found control using an ash paste or mud pack to control the cankers (wounds).
Mudpacking is a method to heal a canker wound. You only need some raw untreated soil (good organic soil, or compost), some plastic (we suggest white plastic) and a way to hold the plastic in place. Turn the soil into a sticky consistency and plaster completely over the blight canker. Then wrap the plastic around the tree covering the wound to keep the dirt damp. Then hold the plastic in place with string, wire or tape. If the plastic is long enough you could even just tie the plastic around the tree. After two months, the plastic can be removed and the wound should show signs of healing. This means the blight for that wound has been eliminated. This doesn’t mean the tree is healed, only that canker is healed. Using wood ash paste is another method used in Europe and we are currently unsure of the details and we will inform you as someone informs us or we feel that our experiments yield good results. Seems that the ashes may neutralize the oxalic acid allowing the tree to heal and if that proves to be true we may have even easier solutions.
The best method to control chestnut weevil is with preventative measures. As the nuts drop they must be picked up off the ground within two or three days. The weevil larva emerges from the nut a few days after they are on the ground. If the nuts have been gathered you break the life cycle of the weevil. Nuts that are gathered need to be subject to a 120F +/-2F water bath for 20 minutes to kill the larvae and allow the nut to still be viable. Nuts that had larvae in them will have a small pin hole the size of pencil lead. You will know if you have them as the larvae are little white grub/maggots.
If you see much more than 5% of the nuts have weevils then you will need to most likely spray insecticide to control them. An excellent paper is located at: http://www.centerforagroforestry.org/weevil.pdf.
Orchard Planning and Management
Spacing is dependent on the tree cultivars selected. Current recommendations are to double plant the trees and cull every other one when they become overcrowded. For European and Japanese hybrids the final spacing of 30’ X 30’ (48 trees per acre)should be good and anything less than 20’ X 30’ will be too tight. For an excellent practical overview please see: http://msue.anr.msu.edu/topic/chestnuts/establishing_orchards/planting_and_spacing.
The soil pH must be proper for the tree to grow and thrive. Soil pH should be 5.5 to 6.5 much lower or much higher the trees won’t do well. If the tree is chlorotic(yellow) it is a good sign that the soil is near neutral (7.0pH) and the pH needs to be adjusted if possible or do not plant in the area.
Fertilization will depend on the age of the tree and size of the tree. Leaf analysis is used to verify the condition and needs for macro (N,P, & K) and micro nutrients. Fertilizer recommendations usually include ammonium sulfate to acidify the soil around the tree. Again a very practical paper is at the MSU Extension at: http://msue.anr.msu.edu/topic/chestnuts/horticultural_care/fertilizing.
Irrigation is usually needed for transplanted trees for either bare root or potted trees for continued growth and survival. Bare root trees are freshly dug up and a majority of the roots have been cut off during the digging. If the tree is a potted tree, the root system has been constrained. Potted plants are usually watered to near ideal conditions, allowing the tree top to grow much more than the roots would normally allow. Although the potted tree may be in better shape when planted out, the tree will not have similar conditions and also need to be watered. The newly planted trees must be watered by hand, or irrigated. We have done both depending on the location and the amount of trees planted. If planting out an orchard nearing an acre in size we strongly suggest looking into drip tape. The hose is extremely cheap and you simply lay the hose along the row of trees and poke a hole in the thin walled hose, twist on a dripper near each tree base. Connect the end of the tape to a water supply. The water supply could be a big plastic tank uphill or a nearby water source pumped with a pressure regulation directly to the tubes or to the tank. This is just one method and great advice is from other orchardists or talk to your extension agent. Also, go to the local greenhouse supply store and talk to them as they sell what is commonly used and how to use it. Bottom line is the soil needs to be moist 12” – 18’ down and not be so wet it forms a ball that water drips from. We cannot over emphasize the need to water the first year and ideally 2 or 3 years until the roots go deep enough to not need irrigation if your area generally receives enough rain.
We describe the practices for an orchard and the above will apply for the homeowner or hobbyist and any agricultural system. Different systems include: silvopasture, permaculture, agroforestry and woody agriculture. These systems utilize trees as an integral part of a sustainable agricultural practice. We believe this trend will continue to grow and lead both environmentally and economically over annual grain crops.
"You know planting trees are good for the environment; but, nut trees are good for you too"