How to Kill a Chestnut Tree

This chapter is not really about killing chestnut trees, its about the things that will kill a chestnut tree. Some chestnut trees are munched to death. Take a look at the munchies page to find out what eats chestnut trees/.

Clay - Everybody's Got Some
Well known to the chestnut experts at the big universities is that chestnut trees will not grow in heavy or clay soils. If you spring plant a bare root chestnut tree in clay soil, it will bud out and start to grow. The growth you see is called top growth (leaves and branches). Top growth comes easy for chestnut trees. Bottom growth (roots) is much more difficult. The clay soils are difficult for the chestnut tree's roots to penatrate. Since the roots can not grow then the tree will use its stored reserves trying to put forth new growth but will fail (Photo 1). A chestnut tree planted in clay soil may make it through the first year. If the top growth is examined, the growth lacks sizable buds that form and would be next years new growth. Without these buds the tree will not make it to the next spring.

How Wet is too Wet?
Wet soils are somewhat tolorated by chestnut trees depending upon the season of the year and the chestnut tree cultivar. Lets start with the season because it is easier to visualize. Starting with late fall, after the chestnut trees go dormant, the chestnut trees can take a drenching, or even a flood where part of the tree is under water. As long as the chestnut tree remains dormant water saturated soils have minimal impact on the health of the tree.

Several chestnut cultivars are known to tolorate heavier soils than others. Ongoing testing of cultivars in heavy soils has demonstrated that some European cultivars (Castanea sativa), in particular Marival, Marigoule, Marsol, and Precoce Migoule will grow and produce nuts. Production and growth will be below 1200 lbs to the acre. With such low production it makes chestnuts a poor selection for commercial production. Any cultivar with chinese (Castanea mollissima) genetics is likely to die or just a few inches a year, resulting is a small bush instead of a tree.

The Other Seasons Want to Kill Chestnut Trees Too
Aside from the flooding mentioned in the clay soil section above, winter can kill chestnut trees too. Depending on how severe the winters are in your area will effect the chestnut trees. Winter hardiness as it is called, depends on the cultivar. In general, for most the United States chestnut trees are winter hardy enough to survive just about anything winter can throw at it. During winter, when it is very cold and clear, the sun can warm the bark on the chestnut tree to the point where the sap starts to flow. Then with the sun sets the sap refreeze and damages the tissues under the bark. This freezing and thawing damages the trees and the trees are left with perminant damage called sun scald.

Winters can kill a chestnut tree if its too cold. How cold is too cold? It depends on the type or cultivar. Chinese chestnut (Castanea mollissima) trees can take almost anything winter has to offer, even temperatures below -20 degrees. The European cultivars can not take the cold as well. If the temperature drops below -10 then the European cultivars could suffer significant freezing damage, possibly even killing the chestnut trees. At 0 degrees some European cultivars will have freeze damage at the tips of branches but usually will not kill the tree. Photo 2 is a dead chestnut tree that died during the winter and is now dried out causing the open cracks at the bark ridge.

Early spring is the next season and potentially the season that kills more chestnut trees than any other. The two primary hazards are hard frosts after the chestnut trees start to bud out and water saturated soils. The key to both of these is if the chestnut tree has broken out of dormancy. Once a chestnut tree starts growing in the spring both hazards become potential killers. Just because a hard freeze comes along and kills the buds (Photo 5), it does not mean the tree will die. If the chestnut tree was stressed because of something else then its chances of surviving are much lower.

The second hazard for chestnut trees in the spring is water saturated soils. Water saturated soils can kill a chestnut tree just about any time a chestnut tree is actively growing. If you want to kill a chestnut tree without using herbicides, then just water it during the summer time to the point the ground is saturated 12" down and the soil makes a squish-squish sound when you walk across it.

Pathogons - Bugs that Kill Trees
There are a number of pathegons that can kill chestnut trees. Around the world there are several pathegons kill the old growth chestnut trees. On the top of the list is chestnut blight. Chestnut blight appears to harm and kill chestnut trees once the tree starts producing nuts - usually 4-6 years old. Chestnut blight appears as an orange canker on the bark of the tree. In a few years the infected chestnut tree will be dead.

Another top killer of chestnut trees is root rot. Root rot is more of a problem when chestnut trees are planted in heavier soils. The first sign a chestnut tree has root rot is the new leaves never get full size. Existing leaves will start to brown at the edges. Then all the leaves will turn brown and the tree dies. When a chestnut tree with root rot is dug up, the roots will present weak and rotting roots and the small white fiberous roots will be completely absent.

If you have a chestnut tree that is more bothersome than you like, this section gives most the answers on how to kill the trouble tree. If you have a chestnut tree you were hoping to save, this section should help you determine if the tree's long term survival is possible. If you were thinking of planting some chesnut trees, this section could help you save yourself a lot of lost effort and money.

Successfully growing chestnut trees is dependent on many factors. When selecting a site for growing chesnut trees, a pilot hole can help determine the soil and subsoil structures. A chestnut grower also needs to know what pathegons are present in the area. Carefull selection of the chestnut cultivar can be a big part of growing great chestnuts. See photo 3 for the two year old bark color of a healthy chestnut tree.

The Cold Growing Season Effect
Traditionally chestnut growers greatest fears for the growing season was high winds, late spring frosts, and drought. With these three risks you would think, "What else could go wrong?". The problem with this question is that it is so open ended. In keeping with the tradition of growing anything, you are mostly at the whims of nature. A cold growing season by itself is not a problem with chestnut production, at issue is when and how cold were specific parts of the growing season. To better understand how temps effect chestnut production the ag community has developed the Growing Degree Days (GDD) measurement. This web page provides some great details of the issues of GDD and chestnut production:
Chestnuts and Their Dependence on Growing Degree Days

The research field at Washington Chestnut Farm consists of 35 trees and several hundred linear feet of propagation beds. There are 11 different cultivars of chestnuts in the research field. All of the cultivars are hybrid European chestnuts. Many of the cultivars are represented by just one tree.

The goal of the research field is to demonstrate the effectiveness of chestnut cultivars in Northwest Washington State. The focus cultivar is the Colossal. Most commercial growers on the West Coast of the USA grow the Colossal cultivar. Of the 35 trees in the recearch field 12 are Colossals.

The growing season in 2008 was the coldest on record (records go back to the 1850's). Coldest needs to be quantified. Coldest is quantified by observing the average day time high temperature. During most of the growing season of 2008, the average day time high temperature was between 53 and 60 degrees F. Most any home gardener knows most plants in the garden needs at least 55 degrees F to grow.

Chestnut tree growing requirements are much like most garden plants, they need warm days to grow. On a good year chestnuts can grow 4 feet or more in a single growing season. In 2008 the average growth on the Colossal cultivar trees was about 16 inches. The cold also effected the grafts on newly grafted trees. Very few grafting attempts took. In addition, many of the chestnut trees did not set nuts. Most trees had a normal set of burrs, but almost all the nuts were without kernels. Some cultivars such as Basalta #3 produced good nuts with the exception of few burrs were set.

Maravals, like the Colossals, set heavy with burrs but most nuts were blanks. The Maraval nuts that did develop kernels were small and had no commercial value.

Aside from the Basalta #3, Marigoule chestnut trees produced full size nuts. The nuts are of excellent flavor and texture.

Two other cultivars are worth mentioning, Precoce Migoule and Okie. Okie chestnut trees have only been in part of the orchard for 2 years. Most of the Okie trees bloomed, none set burrs. The growth of the Okie was less than normal. Precoce Migoule trees had close to normal growth but nuts were almost all blanks.

Chestnut trees, like most green growing plants, do best where the growing season is warm. Washington Chestnut Company's farm is located about 10 miles south of the 49th parallel in Washington State. From obesrved performance during the the 2008 growing season, the following can be issues growers may need to consider:

1. Most chestnut cultivars set nuts poorly if day time high temperatures during pollination are below 60 degrees F.

2. Some chestnut cultivars require day time temperatures to be above 80 degrees F and night time temperatures staying above 60 degrees F to make good growth.

This is observable on the new growth of the established trees and even more so with 1 - 2 year old trees. Young chestnut trees can grow 36 - 42 inches a year for the first 3 to 4 years.

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