- Though not a prevalent wood used in the United States, the horse chestnut tree is a more common used source of lumber in Europe.  It is used predominately for veneer, furniture and plywood.  The creamy yellowish brown color of the wood, the ease of working with and finishing it all contribute to this use.  However, the wood is non-durable, the grains are not straight, and the resulting lumber is not particularly strong. 

  Ornamental landscaping - Aesculus Hippocastanum trees are incredibly aesthetically pleasant.  They have large white flowers that are accented with yellow and red centers.  The tree itself is impressively sized and can become very full. These characteristics allowed the Horse Chestnut to spread throughout the Northern Hemisphere.  People began to cultivate these trees to be placed throughout their communities and homes.  They are very often found in parks, gardens, estates, residential areas, golf courses, and on campuses.  For more on their distribution, see Habitat.
    Entertainment -
In the Village Green at Ashton in Northamptonshire on the second Sunday in October, the World Conker Championships are heldConker is another name for the seeds of a horse chestnut tree, specifically when used to play the game "Conkers/Kingers."  In the fall, fruit of the horse chestnut will ripen, the outer spiny casing will reveal the contained conkers, and the fruit will fall from the tree.  People then select the uncracked, hard, and symmetrical seeds and drill a hole in the middle to attach to a 25 cm (approx. 10 in) long string.  Also while selecting for the best conkers, people will test to see if they float.  If they do it means that they probably have sustained damage inside to account for the lack of density.  One participant wraps part of the string around their hands and pull it back to strike the other's seed.  The opponent has to hold the conker completely still for the strike.  The players alternate strikes until one of the conkers is completely destroyed.  At this point this game seems rather simple, but that is completely decieving! If a player misses while attempting a strike, the opponent obtains two extra strikes.  If a string is tangled and the opponent calls "strings" they receive an extra strike.  If a conker is striked and completes a full circle, the player who just delivered that strike gets an additional strike.  Lastly, if a conker is dropped and the other player yells "stamps" they are allowed to jump on it, but if the player who dropped it yells "no stamps first" they can simply pick it back up!  On top of this, not only does this game have a complex scoring system, it also has a complex ranking system to keep track of the achievements and victories a "conker" has accomplished. 
    Health -
see Health & Horse Chestnuts.


Pseudomonas syringae pv. aesculi - The Pseudomonas syringae pv. aesculi is a Gram-negative rod-shaped bacteria which is a very significant pathogen to Horse Chestnut trees. Though this pathogen has apparently not reached the United States, it is present in a great percentage of European trees. In 2007 it was found that around 49%of Horse Chestnut trees in the United Kingdom were infected by P. syringae and about 30% were infected in the Netherlands. Early on in the infection trees will display red, yellow or black bleeding lesions located at the base of the tree.  As the infection progresses the lesions expand upwards.  Trees can also start to display leaf discoloration, early leaf drop, cracked or missing bark, and eventually even girdling.  This bacterium has been shown to invade the trunks, branches, leaves, flowers and fruits.  However, it seems unable to be transmitted through the seeds. 

    The Animal and Plant Health Inspection Service (APHIS) issued a federal order effective beginning on January 25, 2010 that stopped importation of any trees for planting of the Aesculus genus from any country, except Canada.  These extreme measures had to be taken as plant pathogens like P. syringae are very hard to find in simple inspections at time of importation.  Even if an infection is recognized, the infection of Horse Chestnut by P. syringae has been often misdiagnosed as infection by Phytophthora sp.  See Phytophtora sp. lower on this page.

Cameraria ohridella(Horse Chestnut Leaf Miner) - The Horse Chestnut Leaf Miner appeared to human knowledge for the first time in 1984 in Macedonia and has since spread all over Europe. 
It takes very little time, respectively for these insects to establish in significant numbers as they can generate about 3 complete generations in a single year. The C. ohridella also has a very small number of effective natural predators/threats.  This assists them in their rapid spread and increase in population. As can be logically reasoned from this species of insect's name, Aesculus Hippocastanum are very important hosts for their survival.  The larval form will mine through and feed on the trees.  This results in early leaf drop and a second flowering with fewer seeds. 

Though this infestation has not been seen to lead to any significant die-off of the trees, much time and resources have been put towards finding an efficient method to controlling this invasive pest.  In 2010 a paper titled "An attempt to control Cameraria ohridella using an attract-and-kill technique" was published summarizing previously tested methods and the results of an attract-and-kill method.  The paper first describes the most effective methods in place currently, which are the removal of leaf litter and spread of chemical insecticides on the leaves of the trees.  The developed "attract-and-kill" method consisted of attracting the male moths with sex pheromones and then killing them with a fast acting contact toxicant.  However, hopes for finding a more effective method were smashed when it was concluded that their specified method failed to prove effective.  The researchers utilized trap catches to quantify the insect population and even though these traps indicated that the populations in the treated areas were decreased, the damage to the horse chestnut leaves were not significantly different in treated vs. non-treated areas.  This was contributed to the mobility of the insects to migrate over large areas and the small size of the treated areas. 

Other pathogens/parasites -

    Powdery mildew is a term used for many different species of fungi that parasitize plants causing the appearance of a fuzzy white layer on the epidermis of leaves. In particular, the fungus Uncinula (Erysiphe) flexuosa is particularly known to act as a parasite on horse chestnut trees.  This ascomycota does not only attach to horse chestnuts as its range spreads from North America to Russia! To read about another organism with this same pathogen take a look at Salvia oficinales.

    The caterpillars of the whitemarked tussock moth commonly feed on the leaves of the horse chestnut tree.  These caterpillars use their mouth parts to either skeletonize the leaves or consume all of the leaf except for the major veins.  This depends on the age of the caterpillars.  However, they do not pose much of a serious threat to horse chestnut trees as a whole.
   The Japanese beetle can cause two different major groups of symptoms in horse chestnut trees.  As adults these beetles will cause holes in the leaves and as grubs they will cause discolorated and unhealthy patches.  In the adult stage these organisms display a metallic green color with bronze-colored wings.

    The bagworm, the larval stage of the moth Thyridopteryx ephemeraeformis, can feed on a huge variety of deciduous and evergreen trees.  These organism cleverly disguise themselves with leaves and twigs from the tree and therefore often avoid identification.

    The Asian longhorned beetle, Anoplophora glabripennis, is thought to have traveled from Asia to the United States in the 1990s on wood materials being transported.  This arthropod is identified by the white markings on its black body and antennae.  The host trees are used as a location for the eggs to be laid and hatched.  Once in larval form, these organisms feed on the vascular layer beneath the bark of the tree. 


One reason Aesculus hippocastanum are so desirable to have in an environment is the large impact they can have on local biodiversity and environmental health.  To start, because of the photosynthesis the horse chestnut undergoes, it contributes to the absorption of carbon dioxide and the production of oxygen.  In some locations the trees also allow for less use of energy consuming air conditioners by providing shade for surrounding buildings.  The roots can function to filter rain water, improving the quality of local water, and stabilize the surrounding soil. 

    For basic survival, all organisms need shelter, food and water.  The horse chestnut can provide these either directly or indirectly to organisms to support biodiversity and life.  A huge variety of birds and small animals use these trees for shelter.  In aquatic environments they are also able to provide shelter and/or habitat to the organisms.  Directly, the horse chestnut tree is used as a food source for many parasites including the previously discussed caterpillars, fungus, beetles, etc. The seeds are often eaten by deer and grazing animals.  However, eating this plant is not risk free for these animals.  See Health & Horse Chestnuts for more on the poisonous effects of the horse chestnut.  As far as providing water, horse chestnuts have the ability to alter the temperature of water through shade and filter rain water through its roots. 

    Allelopathic nature- The horse chestnut releases chemicals through the roots of the tree that can inhibit surrounding plant growth.  This gives the trees a competitive advantage for space and other resources.  The term allelopathy comes from allelon meaning "of each other" and pathos meaning "to suffer."  To explore more about Allelopathic chemicals and behaviors visit Allelopathic nature.
    Rat poison- All parts of the horse chestnut contain the toxin aesculin.  Even though the rat poison warfarin is directly created from clovers containing a similar toxin, aesculin from horse chestnuts was used to develop the poison.  For more on the effects of aesculin see Horse & Horse Chestnuts.
If you would like to read about a different organisms that "loves parasitic relationships," visit Xanthomonas campestris.

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