Ragweed and Sooty Blotch of Apple
By John Fulton

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[August 29, 2014]  Itchy Eyes and Scratchy Throat? - If you’re one that usually suffers from the fall allergy season, you know the symptoms all to well. Many people blame goldenrod as the culprit, when it is mostly ragweed problems.

In our area, we have two types of ragweed. The most noticeable is giant ragweed. Giant ragweed, also called horseweed, and it can grow well over 10 feet tall. It is very noticeable as one of the few weeds that grows taller than our Illinois corn. The other type of ragweed is common ragweed. It is generally less than six feet tall, and not nearly as noticeable.

Ragweeds tend to bloom in late summer. The period can range from mid-August to mid-September. They put out a lot of pollen when they bloom. The amount of pollen is one problem, but the shape of the pollen is the other. The shape of the pollen is more jagged and sharp along the edges, making it more of an irritant than other types of pollen.

Add in the usual ragweed problems, alternating wet and dry conditions, and early leaf drop, and we have the recipe for an allergy sufferer’s nightmare. There are also several leaf molds that are at work, and that compounds the allergy problem.

What can you do? First, try to eliminate ragweed in your particular area. Two, avoid the mid to late morning period in the great outdoors. This is when more pollen is released. Three, you can stay indoors (or office or car) with air conditioning. And, if your problems are particularly troublesome, talk to your doctor. There are prescriptions and over-the-counter that can help alleviate at least some of the symptoms. My doctor told me this week this particular season was the latest in the “worst ever.” At least, there is the old statement of “misery loves company” and you’re not alone.

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Sooty Blotch of Apple

Apple development seems to be running ahead of normal this year. Sooty blotch and flyspeck are caused by different fungi that commonly occur together on the same fruit. The sooty blotch fungus causes surface discoloration with black spots or blotches which can be a fourth of an inch or larger. These spots may run together, making the apple appear to be covered with something like charcoal dust. This disease is more superficial than anything, since it is only on the skin. Vigorous rubbing, or scrubbing, will remove the black discoloration. If you want to be sure, you can always peel the apples. 

This disease is most common with moderate temperatures and wet weather. Wet weather can include heavy dews which don’t get dried out very well. Anything that cuts down on air circulation helps promote sooty blotch. Pruning and thinning fruit will help improve air circulation, and lessen the disease problems.

The best chemical control program is to use a multi-purpose fruit tree spray, containing captan fungicide, as a preventative. For this disease, it is recommended to begin by early June, and continue the program until harvest. For the organic gardeners, sulfur will help some. However, it is not as good as the captan. Remember many diseases are preventable in home fruit production, but they are not curable. Once you see the problem, it becomes a to-do list item for next year.



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