Leaf chlorosis is the result of mineral deficiencies, such as nitrogen, iron, or magnesium. Leaves turn yellow in response to nutrient shortages from poor soil (the problem can be made worse by overwatering, which leaches nutrients out of the soil). To check nutrient levels in your soil, perform a soil test.
Although there is no permanent cure other than removing the tree and planting something more adapted to our soils, treatments with chelated iron can be used to help alleviate the problem. Chelated iron with the formulation FeEDDHA should be applied to the entire yard around the tree every spring and watered in.
Many conditions can cause chlorosis in trees. The most common are various nutrient deficiencies, extreme pH levels or drought. Sometimes these conditions can combine to create more favorable conditions for chlorosis, and this past July's heat and drought may have contributed to an increase in these occurrences.
Brown leaf edges on maples and other trees are symptoms of scorch. This occurs when the tree loses water from its leaves faster than it can absorb it from the soil. Drought, windy conditions, and root damage or restrictions are often the cause.
Watering issues are generally the most common cause of yellowing leaves. When your plants are overwatered, the performance and vigor decrease. Oxygen is being pushed out of the soil, and the roots are simply “under aired” and suffocating. With little air, the roots will begin to drown and rot.
If it feels soft and limp, it is overwatered. Yellowing leaves: Usually accompanied by new growth falling, yellow leaves are an indication of overwatering. However, yellow, curling lower leaves can also be an indication of underwatering. Check the soil for moisture to decide which it may be.
Nutritional problems
Yellowing of the areas between the veins (interveinal chlorosis) is usually indicative of manganese, iron or magnesium deficiency. Iron deficiency affects the youngest leaves first, whereas the symptoms of manganese and magnesium deficiency tend to start in the older leaves.
All these trees can pretty much take the full sun to 85° without much problem. If it exceeds that – then morning sun and afternoon shade is important for successful growing of maples.
Maple trees need around 11 gallons of water a week to stay healthy, but young maple trees need even more, especially in dry, hot conditions. It's good to water your tree a few gallons every couple of days rather than a little every day.
Your soil should be cool and moist. If it's sopping wet, you're overwatering. If your soil isn't drenched or sandy, roll into a ball. If it crumbles, your tree needs more water.
The 'Princeton Gold' Norway maple naturally produces yellow leaves. Not all yellow leaves are due to a microelement deficiency. Trees may have yellowing leaves due to drought, flooding, aphids or any number of other stresses.
According to the University of Illinois Extension, a lack of iron either in the soil or available for uptake by the plant, is one of the more common reasons for chlorosis. Iron chlorosis will cause the leaves to turn from dark green to light green to yellow, but the veins on the leaves will remain green.
Most Japanese Maples will do well in a location with direct morning sun and shade in the afternoon. Hot afternoon summer sun exposure on many varieties of red Japanese Maples can result in sun burned leaves.
A yellow leaf has lost its chlorophyll (pigment) and it can't turn green again even after you correct the problem. Don't worry, if the plant regains its health, it's possible that new leaves will fill in during the next growing season. Growing plants is always a matter of patience.
Best Fertilizer For Maple
If not supporting organic practices, use Miracle-Gro® Tree & Shrub Plant Food Spikes. Per Miracle-Gro's directions, plant spikes in soft, moistened soil during the fall and spring. The NPK ratio of these spikes is 15-5-10.
If you are not sure whether or not your tree has been overwatered, there are a few other signs to look for. For example, leaves that are yellow or wilted can be a sign of too much water. You should also check for any fungal growths around the base of the tree. These are often indicative of overwatering as well.
The reason maple leaves turn brown on the edges in summer is that the tree is unable to replenish the moisture the foliage loses through natural transpiration. As moisture leaves a plant, the tree draws moisture up from the ground to keep the cells in the leaves healthy and robust.
The best way to water a tree is with soaker hoses or drip irrigation. Sprinklers are less efficient. Deep watering to a depth of 15 inches, once a week is ideal during the growing season when drought exists. Watering deeper wastes water.
WATER: During an excessive heat event, we recommend that you double your normal watering routine. This means that your new trees should receive 15 gallons of water at least twice a week throughout the heat wave, meaning a deep watering every three to four days when it's about 90-degrees or more for an extended period.
While some tree species are more tolerant than others to heat stress,. prolonged heat exposure can certainly exacerbate existing issues. At high temperatures and without sufficient water, trees eventually reach a point where they can't take up enough water from the soil to support the whole tree canopy.
Signs of Heat Stress in Trees
As the tree becomes more stressed, stems and branches can start to droop. Irregular yellowing of interior leaves or needles. Failure to produce healthy-looking new growth, making the tree canopy look sparse. Rust-colored spots or bumps on leaves.
Additionally, too much fertilizer can yellow leaves and is likely to prevent blooms and fruits from forming. Key indicators: Leaves might yellow and wilt. Other symptoms include root rot, stunted growth, leaf drop, or browning of leaf tips. There may also be a visible crust of fertilizer on the surface of the soil.
Nitrogen deficiency shows up as a general yellowing. Older, inner leaves turn yellow first. As it progresses, yellowing moves outward, eventually reaching young leaves, too. Potassium deficiency shows itself when leaf edges turn bright yellow, but the inner leaf stays green.