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Pineapple guava needs another variety to cross-pollinate

Q: Wondering if you have any recommendations for varieties of pineapple guava that will fruit in the Las Vegas Valley. Thanks for putting that list of fruit trees that grow well in the Las Vegas area.

A: I have never grown pineapple guava for its fruit. There are small amounts of commercial fruit grown, but it is done in a cooler and wetter climate than our Mojave Desert.

Don’t confuse this plant with common guava. Pineapple guava is certainly not a main fruit crop like tropical guava, which is a totally different plant.

This was a common plant recommended for dry landscapes perhaps 25 years ago before desert plants from the Sonoran and Chihuahuan deserts became popular.

Unless things have changed at the local nurseries, I don’t believe they are selling more than one variety. Pineapple guava will not produce a good quantity of fruit unless you have more than one variety for cross-pollination.

Some varieties are self-fertile, but they produce more fruit if there is a pollinator close by. If you can’t find them here, you might try buying out of state or ordering them from an online nursery.

The flower petals are edible as well and can be plucked from the flowers when they are open. As long as you have two different varieties of pineapple guava, removing the petals won’t have much effect on fruit production by the flowers.

Pineapple guava can tolerate desert soils and the desert environment, even temperatures down to 10 F. Avoid planting in south or west exposures in intense sunlight and heat. They grow best with a break from the afternoon sun and heat such as the east side of a wall or home. Amend the soil with compost at the time of planting, and cover the soil around them with wood chips.

Remember you must have two different varieties close by for producing fruit. Two varieties to look at closely are Coolidge and Trask; Nazemetz is reported to produce good fruit in the Phoenix area.

Q: Nutrients and fertilizers needed by plants are confusing to me. We have people selling “rock dust” to handle some of these nutrients when they are missing from the soil. How do you know which nutrients are important to plants and how much to apply?

A: There are only 16 or 17 essential nutrients absolutely required by plants. Some of them are needed in large amounts and some in very small amounts. These 16 or 17 essential nutrients have been placed into two categories: major nutrients (needed by plants in large amounts) and minor nutrients (needed by plants in smaller amounts).

Fertilizers used by many farmers beginning mostly after World War II, sometimes called chemical fertilizers, contain only three or four of the major nutrients needed by plants. The application of chemical fertilizers contributed to the green revolution in the late 1950s through the ’60s. These nutrients included nitrogen, phosphorus, potassium and sulfur. When used correctly, these fertilizers produced miraculous increases in food production.

Common practices before adding fertilizers included testing the soil for nutrients (soil tests) and testing the plant for nutrients (tissue analysis). These tests determine which fertilizers to apply and how much of each is needed. Soil tests and tissue analysis were common, cost-effective practices for large-scale producers but costly for the home gardener.

For small-scale producers and home gardeners, scientific knowledge, gardening experience and observation are used to determine which fertilizer to apply and how much. For instance, nitrogen causes growth of leaves and stems and a dark green color. When this type of growth is slow or needed, nitrogen might be added.

Phosphorus is responsible for rooting, improved flowering and fruiting. When these results are needed, phosphorus might be added.

When other nutrients are seen to be lacking because of how the plant is growing, these are added to the soil or sprayed on leaves to correct these problems. This is not a cost-effective approach for large-scale farmers, however.

Applying the correct amount of compost and mixing it into a soil can add most of the required nutrients in their proper amounts with the exception possibly of nitrogen. Nitrogen might be added to some plants to increase growth and improve its production.

“Rock dust” became a popular addition to soils primarily because of marketing and some positive results seen in soils that have been depleted of some important nutrients. When I tested three different “rock dusts” on vegetable production in the Las Vegas Valley, I saw no positive benefits from its application if compost was used to prepare the soil ahead of planting.

Q: We have had our lawn nearly 20 years without any problems until this year. It is developing brown spots in the lawn that we think might be grubs. We applied a grub killer we bought from a local nursery, and the brown patches are continuing to grow. But now we think maybe the problem is not due to grubs.

A: Make sure this is not an irrigation problem. Start your irrigation system and watch the sprinklers. They should pop up out of the ground perfectly straight and not tilted in any direction.

Water should spray evenly from the nozzle in all directions. After you run a normal irrigation cycle, use a long screwdriver to judge whether the soil is wet deep enough in the brown areas.

When tall fescue gets damaged by grubs, it doesn’t lift like a carpet. Pull on green grass at several places on the edge of damaged areas next to the healthy lawn. If green grass pulls up easily from these spots, then treat for grubs.

If irrigation and grubs are not the problem, then it is likely a disease problem by default. Disease problems run their course and are over when the weather changes.

If this problem repeats every year, consider applying a fungicide as soon as you see a problem beginning to develop. Fungicides prevent diseases from spreading and must be repeated according to the label.

Consider aerating the lawn if it hasn’t been done for a while. Aeration helps open the soil for better water movement to the roots. It helps prevent disease problems. Aerate anytime, but it’s best done in the spring months before it gets hot.

Remove dead grass from the lawn surface if the lawn feels spongy when walking on it. Use a power rake to remove this dead grass in mid-fall or very early spring. This timing gives the lawn a chance to recover and grow a little bit before winter or hot weather.

Some lawn diseases are carried on mower blades to your lawn from other lawns. Consider that possibility if you have a lawn maintenance company.

Apply a good quality lawn fertilizer or a thin layer of compost to the lawn during the spring or fall months.

Q: I was going to plant some cypress trees a month ago but was called away on a family matter. Is it too late to plant cypress trees and a few fruit trees this time of year or should I hold off until next year?

A: Now is not the best time to plant. It should be done in early spring or even better, mid-fall when temperatures are beginning to cool off.

It should be OK to plant now, but make sure to dig the hole and amend the soil going into it before planting. Water the hole thoroughly and transfer the plant into the hole as quickly as possible to minimize transplant shock. As you are adding amended soil back into the hole, make sure everything in the hole is wet.

Put a basin around the plant and fill it for three consecutive days before turning it over to the irrigation system.

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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