Proper irrigations crucial to palms’ survival

Q: Every year my zucchini plants are infested with gray-colored beetles that destroy my zucchini. How do I get rid of the beetles?

A: These are most likely squash bugs. You can plant late, in June, after their infestation time has passed or you can hand pick them as soon you see them. You must do this as they appear and get rid of them as soon as you see them. Do this for about three weeks and the numbers will be greatly reduced or eliminated.

You also can vacuum them with a handheld vacuum cleaner or use pesticides suitable for squash bugs. If you choose to spray, do not spray plants when they are in bloom. Also, spray very early in the morning or at sunset when bees are not active.

Q: We have a fan palm where the palms are turning yellow and I'm assuming dying. One or two would be acceptable but we are have five and six going bad.

A: These are the main reasons for fronds turning yellow or bronzing: Older fronds are dying from natural causes and should be removed; fronds were damaged during the winter freezes; too much water too often or too little water; planted too deeply; planted in heavy soil that doesn't drain well; planted with pure sand around the rootball; fertilizer problem such as iron, manganese or zinc; and possibly some others. Let's talk in some general terms. Palms should be planted in native soil and backfilled around the root system with the native soil plus 50 percent compost added to it along with a starter fertilizer high in phosphorus. Palms should not be planted with their rootball surrounded by pure sand as is sometimes done here in Las Vegas.

Palms are high water users even though they tolerate high temperatures and our desert climate. They are more of an oasis plant rather than a true desert plant. Different types of palms require different amounts of water. The larger the palm, the more water it will require.

Some of the highest water users will be date palms with their huge canopy spreads. The amount of water will vary but most fan palms would be happy receiving about 20 gallons every time they are irrigated.

One of the common problems is irrigating palm trees with small amounts of water frequently. This is often because palms are irrigated with drip irrigation on a line that can only give them a few minutes every day. This can fill the soil with water and exclude any air getting to the roots. This will suffocate the roots and cause them to rot or become diseased or both. So if you are irrigating daily, don't do that anymore.

During the heat of the summer, they can be irrigated two or three times a week, using 20 gallons each time you irrigate, but the soil must freely drain the water away from the tree. In the winter time, you might be dropping your irrigation to 20 gallons every 10 days or perhaps even as far apart as every two weeks.

Sometimes palm trees lack certain types of minerals. This usually appears in the fronds at the center of the canopy. If these are yellowing, then we can usually narrow this to watering too often, poor drainage or a lack of minor elements such as iron.

Next February when you fertilize your palm trees, use a complete fertilizer containing all three numbers. You can also use fertilizer stakes. Make sure it is well-balanced and try to select a fertilizer with the three numbers the same or close to the same value. Add an iron chelate that contains the EDDHA chelate in the ingredients. Let's see if that works, along with irrigating with a large volume of water less often.

Cold damage on palms usually results in the outer fronds turning a bronze color first and then browning later as those parts of the frond that were damaged by extreme cold begin to die. If more than half of the frond has turned brown, remove it. The new fronds at the center of the palm should be healthy green when they emerge in midspring.

If you have a heavy soil that you're planting in, then plant on a mound 2-3 feet high and 6-8 feet across so the water drains away from the roots.

Q: I have a small garden with a big Mexican palm, some canna lilies, various green plants and flowering annuals. Everything does well but I would like to encourage flowering and general health especially during the hot months. I have used Miracle-Gro and I think it does a good job with flower growth but I do find that some flowering plants die off during the summer, particularly marigolds and petunias.

I was told not to use Miracle-Gro as it adds too much sodium to an already salty soil that we have here. Any suggestions for a good fertilizer to use?

A: The idea that Miracle-Gro adds too much sodium to an already salty soil is hogwash. All fertilizers are salts. But to many people salt is sodium chloride.

Sodium chloride is common table salt, not a fertilizer salt. There is virtually no sodium in Miracle-Gro.

Other quality fertilizers you can use include Osmocote and Peters and they do not contain sodium either. What is more important than the manufacturer of the fertilizer when using mineral fertilizers is the fertilizer ratio or the numbers associated with that fertilizer. That is what you need to focus on.

For flowering plants the middle number needs be higher than the first and third numbers. For nonflowering plants, the first number should be higher than the second and third number. When focusing on times of the year when stress is occurring, then the last number should be the highest.

Try to use a fertilizer that has all three numbers present (no zeros) but use fertilizers that have ratios as I suggested to help promote the health and growth that you desire. To some degree, the type of fertilizer that you use, and what I mean by this is the ratio of these numbers, will help to promote specific types of growth.

Bob Morris is a horticulture expert living in Las Vegas. Visit his blog at xtremehorticulture.blogspot.com.