Ash Tree Types, Facts, Care, and Diseases

Ash trees belong to a deciduous plant group that sheds leaves yearly. These are usually the sun-loving trees of medium to tall height (40-60 feet). All species of ash trees come under the order Lamiales, a family Oleaceae with the scientific name Fraxinus. These species are traditionally known as an olive family^[1]Karunarathna, A., et al., Patellariopsidaceae Fam. Nov. With Sexual-Asexual Connection and a New Host Record for Cheirospora botryospora (Vibrisseaceae, Ascomycota). Frontiers in Microbiology, 2020. … Continue reading.

Most of the lilac plant family and plants have been kept under this group. These deciduous trees have broad leaves and separate trees for the male and female sex.

These seeds specifically have such physiological appearance that made scientists name them like helicopter seeds. Fraxinus have distinctive and separate organisms (trees) for producing female and male gametes. This phenomenon is termed dioecy ^[2]Widrlechner, M.P., Building a comprehensive collection of ash germplasm. 2010..

The Fraxinus trees are mostly found in three continents Asia, Europe, and America especially, North American countries^[3]Maeda, M., et al., Phylogeny and taxonomy of Phyllactinia species (powdery mildew: Erysiphaceae) occurring on the ash trees (Fraxinus spp.). Mycoscience, 2021. 62(4): p. 268-280.. There is a long period in the life of these trees where they only behave as unisexual organisms.

Later on, these may develop male characteristics leading to femaleness for the development of seeds and fruits. Samara is the name given to the fruits of Fraxinus plants^[4]Wallander, E., Systematics of Fraxinus (Oleaceae) and evolution of dioecy. Plant Systematics and Evolution, 2008. 273(1): p. 25-49..

For visual identification of ash trees, two things are prominent to observe, first its opposite branching pattern and second its compound leaf structure.

Types of Ash trees (Fraxinus)

There are several types of ash trees.

1. Green Ash tree (Fraxinus pennsylvanica)

Among the most commonly found ash trees green ash is the prominent woody tree. Several other local names are also there for green ash such as red and water ash etc. These are the common shading trees of streets in Canada, Eastern America, and the US with the ability to withstand their growth in different kinds of soils^[5]Hinsinger, D.D., et al., The phylogeny and biogeographic history of ashes (Fraxinus, Oleaceae) highlight the roles of migration and vicariance in the diversification of temperate trees. PloS One, … Continue reading.

The attack of arthropod insect parasites can diminish the GDP of wood obtained from these green ash trees. These trees can be 50 to 70 feet tall.

2. California Ash tree (Fraxinus dipetala)

The local name two petal ash is given to this shrubby plant. This type of ash tree has a small size with less woody and shrubbier appearance in general. Its compound leaf has saw-tooth or zigzag edges.

It requires full sun to grow and it does not grow taller than 20 feet. Another specificity of California ash is its sweet fragrant petal clusters^[6]Hinsinger, D.D., et al., The phylogeny and biogeographic history of ashes (Fraxinus, Oleaceae) highlight the roles of migration and vicariance in the diversification of temperate trees. PloS One, … Continue reading.

As the name suggests it is commonly found in Arizona and California. There is great drought resistance found in California ash trees which perhaps be the reason for being away from ash borer insects.

3. White Ash tree (Fraxinus Americana)

As the name suggests this is found in Northern American countries. This tree has a thick canopy and tallest (70 to 80 feet) and is the most common tree in American regions. These trees have thick and dark bark with weird diamond-shaped outgrowths.

This is the most susceptible ash tree among the attacks of ash bore insects. They have 5 to 9 leaflets in their compound leaf^[7]Rebek, E.J., D.A. Herms, and D.R. Smitley, Interspecific variation in resistance to emerald ash borer (Coleoptera: Buprestidae) among North American and Asian ash (Fraxinus spp.). Environmental … Continue reading.

4. Black Ash tree (Fraxinus nigra)

In the regions of relatively cold climates such as Eastern Canada and the US, black ash is found. This is the nesting place of most bird species having 40 to 60 feet in height. Many animals eat its seeds and even branches are also consumed by herbivore animals.

At the same time, this species is also facing severe attacks of ash borer. Further plantation of black ash is not promoted by local agricultural and forest management departments ^[8]Erdmann, G.G., Managing black ash in the Lake States. Vol. 115. 1987: US Department of Agriculture, Forest Service, North Central Forest ….^[9]Tanis, S.R. and D.G. McCullough, Differential persistence of blue ash and white ash following emerald ash borer invasion. Canadian Journal of Forest Research, 2012. 42(8): p. 1542-1550..

5. Blue Ash tree (Fraxinus quadrangulata)

The reason for giving the name blue ash was its inner bark color. Whenever the inner bark is exposed to air it turns its color to blue. In past years it was used as a drying agent. This type is also resistant to drought^[10]Ladiges, P.Y., S.M. Prober, and G. Nelson, Cladistic and Biogeographic Analysis of the “Blue Ash’Eucalypts. Cladistics, 1992. 8(2): p. 103-124..

6. Manna Ash tree (Fraxinus ornus)

The important characteristic of this group is the release of sweet sap. Different carbohydrates and other derivatives can be extracted from the sap secreted by this species. This can grow 40 to 60 feet tall.

Researchers have described it as more resistant against ash borer. Before leaf fall the leaflets (5 to 9 with zigzag edges) turn yellow. This species is native to Asian and European countries^[11]Paoletti, E., et al., Structural and physiological responses to ozone in Manna ash (Fraxinus ornus L.) leaves of seedlings and mature trees under controlled and ambient conditions. Science of the … Continue reading.

7. Carolina Ash tree (Fraxinus caroliniana)

Damp and moisture-loving species of Fraxinus prefer low temperatures for growth. The other common name is water ash. It is found mostly in Carolina state and its neighboring countries.

This has 5 to 7 leaflets in its compound leaf and grows in shady areas while most of the ash tree species love sun exposure. The size of Carolina Ash is also smaller as compared to others (30 to 40 feet)^[12]Vengosh, A., et al., Evidence for unmonitored coal ash spills in Sutton Lake, North Carolina: Implications for contamination of lake ecosystems. Science of the total environment, 2019. 686: p. … Continue reading.

8. European Ash tree (Fraxinus excelsior)

The distinctive property of the European Ash tree is its compound leaves having 13 or more leaflets. It is also resistant to the attack of ash borer and 60 to 80 feet tall or above.

Another reason for its quick identification is the nature of its bark having brown buds instead of traditional black buds. As per indication by name, it is mostly native to European countries^[13]Dobrowolska, D., et al., A review of European ash (Fraxinus excelsior L.): implications for silviculture. Forestry, 2011. 84(2): p. 133-148..

Facts about Ash trees

1. They can be the size of a small shrub and tall up to 120 feet.
2. Young ash trees have bark with a smooth surface and grayish.
3. They have an extensive, thick, deep, and strong root and vascular system.
4. Wind plays the role of pollination between male and female flowers present on different trees.
5. Stomach disorders are being cured by a substance secreted by ash trees similar to olive oil.
6. The life of an ash tree can be between 30 to 300 years.
7. Its wood is used in making musical instruments and furniture and firewood are also obtained.
8. These seeds are called keys and are sometimes termed helicopter seeds.
9. The fruit’s name is Samara.
10. They are planted as street trees for shades as well^[14]James, M.R. and D. Collings, The Ash-tree. 1963: Royal National Institute for the Blind.^[15]Hunnicutt, R.E., Emerald ash borer adult feeding behavior, and ash tree management decision modeling: relationships between pest and host tolerance gradients. 2013, Purdue University..

Diseases of Ash trees

1. Three major arthropod insects are the main loss in the production of ash tree wood and its resins. These are
   1.1 Emerald Ash Borer
   1.2 Banded Ash Borer
   1.3 Leaf-curl Ash Aphid
   Both beetles and wasps take the nutrients away from the trunk branches and collectively damage the whole plant until it dies. Both of them weaken the stems and suck the phloem full of nutrients. That results in the collapse of a healthy tree^[16]Family Buprestidaet, A., Emerald Ash Borer, Agrilus planipennis..
2. Another big issue is gall formation which is an abnormal cluster growth on the plant which is triggered by a small mite named Eriophyid^[17]Eissfeller, V., et al., Tree identity surpasses tree diversity in affecting the community structure of oribatid mites (Oribatida) of deciduous temperate forests. Soil Biology and Biochemistry, 2013. … Continue reading.
3. Ash tree leaflets are susceptible to the attack of several nymphs and bugs. They destroy small leaflets resulting in a thin canopy for some time^[18]Caterpillar, E.T. and J. Beetles, Common Bad Bugs..
4. A situation termed Oystershell Scales is a condition in which Lepidosaphes ulmi attack the bark of an ash tree to make cracks in it^[19]Cranshaw, W.S., Oystershell scale. 1996, Colorado State University. Libraries..
5. An infection caused by the fungus Verticillium Wilt in which wilting of the leaf occurs ultimately when leaves are not there for food production branching stem will also die back^[20]Goldberg, N., Verticillium wilt. Compendium of pepper diseases. The American Phytopathological Society Press. St. Paul, Minnesota, 2003: p. 21-22..
6. Foliage-damaging fungal disease is called anthracnose of ash. In this disease, a very heavy leaf fall occurs decreasing the canopy abruptly.
7. A microbe Phytoplasma and rust-causing fungus Puccinia sparganioides lead to yellowing of leaves before defoliation and rusty orange and pale yellow spots on leaves affecting the capacity of photosynthesis respectively^[21]Amusa, N., et al., Guava fruit anthracnose and the effects on its nutritional and market values in Ibadan, Nigeria. World Journal of Agricultural Sciences, 2005. 1(2): p. 169-172..

Care of Ash Tree

To avoid the insect attack on ash plants spray proper insecticide before the egg hatching season of insects. All insect species have a certain time of the reproduction cycle. Proper check and balance are necessary to avoid mass loss due to arthropod parasites.

Proper watering is necessary. One can add fertilizers as well to enhance the nutrient level in the soil. Proper pruning and application of fungicides are also helpful in this context. Proper water is needed in the starting life span of an ash tree to promote the growth of extensive roots in the soil^[22]Gninenko, Y.I. and M. Klyukin, Nature itself took care of the ash-tree protection. Zashchita i Karantin Rasteniĭ, 2019(8): p. 42-43..

Mites and beetle-damaging foliage must be destroyed within their eggs before hatching. Pruning can also decrease the spread of the microbial disease yellow leaf of Ash trees. The damaged part is pruned to prevent the further spread of the infectious agent.

The decaying and damaged part of the infected tree must be removed from the nearby area of a tree because it can cause repeated infections and spread.

If proper watering, application of insecticide, and fungicides are done along with soil clearance and pruning we can have healthy growing trees^[23]Vannatta, A., R. Hauer, and N. Schuettpelz, Economic analysis of emerald ash borer (Coleoptera: Buprestidae) management options. Journal of Economic Entomology, 2012. 105(1): p. 196-206..