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Garden Help Desk: What’s going on with my golden delicious apples?

By USU Extension - | Nov 6, 2021
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When apples are exposed to direct, intense afternoon sun, the tissues can overheat and "cook" in the exposed spot. The rest of the apple is still good to eat, but it would spoil during storage, so trim and use sunscalded apples right away. (Courtesy photo)
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The apples on the west and southwest side of a tree can be scalded by intense summer sun if there isn't adequate foliage to protect them. Good tree care can improve leaf coverage and shade cloth or bagging the apples can provide temporary protection if needed. (Courtesy photo)

Something new happened with my golden delicious apples this year. Some of them have a slight pink blush on one side (usually the side facing the sun), which progresses from a smooth skin to a blistered skin, then on to a brown spot to a spoiled brown spot. The original pink coloration does not appear to go below the surface, but brown spot certainly does, as you can see in the picture. What is the cause of the pink stuff? Are the apples good to use?

This looks like sun scald. Direct summer sun on the skin of exposed apples can overheat and “cook” the tissues. They are safe to eat. Just trim away those damaged spots and use the apples.

Adequate canopy coverage can reduce the problem. Apple trees need to be pruned to keep them healthy, but over-pruning can reduce leaf coverage and expose fruit and thin bark to intense summer sun.

Sometimes, a tree has been properly pruned but leaf coverage is poor because of poor tree nutrition. Fruit trees need enough nitrogen for good leaf growth. If soil nitrogen is low, that can affect leaf coverage

Here are a couple of methods you can use to decide whether or how much nitrogen to give your tree.

You can check the shoot growth. If your tree was young and not bearing fruit yet, it should produce 12 to 18 inches of new growth on branches each year. An established, productive tree like yours should produce about 8 to 12 inches of new growth per year. Peaches will be more at 12 to 15 or 18 inches of new growth. If your trees are producing this amount of shoot growth, whatever nitrogen fertilizer they are getting is sufficient. If less, the trees will benefit from additional nitrogen. If more, the trees would benefit from less nitrogen.

Or, you can use the age of your tree as a guide. This little rule of thumb is to apply 1 ounce of actual nitrogen per year of tree age, but not more than 8 ounces per year. Apply the nitrogen in March. You’ll need to figure out how much actual nitrogen is the fertilizer you’re going to use. For example, if you bought ammonium sulfate (21-0-0), your product would be 20% (1/5) nitrogen. You would need to apply 5 times the amount of fertilizer product to get the right amount of actual nitrogen. So, you would apply 25 ounces, or about a pound and a half of fertilizer to a 5 yr. old tree.

Next year, apply nitrogen in the early spring if your tree needs it, don’t over-prune and consider providing some very light shade for the west-southwest side of your tree or bagging those apples, if there isn’t good leaf coverage.

Our lawn developed a spot early in the spring and it continued to spread during the summer. We thought it was lack of water, and started watering more frequently, but it didn’t help. Our lawn care service said it might be a virus. So, I turn to you for help.

A virus would be extremely unlikely. There are a few viruses that can infect certain warm-season grass species, but there are no viral lawn problems that we have seen with our cool-season grasses here in Utah County. I checked with our Utah Plant Pest Diagnostic Lab in Logan and there aren’t any known viral lawn diseases seen in any of our cool-season lawns.

It’s very difficult to do a lawn diagnosis with a just a photo, but from what I saw in your photo your lawn most likely has a fungal problem or an insect problem like grubs, webworms, billbugs, or possibly a pest like clover mites. At this time of year these pests would be difficult to find, but if you want to check, the best place to look for pests or active diseases in a lawn is at the margin between grass that looks good and grass that looks dead.


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