Irregular spots in lawn cause confusion

Q: I need your assistance. The photo I sent depicts the present condition of my backyard. It has patches of dry or dead grass. I don't know what caused the problem. Is there some way to revive the grass without going to the extreme of resodding? And what shall I do to prevent this in the future?

A: Thanks for the picture. The picture helps and it doesn't help. It would have helped if I saw something that gave me a clue. But there is nothing in the picture that is distinctive to me. It would be interesting to know if those dead spots were in any kind of pattern in relation to your irrigation heads.

I did notice that whatever caused the damage appears to be gone. This would tend to eliminate irrigation as a problem unless you changed your irrigation schedule. From your picture, I tend to think it is either insect or disease.

Let me just point out some weaknesses in the design that might contribute to the problem. I tend to discourage homeowners from designing a turfgrass area other than in straight lines. I know this might be somewhat boring but water from sprinkler heads tends to be thrown in straight lines.

Irregular or curving lines tend to cause areas inside the curves to be underwatered or the areas outside the curves and not in the turfgrass to be overwatered.

Another point, those areas of turfgrass closest to rock mulch, sidewalks or patios in full sun tend to use more water than those areas deep inside the turf area. Turf areas close to nonturf areas tend to be warmer and more prone to insect attacks than others.

Insect damage that is fresh tends to cause the grass on the edge of the damaged area to pull up freely from the lawn. If the insect damage is long gone, then it will no longer pull up.

Lawn diseases also can cause patterns like this. Unless a sample is sent to a qualified plant pathologist or we have seen the disease many times before, it is a shot in the dark as to which disease it might be. It is not a pattern I recognize.

Since the problem is gone, there is probably no need to apply an insecticide or fungicide. At this point leave the dead grass alone and do not rake it up or you will open the soil surface to invasion by weeds. Since the cause of the problem is unknown, it would be hard to tell you how to prevent it from happening again.

Around the end of September through mid-October rake up the dead grass, seed the dead areas and mulch the surface with top dressing and fertilizer.

Q: Short story. We had a horse get out of its corral while we were out of the house today, for probably four or five hours. While out, he ate most of the bark -- 60 percent -- off the trunk of one of our pear trees. The tree has quite a bit of fruit on it right now. We are more concerned with saving the tree than this year's crop. Suggestions or ideas on anything we should do would be very much appreciated.

A: Long answer. The good part of this is that your tree, provided it is healthy, will probably survive. I have had fruit trees with that much damage to the trunk survive in the past.

Your horse probably ate all the way down to the wood. This means that the tissue which transports food from the leaves to the roots is gone in that area, as well as the tissue that transports water from the roots to the leaves.

With 40 percent intact on the trunk, the tree may struggle but it should survive. I would recommend that you mulch the ground around the trunk with wood mulch, which you can obtain free from the University of Nevada Cooperative Extension Master Gardener Orchard in North Las Vegas. Saturate the ground around the trunk with water two or three times each week.

Clean the wound created by the horse with a sharp, sterile knife, cleaning the jagged edges of the damaged bark so that they are smooth. You do not need to paint the wound with anything .

Make sure you fertilize the tree next January and each January while it is trying to heal. Enjoy the fruit, but next year thin the fruit out when it is the size of a silver dollar so there is only one fruit per cluster.

Q: I am interested in planting various fruits in my backyard. I am curious about growing blueberries in our region. Do you know how they do here? Would you have any recommendations? I did not realize the varieties of blueberry plants that are out there. In my search I also came across pink lemonade blueberries. I am definitely interested, but I do not want to put forth the effort if they will not be productive.

A: This is the case where your gardening skills are going to be challenged. They are definitely not suited to our climate and definitely not suited to our soils. So let's give it a try.

This means we have to modify the climate and soils they are in as much as possible. Pick a microclimate in your landscape that will be as cool as possible yet still provide six to eight hours of sunlight every day. This would most likely be an east or north side of a landscape that avoids late afternoon direct sunlight. Find a location or create a location that is protected from prevailing strong winds.

Next, modify the soil. Blend anywhere from half to 2/3 of the existing soil with a good quality compost. To this mix, add sulfur that is as finely ground as you can find or in a liquid form. Aluminum sulfate can help lower the alkalinity. It is not used much any more and may be hard to find.

Water the soil thoroughly and let it drain several times before planting. Use only Southern high bush blueberries and space them according to the directions. Stake the plants securely in the soil the first season of growth.

You will need pollenizers so make sure you get the correct blueberries together for good fruit set. Drip irrigation can be used or you can flood the area with water from bubblers. Cover the planting area with 3-4 inches of wood mulch, keeping the mulch about 6 inches away from the stems .

Grow them for one season and see how they do. If you see signs of leaf scorching on the edges you might want to put 30 percent shade cloth over the top of them . Every year you should be adding compost and acidifying the soil with finely ground sulfur or aluminum sulfate plus a good fertilizer and a soil-applied iron chelate containing EDDHA. This is done in the spring before you see new growth .

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