Royal Raindrop Crabtree having issues - Ask Extension
Hello. We are having issues with our Royal Raindrop Crabtree. It was around 8 feet when I planted it on the East side of our house in our rock garden ...
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Royal Raindrop Crabtree having issues #878368
Asked July 23, 2024, 7:40 AM EDT
Hello. We are having issues with our Royal Raindrop Crabtree. It was around 8 feet when I planted it on the East side of our house in our rock garden 4 years ago. It's leaves are in bad shape and we are seeing more splits on the trunk and branches along with spots.
We are in Byron Center, Mi.
Photos are attached.
Thank you!
Kent County Michigan
Expert Response
Hi Rick, Thank you for your inquiry.
Typically, crab apple trees are quite tough once established. They
thrive best in rich, moist, slightly acidic loam type soil with good
drainage and full sun exposure of 8 or more hours per day. Your variety is known to have good disease resistance to the most common afflictions of apple trees: fire blight, apple scab, apple rust, and powdery mildew but resistance is relative and doesn't mean the tree is immune to disease problems. Your tree is stressed as evidenced by its unhealthy appearance. This can be due to many factors: under or over watering, too much shade, insect damage, disease, and physical damage from things like lawn mowers, weed whips, animals, and so forth.
I do see one serious problem with your tree...It is planted too deep. Trees should be planted with the root flare, or where the trunk starts to develop roots, level or 1-2 inches above the level of the soil. Below are some reasons why trees should be planted at this depth.
1. When soil is placed around the bark of the tree, the trunk can start to rot from the moisture in the soil. Eventually, the tree will be unable to transport important minerals up the phloem
(the outside area of the tree) and become susceptible to disease and insect invasion through the soggy bark.
2. Trees roots need oxygen to develop and the soil closer to the ground level has more oxygen. When we plant trees at the correct depth, this mimics what happens naturally in nature after a seed sprouts and starts to grow. When the trees are planted too deep, the roots can have less exposure to the oxygen that exists at higher concentrations closer to the surface of the soil. This will stunt some of the roots growth and weaken the tree.
While I can't be 100% sure by merely looking at your pictures, my best guess is that your tree is infected with a fungal disease called apple scab. This disease occurs most often during moist conditions. Severely infected leaves turn yellow and drop prematurely, weakening the tree. Your tree's leaves are turning a darker color rather than yellow, perhaps because the healthy color of your tree leaves is deep purple rather than green.
Apple scab is a very common disease in our area. As with all fungal diseases, the fungal spores are disbursed by wind and rain/splashing water on the leaves. You may see entire neighborhoods with sickly crab apple trees for this reason.
Several years of early leaf loss can result in decreased growth, reduced bloom and increased susceptibility to winter injury.
Control of scab involves raking up and disposing of all fallen leaves. Do not compost! The fungal spores can overwinter on the fallen leaves, so this is a very important measure to take. Also
Also avoid overhead watering and make sure there is good air flow between your tree and other trees by properly spacing them and pruning them.
Sometimes fungicides are used but must be applied yearly early in the season to healthy leaves BEFORE any infection starts. Sprays will not "cure" the disease already present, so spraying this late in the season is not an effective measure. We do not recommend fertilizing trees in the fall or when they are stressed. Learn more about this disease and control options here:
http://www.extension.umn.edu/garden/yard-garden/trees-shrubs/managing-apple-scab/
https://www.canr.msu.edu/resources/apple_scab
Typically, crab apple trees are quite tough once established. They
thrive best in rich, moist, slightly acidic loam type soil with good
drainage and full sun exposure of 8 or more hours per day. Your variety is known to have good disease resistance to the most common afflictions of apple trees: fire blight, apple scab, apple rust, and powdery mildew but resistance is relative and doesn't mean the tree is immune to disease problems. Your tree is stressed as evidenced by its unhealthy appearance. This can be due to many factors: under or over watering, too much shade, insect damage, disease, and physical damage from things like lawn mowers, weed whips, animals, and so forth.
I do see one serious problem with your tree...It is planted too deep. Trees should be planted with the root flare, or where the trunk starts to develop roots, level or 1-2 inches above the level of the soil. Below are some reasons why trees should be planted at this depth.
1. When soil is placed around the bark of the tree, the trunk can start to rot from the moisture in the soil. Eventually, the tree will be unable to transport important minerals up the phloem
(the outside area of the tree) and become susceptible to disease and insect invasion through the soggy bark.
2. Trees roots need oxygen to develop and the soil closer to the ground level has more oxygen. When we plant trees at the correct depth, this mimics what happens naturally in nature after a seed sprouts and starts to grow. When the trees are planted too deep, the roots can have less exposure to the oxygen that exists at higher concentrations closer to the surface of the soil. This will stunt some of the roots growth and weaken the tree.
While I can't be 100% sure by merely looking at your pictures, my best guess is that your tree is infected with a fungal disease called apple scab. This disease occurs most often during moist conditions. Severely infected leaves turn yellow and drop prematurely, weakening the tree. Your tree's leaves are turning a darker color rather than yellow, perhaps because the healthy color of your tree leaves is deep purple rather than green.
Apple scab is a very common disease in our area. As with all fungal diseases, the fungal spores are disbursed by wind and rain/splashing water on the leaves. You may see entire neighborhoods with sickly crab apple trees for this reason.
Several years of early leaf loss can result in decreased growth, reduced bloom and increased susceptibility to winter injury.
Control of scab involves raking up and disposing of all fallen leaves. Do not compost! The fungal spores can overwinter on the fallen leaves, so this is a very important measure to take. Also
Also avoid overhead watering and make sure there is good air flow between your tree and other trees by properly spacing them and pruning them.
Sometimes fungicides are used but must be applied yearly early in the season to healthy leaves BEFORE any infection starts. Sprays will not "cure" the disease already present, so spraying this late in the season is not an effective measure. We do not recommend fertilizing trees in the fall or when they are stressed. Learn more about this disease and control options here:
http://www.extension.umn.edu/garden/yard-garden/trees-shrubs/managing-apple-scab/
https://www.canr.msu.edu/resources/apple_scab
