My crabapple flowers beautifully every spring and then in July it starts dropping its leaves and is almost completely bare by August. What’s wrong?
It is most likely showing the effects of Apple Scab. In this area of the United States, apple scab is the most common leaf disease of flowering crabapples. Although apple scab doesn’t kill the tree, year after year of early defoliation can weaken it. The early leaf drop removes food producing leaves and without proper food production the tree can become weak and more susceptible to other problems such as stem cankers and boring insects. Apple scab is a fungal disease. The fungal spores overwinter on the dead leaves, then when it rains in early spring and the temperature increases to above 40 degrees the spores become active and reinfect the tree. The wind can also disperse spores for many miles.
If you have a tree that is, year after year, defoliated by apple scab your best option may be to remove the tree and replace it with an apple scab resistant or tolerant variety (See the list of disease resistant and tolerant trees below). If this is not a viable option then you can try to minimize the overwintering of the fungal spores on the dead leaves by raking and removing the leaf debris from around the base of the tree each year. Be sure to rake the leaves before they become dry and brittle – and hard to rake without breaking apart. Unfortunately removing the leaf debris, by itself, is usually not effective enough to significantly reduce the amount of apple scab. Finally, you can contact a professional tree service and make the investment to have your tree begin a protective spray program. We typically recommend that a professional tree service be used because in order to be effective, a spray program usually involves 2-3 fungicide treatments during the early spring.
Don’t give up on flowering crabapples because of their sensitivity to apple scab. They are wonderful trees. By choosing disease resistant varieties you can have gorgeous flowers in spring and healthy foliage all season.
Some Great Ornamental Crabapples for Wisconsin:
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White Flowers
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| Adirondak |
Malus 'Adirondak' |
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| Beverly |
Malus 'Beverly' |
| Birdland |
Malus 'Beverly' |
| Bob White |
Malus 'Bob White' |
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| Coral Cascade |
Malus 'Coral Cascade' |
| Donald Wyman |
Malus 'Donald Wyman' |
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| Firebird® |
Malus sargentii 'Select A' PP12621 |
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| Golden Raindrops® |
Malus 'Golden Raindrops®' |
| Harvest Gold® |
Malus 'Harvest Gold®' |
| Homestead Hollow |
Malus 'Homestead Hollow' |
| Jack Siberian |
Malus baccata ‘Jacki’ |
| Mary Potter |
Malus 'Mary Potter' |
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| Red Jewel® |
Malus 'Red Jewel®' |
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| Redbud Crabapple |
Malus x zumi calocarpa |
| Sargent Crabapple |
Malus sargentii |
| Sugar Tyme® |
Malus 'Sugar Tyme®' |
| Tina Sargent |
Malus sargentii 'Tina' |
| Whitnall Yellow Zumi |
Malus 'Whitnall Yellow Zumi' |
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Soft Pink Flowers
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| Coralburst® |
Malus 'Coralburst®' |
| Japanese |
Malus floribunda |
| Louisa |
Malus 'Louisa' |
| Sentinel |
Malus 'Sentinel' |
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Deep Pink Flowers
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| Adams |
Malus 'Adams' |
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| Cardinal |
Malus hupensis 'Cardinal' |
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| Liset |
Malus 'Liset' |
| Mt. Arbor Special |
Malus 'Mt. Arbor Special' |
| Prairifire |
Malus 'Prairifire' |
| Profusion |
Malus 'Profusion' |
| Purple Prince |
Malus 'Purple Prince' |
| Royal Raindrops |
Malus 'Royal Raindrops' |
| Selkirk |
Malus 'Selkirk' |
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Small Scale – Dwarf Form (Under 15’)
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| Camelot® |
Malus 'Camelot®' |
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| Candymint |
Malus sargentii 'Candymint' |
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| Cinderella® |
Malus 'Cinderella®' |
| Coralburst™ |
Malus 'Coralburst™' |
| Firebird® |
Malus 'Firebird®' |
| Lancelot® |
Malus 'Lancelot®' |
| Lollipop™ |
Malus 'Lollipop™' |
| Royal Gem™ |
Malus 'Royal Gem™' |
| Tina |
Malus sargentii 'Tina' |
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