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June beetles can damage plants this time of year

Early Saturday morning, I spotted two green beetles on a young apple tree. These are close relatives of what we called in the Midwest “June beetles.”

The green, metallic June beetles are more common here than the brown June beetles in the Midwest. They both can do a lot of damage.

June beetles make an immature form that doesn’t look like a beetle at all but more like a worm or a grub. We would call these “white grubs” or just plain grubs.

People have reported them actively chomping on the soft, fleshy roots of lantana and other trees and shrubs. They also can be seen chomping on roots of some of our lawn grasses.

As adults, they feed on soft fruit, particularly fresh figs, preferring the yellow or white types, such as Kadota, over the purple or brown types. They also will attack any soft fruit such as peaches or apricots if fruits are soft and ready to harvest.

There is no need to spray. The adult form only lasts about three weeks and they’ll be gone. You can learn more about them on my blog or my YouTube posting.

Q: I want to plant a mixture of trees, shrubs, succulents, palms and agaves. What is the perfect mix for the planting area? I’m thinking of removing 10 to 12 inches of native soil and replacing it.

A: If your existing soil is not full of large rocks or caliche, you can use it to plant everything. But you must amend or mix it with compost. Blend an equal volume of compost and soil together. Sometimes the word “organics” is used instead of compost but compost is a high-quality organic soil amendment.

If you plan to import a soil already mixed, use this soil for planting everything if it has good drainage. The difference among your plants will be how deeply the soil is prepared at planting, how often plants are irrigated and how often compost is added, if at all, in the future.

Make sure the soil on your property drains water. Dig 1-foot deep holes in three locations on the property. Fill them to the top with water. After two or three hours fill them to the top again.

The holes should be empty in 24 hours to be borderline satisfactory when it comes to drainage. When compost is mixed with the soil, water should drain away from the roots faster.

Dig planting holes the same depth as their container. Amend the soil surrounding the plants with compost a distance three times the width of the container. For large trees and shrubs, the soil should be amended 18 to 24 inches deep with compost. The soil for medium to small trees and shrubs, 12 to 18 inches deep.

Large agaves can be planted with this same soil and in the same manner used for large trees and shrubs. They have a similar rooting depth. Smaller agaves need soil preparation more like small trees and shrubs. Cacti and succulents require excellent water drainage from around the roots.

Lawns, as well as flower and vegetable beds, require about 12 inches of prepared soil. Prepared soil can be imported, or 2 inches of compost applied to the surface of the existing soil and mixed as deeply as possible. Vegetable and flower beds also require about 1 inch of compost added to them each year at planting time.

It’s your choice whether you want to bring in compost and amend the existing soil yourself or whether you want to import a soil mixture with compost already in it. Both are a lot of work. But you’ll have better success if you amend your soil with compost on-site and use it for planting.

Q: Some of my red yuccas planted last year are beginning to turn yellow a bit. Too much water?

A: Yellowing can be caused by poor soils, the soil not draining water fast enough, watering too often, intense sunlight and a few other less likely reasons. But these plants can take full sun if they are healthy. If you are watering daily, then I’m guessing it’s yellow because the roots aren’t getting a chance to breathe between waterings. Root suffocation.

Wait at least one day between irrigations. It’s best if the plant can wait two days but that depends on your situation. If this doesn’t solve the problem, then I’m guessing the soil needs to be improved this fall.

Q: I’m a new gardener and trying to grow a Table Mountain Delosperma in what was a 20-foot former dog run. I planted last summer, and I thought by now the whole area would be filled in, but that is not the case. I have patches that have grown but it’s still about 50 percent bare. It gets lots of sun, and I water by hand with a hose.

A: I had to look up that variety of ice plant since I didn’t know it. It was developed in Colorado, most likely for Colorado conditions, so it probably has pretty good tolerance to freezing weather.

Welcome to the Mojave Desert. Growing plants here that are not desert-adapted are much more difficult than growing them in other locations. The two biggest problems we have here are poor soils and proper irrigation.

I know I sound like a broken record sometimes, but soil improvement and having the right kind of irrigation is so important to this plant in our climate. Dog runs are not famous for being built on top of good soil. I am guessing the two problems you have with that plant is a lack of soil improvement and not having adequate irrigation.

There is no fertilizer or chemical additive that you can apply to the soil to improve it. It must be physically amended with organics, and I strongly suggest a good compost.

Around the middle of October, remove plants that are survivors and put them in a spot that will keep their roots moist and the plant in the shade.

Remove any rocks in the dog run larger than a pingpong ball to a depth of 12 inches. Apply about 2 inches of compost to the surface of the soil and turn the soil over twice. Make sure the compost is mixed thoroughly with that soil before planting. Rake and replant the ice plant with plenty of water from the hose.

Install a drip irrigation system for these plants with emitters on either side of the plant 6 inches away from the stem. The amount of water delivered by the drip emitters you select depends on how many minutes it will run. But select some that apply about 1 to 2 gallons of water each time you irrigate.

Since it’s the fall, water at least with one day between irrigations the first couple of weeks. As they get established and you see new growth, water less often.

Q: This spring I planted my fruit trees with compost mixed in the soil. My pomegranate tree is growing with dark green leaves, but it did not produce blooms. What have I done wrong? I water it frequently and yet no fruits are forming.

A: Both your pomegranate and nectarine tree have extremely dark leaves, are very full and growing by leaps and bounds. Thanks for the pictures.

That’s both a good thing and a bad thing; good thing because they are growing so rapidly and love what you’ve done but a bad thing because they are growing so rapidly they did not produce any flowers or fruit. They are focused on “vegetative” growth, not “reproductive” growth.

Don’t apply any fertilizer next year to either tree. Give the nutrients in the compost a chance to run out. This is very typical when plants get an abundance of nitrogen from compost. The same thing happens to tomato plants.

Remember, some composts have an abundance of nutrients while others don’t. Both types of composts are good for improving the soil but the compost you used has free fertilizer in it as well. You should see what that type of compost does to the leaf size of persimmons.

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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