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Apple scab affects leaves and fruit of trees
Mark Flory, Agriculture Agent
Apple scab can be a problem. We have many people who enjoy growing and harvesting a variety of different fruits.
Even though we all enjoy the end product, sometimes we encounter diseases that threaten our fruit crop. I comment on a problem that is common in Miami County and throughout Kansas. This disease, apple scab, affects apple and crabapple trees and the fruit.
Apple scab presents such a problem because it can reproduce great numbers of spores from a very small original source. Even though a lot of the things mentioned about apple scab we do in the spring, I decided to write about apple scab because I have seen several samples this year with mature fruit that have been affected by it.
As we look at the life cycle of apple scab, which is caused by the fungus Venturia Inaequalis, it over-winters in the infected leaves fallen from the tree.
In the spring, the infected leaves release spores that are carried by wind and infect new leaves emerging from the apple trees. Generally, you can see signs of infection 10 to 14 days after the fungal spores have reached new leaves. The fungus will start to cause lesions on the upper and lower leaf structure.
The devastating part with apple scab is once the lesions are established in new leaves, they will actually produce a secondary spore called conidia that can re-infect either leaves or fruit throughout the summer.
So, as you can tell, apple scab can spread very profusely.
As far as actual damage apple scab causes, there are several ways it affects the tree. First, the lesions on leaves eventually will cause them to yellow and prematurely drop off the tree. Also, in early spring, the spores can infect new blossoms, causing blossom blight which will result in premature fruit dropping.
In addition, apple scab can infect mature fruit due to secondary spores released through the summer, causing dark brown and black spots on fruit.
For control measures, the first thing many of you have thought is to make sure you rake up all of the leaves in the fall, since you know the fungus over-winters in dead leaves. However even though this will help, generally raking the leaves alone is not enough to stop apple scab.
The second thing is a fungicidal spraying of the apple trees. This is generally done in the spring just before bloom, and then you will need to repeat the spraying every seven to 10 days.
If you have any questions about apple scab, please contact me at the Miami County Extension office, 294-4306.
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Apple scab can be a problem. We have many people who enjoy growing and harvesting a variety of different fruits.
Even though we all enjoy the end product, sometimes we encounter diseases that threaten our fruit crop. I comment on a problem that is common in Miami County and throughout Kansas. This disease, apple scab, affects apple and crabapple trees and the fruit.
Apple scab presents such a problem because it can reproduce great numbers of spores from a very small original source. Even though a lot of the things mentioned about apple scab we do in the spring, I decided to write about apple scab because I have seen several samples this year with mature fruit that have been affected by it.
As we look at the life cycle of apple scab, which is caused by the fungus Venturia Inaequalis, it over-winters in the infected leaves fallen from the tree.
In the spring, the infected leaves release spores that are carried by wind and infect new leaves emerging from the apple trees. Generally, you can see signs of infection 10 to 14 days after the fungal spores have reached new leaves. The fungus will start to cause lesions on the upper and lower leaf structure.
The devastating part with apple scab is once the lesions are established in new leaves, they will actually produce a secondary spore called conidia that can re-infect either leaves or fruit throughout the summer.
So, as you can tell, apple scab can spread very profusely.
As far as actual damage apple scab causes, there are several ways it affects the tree. First, the lesions on leaves eventually will cause them to yellow and prematurely drop off the tree. Also, in early spring, the spores can infect new blossoms, causing blossom blight which will result in premature fruit dropping.
In addition, apple scab can infect mature fruit due to secondary spores released through the summer, causing dark brown and black spots on fruit.
For control measures, the first thing many of you have thought is to make sure you rake up all of the leaves in the fall, since you know the fungus over-winters in dead leaves. However even though this will help, generally raking the leaves alone is not enough to stop apple scab.
The second thing is a fungicidal spraying of the apple trees. This is generally done in the spring just before bloom, and then you will need to repeat the spraying every seven to 10 days.
If you have any questions about apple scab, please contact me at the Miami County Extension office, 294-4306.