Trees rely on lawns as source of water

Q: I had a purple plum tree for 10 years; then I switched from grass to desert landscaping and the tree lost about half of its leaves. I am assuming that for some reason the tree is dying. When would be the best time to remove the tree and plant a new one?

A: This sometimes happens to existing trees when we switch from grass to desert landscaping. The deep-rooted trees were getting water from the lawn and then that water was taken away when the yard was converted to desert landscaping. They could not survive on the sparse watering most desert landscapes receive.

The hardest hit are usually the bigger trees that require lots more water and are firmly attached to their source of water. The absolutely best time to replant is from about Sept. 15 to mid-October, if you can find a selection of plants that you like.

My desert landscape design series of evening classes through the cooperative extension is being offered starting in mid-September. It will teach you how to design a desert landscape that will avoid this problem and others as well. Call 257-5555 and you can sign up for it. It usually fills up fast. There is a fee for the class.

Q: A friend of mine has a nice turf of Asian grass. That’s the name he gave me and it grows slow but doesn’t take much water. This Asian grass has nice thin blades and he said it gets a little brownish in winter. It didn’t look like the zoysiagrass I saw at the Springs Preserve. Do you know if Asian or Chinese grass is the same as zoysiagrass? Or should I stick with tall fescue?

A: It is probably zoysiagrass. There are three types of zoysiagrass; Japanese, Korean and Manila. The Korean grass is more of an ornamental groundcover rather than a lawn grass.

That leaves two. Of the two, usually Japanese lawn grass is the more common. Of that type, El Toro, released by the University of California, is probably one of the best selections. It is a bit faster growing than some of the other Japanese lawn grasses, which can be an advantage since Japanese lawn grass is notoriously slow to fill in when planted or damaged.

Zoysia will turn brown in the winter but the brown is a more attractive golden brown rather than straw brown, if you like browns. It is slow to fill in when planted so you should plant it rather close together when planting by plugs. This must be planted during early summer. It is late to start zoysiagrass now.

Keep invasive weeds under control because Bermudagrass will try to get established in open areas that are being watered. Zoysia’s water use is about the same as Bermudagrass.

Other possibilities to look at include some of the newer Seashore paspalums and buffalograss; both are good summer grass alternatives to tall fescue. All three will brown during cold weather since they are warm-season grasses.

Tall fescue is a cool-season grass so it does best during the cooler times of the year. It struggles through our hot summers but performs better during the heat than most cool-season grasses.

Q: I am attaching two photos of my apricot tree. It has several branches with only a few leaves and the leaves are turning brown on the edges. It seems to be happening to a new pluot tree that is planted about eight feet from the apricot tree.

A: This is leaf scorch. Leaf scorch results when not enough water gets to those leaves. This means something is preventing water from passing from the trunk to the leaves. The rest of the tree appears nice and dark green and healthy. That is important to note as well.

From the pictures, it is also important to note that only one branch or so is affected and not the whole tree. This means the problem of getting water to that branch is localized at the base of that branch. This eliminates the roots and probably the trunk as well as problem areas.

If you focus on this branch and look for damage, you will probably see it on the upper sides of the limbs from borers or some other type of physical damage. You may even see some sap oozing at this time of year. You can remove this branch any time of the year at its source.

Q: I planted four windmill palms, about 4 feet tall, six months ago. I did put in some soil softener. The drip irrigators are the “flowering type” and I water 30 minutes in the morning and 30 minutes at night. Why are the fronds turning brown during this heat? Do they need even more water? I was told by my gardener that palms do not need excessive water.

A: Windmill palms look a little rugged in our climate. It is not the best climate for them but they do survive. The gardener is right, they don’t need excessive water but they do need adequate water.

All palms require a fair amount of water to do well and they are fairly high in their water use. I do not know how much water 30 minutes is but I would be putting 10-15 gallons or so down every time I watered them. This time of year I would be watering them about three times a week.

Usually scorched leaves mean not enough water, they are not watered frequently enough or both.

They also will do much better if they are growing with about 4 inches of organic mulch on the soil surface rather than rock.

Hopefully you amended the soil with compost or some sort of organic soil amendment besides a soil softener. I do not know what that is, but you might have been sold gypsum as a soil softener, which it is not. The only thing gypsum is good for is to help remove sodium salts from soils laden with sodium. Gypsum is mined here and our soils have plenty of gypsum in them.

You are better off spending your money on organic soil amendments than putting minerals back in the soil.

Bob Morris is an associate professor with the University of Nevada Cooperative Extension. Direct gardening questions to the master gardener hot line at 257-5555 or contact Morris by e-mail at morrisr@unce.unr.edu.