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Worms in apples? Codling moth is common pest

Q: I have had wormy apples in my Honeycrisp apple tree. Last year, I had the same problem. I was told to spray a fungicide. I also sprayed neem oil. I waited until the apples started to form. I still have these worms in every apple on my tree.

A: I am guessing that you are dealing with codling moth. This is a common pest of apples and pears. They appear as “wormy apples.” They are creamy white and about three-eighths of an inch long when they are mature. Usually, they have a brown head.

They start getting into the fruit when it is small and may continue to feed as it gets larger. You can read more about codling moth control by searching online for “codling moth” and “IPM” (Integrated Pest Management). The most reliable site is from the University of California.

If this is codling moth, then picking and getting rid of small, infested fruit is the first step. Otherwise, their population increases as the apple stays on the tree longer.

Apples that stay on the tree longest are the most heavily infested. On the flip side, apples harvested early are the least infested. Populations of this pest increase with each generation produced.

In our climate, expect codling moth to have three or four generations each year so start getting rid of infested fruit when the fruit is small. With each generation, the number of moths increases as the year progresses.

Start picking and getting rid of infested fruit about six weeks after it flowers. You can recognize infested fruit because of the brown frass coming out of it. The places where frass is coming from the fruit are called “stings.”

Stings are egg-laying sites by the female moth. Fruit that has frass coming from it will either fall from the tree or stay on the tree and get wormier. When you remove this fruit early, the population of worms has a better chance of staying low.

I have had good luck spraying either Bt or Spinosad several times over one season. Follow label directions.

I have also had good luck if I use pheromone traps and get rid of them using these traps. I use one trap for every three or four trees. Usually, pheromone traps are used for timing the application of sprays, but when populations are low, I have had good luck “trapping them out.” Those traps should be put in the trees when trees begin flowering or at least a couple of weeks after they start to flower.

Pheromone traps for codling moths can be bought from several places online. Look for them. The pheromone must be replaced regularly as per the instructions. Those wormy apples you got probably came from a neighbor who did not control them.

Q: I have some snails in my lawn. How do I get rid of them?

A: The best way to control snails (or slugs) in lawns is to give the lawn more light. Snails hate light but they like to eat. Snails and slugs eat young plants and microscopic plants such as algae.

The worst situation for snails and slugs is lawns growing under shade trees. The bigger and denser the tree gets, the more shade it produces.

In cases like that, get rid of the lawn — or both — but in the desert, never favor the lawn over the tree. A good-looking fescue lawn uses a lot more water than nearly any tree and usually requires daily applications of water in the summer.

Fescue lawns in the shade of a tree might still need 6 feet or more of water annually to look good. Many trees in full sun will need anywhere from 2 to 5 feet of water applied under their canopy. Xeric trees like acacia need less water than mesic trees like pistache or vitex.

There are baits made for snails and slugs. Those baits usually contain iron phosphate that is low in human toxicity. But it is a pesticide.

If you are into organics, then you might not want to use it. Your only options are to increase the light and trapping.

During times of high light levels, snails and slugs look for places to hide, so laying out boards or other places so they can hide during the day provides places where they collect. Their numbers can be reduced if you are willing to dispose of them after they collect under the boards.

Q: I was in Moab, Utah, when I ran across an apricot tree. It’s doing very well. I’m guessing the reason it is doing so well is because of the high organic levels in the soil and cooler temperatures.

A: You’re right. Fruit trees prefer to grow in soils with higher organics than most desert soils unless those desert soils were farmed and extra water was needed for farming.

Fruit trees also prefer to grow in cooler temperatures than those in hot deserts. At about 4,000 feet elevation, the Moab area is higher so it has cooler temperatures than our 2,000- to 3,000-foot elevations.

Growing of citrus, though, in either location, is borderline. Moab is still worse than our 2,000 feet of elevation. Neither place is like Yuma, Arizona, or Riverside, California, for citrus.

Q: Our vitex has done well for over 20 years, but it is starting to thin out. What gives?

A: Vitex, or monk’s pepper, is a mesic tree. It is from Mediterranean regions. But it doesn’t like poorly drained lawns. It can’t handle drainage problems well.

That may be the source of your problem with that tree. If the tree was planted in a low spot and, if all this rain added even more water to this low spot on top of your irrigations, then water-soaked roots during the heat may be the source of your problem. Summer heat is more of a problem than cold weather regarding rotting roots.

I was reading somewhere that vitex can be a short-lived tree. Twenty years was the maximum life it was given in this reference.

I don’t know if I agree, but you can winter prune it and extend its life. Trees, particularly small trees like vitex, can have an extended life by heavily pruning it in the winter. Many trees have a “root-to-shoot” ratio, and the new growth will come back like gangbusters until that old root-to-shoot ratio is reached.

Lightly fertilize it in the early spring with a fertilizer containing nutrients such as nitrogen.

Q: A local tree guide does not recommend planting Japanese blueberry because of “environmental challenges.” We had one at our old house and it was fine. It is the right size and shape for a spot we are considering.

A: There are some things that favor it and some things that are not in favor of it. Let’s explore:

Water use. In the desert, this should be a concern with any plant you are thinking about. The fewer plants the better. It is mesic in its water use. It should be watered at the same time as other mesic plants. Try not to water xeric plants at the same time as mesic plants. Xeric (or desert) plants are watered less often than mesic (nondesert) plants. That is one of the reasons xeric plants use less water.

Size. It’s slow growing but gets about the same size as European olive: 35 by 35 feet.

Location. It doesn’t like afternoon sun. It’s too hot on the south and west sides. The east side is better because of afternoon shade and surrounded by other plants that need watering. That and its mature size are probably the reasons it is not liked much.

Make sure this plant is placed in the shade of late afternoon, and make sure it is planted with lots of organics in the soil and receives regular watering.

Bob Morris is a horticulture expert and professor emeritus of the University of Nevada, Las Vegas. Visit his blog at xtremehorticulture.blogspot.com. Send questions to Extremehort@aol.com.

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