We purchased a new home and it has a city-planted maple tree. The circumference is ~14 inches.
It seems like the ends of the tree are turning yellow (chlorosis?) Some leaves are scorching up into a brown crisp. See the picture attached.
I probably water once a week or once every two weeks… do you think it’s enough? Do you think this is causing it? I don’t want to overwater it…
I read somewhere that the soil may be alkaline and need to make it more acidic to combat the chlorosis. Don’t know. Maybe it just needs more water. All the other trees on the street have a deep green color.
Thank you – very much appreciated :)
PS I can send more pictures via email.
Thank you for contacting the Toronto master gardeners concerning your yellowing maple tree. From your photo there could be a number of issues at play that are causing the yellowing leaves.
Watering is probably the most important aspect of ensuring the health of trees, both newly planted and well-established. Stress from drought makes trees more vulnerable to predations by insect pests and diseases. Drought conditions, i.e., very dry soil, can limit a tree’s ability to absorb water, and can cause smaller roots near the soil surface to die. It is important for tree roots to absorb water right up until the end of the fall. But how much is enough? And how do you know?
The following information if from of our earlier posts on the proper watering of established and newly planted trees:
“This is a good question, especially with the GTA weather over these summer months which has veered between frequent, heavy bursts of rainfall to periods of extreme heat and drought. Keeping an eye on the weather is something that homeowners should be doing in order to ensure the health of our gardens in general, and our trees, both mature and newly planted. Determining the amount of rainfall or irrigation necessary to satisfy a tree’s needs is a complex subject, and there are equations available for use by arborists and other tree professionals, but for the home gardener, there are some general rules that, if followed, should help to keep our trees healthy.
Experts agree that deeper, less frequent watering is better for trees than lighter, more frequent watering. We also know that when a tree is surrounded by a lawn, the turf will take up much of the water, leaving less for the deeper tree roots, so a longer period of deep watering will be helpful. This precept would apply to your neighbour’s European beech tree. The European beech, Fagus sylvatica L. is considered to be a drought-sensitive tree, so in the absence of a good rainfall (a slow, steady rain rather than a quick but torrential downpour), your neighbour should consider a weekly watering. The object is to water the roots of the tree, which is best done by running a hose slowly at soil level, at the drip line of the tree. The “drip line” is the term that describes the area of a tree’s canopy or crown as if drawn in a circle around the trunk of the tree: when you see images of a tree and its roots, you will notice that the roots spread underground much like a mirror image of the canopy above the ground. The outer edges of the tree’s roots are full of what are known as feeder rootlets, which are responsible for absorbing moisture and nutrients. If you use a low sprinkler, you can place a measuring cup or other straight-sided container under the sprinkler and water until the level in the cup has reached one to two inches. This is the equivalent of one to two inches of rain, which should penetrate the soil up to about six inches, and will reach these fine rootlets which are close to the surface of the soil. Some experts recommend longer soaking which will go into the soil to a greater depth, especially for well-established trees.
Newly planted young trees, whose root systems are still developing, should receive regular watering, not only at the drip line, but also right around the trunk so that the root ball is well irrigated. Some experts recommend watering every couple of days, depending upon the weather. Others suggest a weekly watering for as long as two or three years, while the tree develops a strong root system. Transplanted older, large trees can experience significant stress from drought as well as from transplanting, and the nursery where they were purchased should advise here. You may have noticed some of the newly planted city trees use root bags, which are a good way of delivering the right amount of irrigation. Nurseries will be able to tell you whether your new tree is sensitive to drought. Japanese maples, dogwoods, birches, and hydrangeas are all considered drought-sensitive. Mulch, properly applied (that is, a layer of a couple of inches, in a circle several inches from the trunk of the tree) helps to retain moisture in the soil.
Here are a couple of websites which provide some useful information:
On irrigation of trees generally:https://www.mortonarb.org/trees-plants/tree-and-plant-advice/horticulture-care/watering-trees-and-shrubs
On the specifics of watering young trees: https://www.extension.umn.edu/garden/yard-garden/trees-shrubs/watering-new-trees-shrubs/ “
Now onto your yellowing leaves: while it might not be ‘normal’ for leaves to become yellow in mid-summer, it’s most likely that weather conditions this summer have played a role. The yellowing of the leaves is a form of chlorosis, which can be caused by extreme fluctuations in temperatures compounded by long periods of minimal or no rain–all of which we experienced for a period of time this summer.
Looking at your photo it appears that your leaves could be suffering from interveinal chlorosis. A condition where the veins appear green and the tissue between the veins is yellow. The yellowing that you are seeing is actually due to a lack of uptake of manganese and/or iron in alkaline soil, soils that have a pH higher than 7.0, predominant in the Toronto area. Even though these micro-nutrients may be present in the soil, the tree is unable to absorb them. Iron is necessary for the formation of chlorophyll, which is responsible for the green color in plants and is a source of plant food and energy. When the amount of iron available to plants is inadequate for normal growth, leaves become pale green, yellow or eventually brown and die.
Soil has a natural buffering capacity, and adding an acidifier to reduce the pH will work for a short time, however unless the soil is constantly amended it will revert back to it’s natural pH. Having your soil tested is a great step to understanding what you are working with. You should be able to determine the nutrients you have as well at the pH of your soil. We recommend the City of Toronto’s Guide for Soil Testing in Urban Gardens, which outlines a step-by-step process you can follow. Click here to read or print it. The University of Guelph’s Agriculture and Food Laboratory information can be found here.
If you do determine that the chlorosis is due to a lack of iron or magnesium uptake then you can add chelated forms of iron available at your local garden centre. A chelating agent is a synthetic organic substance that can maintain iron (as well as copper, manganese and zinc) in a nonionized, water-soluble form that is readily absorbed by plants. Make sure to follow the dilution directions on the package before adding to the soil. You may be interested in reading the article from Utah State University Forestry Extension titled: Preventing and Treating Iron Chlorosis in Trees and Shrubs