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Wednesday, November 18, 2015

August is Early for Chinese Pistache Fall Color in Las Vegas

Q. My Chinese Pistache was planted in my xeriscape front yard almost 4 years ago. Overall, I’d say it’s doing fine.  One thing puzzling is that the leaves started changing to “fall colors” around the beginning of August.  I don’t remember when it changed colors last or previous years but I think that’s a bit soon.  Again, the tree looks healthy to me but I thought I’d check with you to see if I should be concerned.

A. I agree, August is early in our climate unless there had been some unusually cold weather. Early fall color can be a sign of plant stress and this would be followed by unusually early leaf drop. The usual reason for this type of stress is either a lack of water or possibly watering too often.
Pistache with fall color.
            When watering, give the plant a lot of water all at once so the water drains to a depth of 2 feet, wetting all the roots. This will require that there are enough drip emitters and they deliver enough water if you are using drip.
            Chinese Pistache trees can get large, 40 feet, and the larger they get the more water they will need. Increase the amount of water they receive by adding more emitters every few years. It also helps if this tree has other plants growing around it that are receiving water.
            Do not water this tree daily. That is a big no-no. Watering deep, twice a week, would be plenty.
            Chinese Pistache will survive lawns but the soil under lawns is usually much better than the soil under rock mulch. When they are growing in lawns, this soil can be much more forgiving than the soil under a rock mulch that is getting watered too often.

            Chinese Pistache typically does not have a lot of insect or disease problems in our area so I would tend to think that this would not be the case unless of course you are watering frequently. This will cause big problems for this tree in the future.

Lawn Problems Basically Boil down to Three Types

Q. See if you can figure out what's happening to our lawn. It is dying. I'm very bad with technology so I'll have to send each picture in separate emails.

A. First of all, you did a very good job with the pictures. They all came through just fine.
Dying lawn from unidentified causes.
It is very difficult to determine a problem with the lawn from pictures. Lawn problems basically boil down to three types; disease, irrigation or insect problems. Sometimes it can be a combination of these.
            The pictures make me lean towards a disease problem. The first picture you sent had a combination of two grasses in it; tall fescue and there was a patch of what I think was ryegrass in the center of the picture. In that picture, the problem only affected the tall fescue and not the ryegrass.
The lawn has a color difference that you can see which is actually due to a difference in "texture" more than color. Different grasses have different "textures" due to the reflection of light on the leaf surface. This textural difference is a good indicator that more than one type of grass is present in "patches" and not mixed together.
            Lawns dying because of irrigation usually die in a specific pattern related to the irrigation sprinkler heads. Sometimes this pattern can be in between irrigation sprinkler heads and sometimes the pattern can be close to irrigation sprinkler heads. It depends on a number of factors including the nozzles that are used, operating pressure of the system and the design of the system.
            Homeowners that design their own irrigation system usually tell me it's not due to design because they "did it themselves". Good irrigation design is not something that most people can do. It is much more complicated than people realize.
Not the lawn in question. Grass suffering from drought will grass near the damaged area with a darker appearance than the rest of the lawn. This is because blades of grass either "roll" or "fold" in response to a lack of water and cause this darker appearance during times of drought.
            There are many landscape contractors who are skilled at irrigation design or they purchase the materials they need from companies that provide for them a professional irrigation design. Fly-by-nighters will not be skilled in this area.
            Poor irrigation coverage or management will contribute to disease problems and lawns. It is imperative that a good looking lawn has an irrigation system that is designed and installed by professionals.
            Poor irrigation management will contribute to disease problems. Never irrigate a lawn if there is more than three hours of darkness after the irrigation has been completed. A wet lawn sitting in darkness for more than four or five hours when temperatures are above 80° F has a very high probability of becoming diseased. In other words, "Never put a lawn to bed wet."
            I was not in town in September and I understand there was a long period of wet weather and warm temperatures. When I heard this, I was thinking this was an ideal condition for disease development in lawns.
            Disease problems may develop in a pattern or they may not. It really depends on the disease and to a lesser degree the management decisions applied to the lawn. Judging from the pictures you sent and what I have seen historically here I lean more towards a disease problem.
Diseases in lawns frequently develop some type of "pattern". Not always but it can be a good indicator that a disease is at work.
            What to do? Diseases will run their course until there is a change in the weather or management practices. If this disease problem began during September rains then the lowering of temperatures and low humidity stopped the disease from spreading further. It will probably do little good to apply any kind of fungicide now.
            We are getting to the tail end of the lawn planting season. I would make a decision to either replant the lawn from seed or sod but you should get it done by the middle of November at the latest.
            If you decide to re-plant from seed then mow the areas that are dead as short as possible and rake or power rake these areas until you see bare soil. Seed these areas with a good quality lawn grass. If your lawn is predominantly tall fescue, then select a good tall fescue blend and don't use a cheap one. If you are going to lay sod in these dead areas, rent a sod cutter and lay some new sod in these spots.

Backyard Wildlife in Las Vegas

Here are some pictures sent to me by readers of some wildlife they saw in their backyards recently. Remember the fires that occurred in the Mount Charleston area a while back. Water is a great way to attract all types of wildlife into your yard.
Bird at birdbath identified as Cooper's Hawk
One of the readers reported to me that she saw this Cooper's Hawk take out two pigeons.

Wikipedia on Cooper's Hawk
Wikipedia on great horned owl
Bird at birdbath identified as horned owl

Oleander Toxicity Probably Not A Problem for Vegetables When Composted

Q. I read you said recently that oleanders can be composted. Just for clarification, can they be composted for vegetable gardens since they are toxic?

A. Yes! They can be used for mulching and composting! Mulching is when the plant is chopped up into small pieces and laid on the soil surface. Composting is the controlled rotting of the plant so that it can be mixed in the soil as an amendment and fertilizer.
            There is contradictory information circulating on the Internet about the safety of oleander but the study below strongly suggests that there is no problem with it when it is composted and used for growing vegetables. They do warn that it is not safe to eat the compost (why someone or an animal would do that I don't know). It is also not a problem to compost eucalyptus as well.

            The smoke when burning oleander is a problem if inhaled. Although about 60% of our landscape plants are poisonous to some degree, oleander is one of the most toxic along with Datura spp. (a.k.a. Jimson Weed, Angel’s Trumpet, Thorn Apple), Nightshade, Castor Bean (Rosary Bead), Rhubarb, Moonseed, Lantana, Yew and Wisteria.

Clean up Debris to Reduce Skeletonizer Populations

Q. Although I was able to control the grape leaf skeletonizer all summer, I came back from a three week trip with 99% of the leaves stripped and dried up.  The grapes were picked in August and September. Should I still treat the vines with BT or just forget it since it is October and the leaves
would have soon turned brown anyway?
Skeletonizer feeding on the bottom side of grape leaves.

A. I would just let it go at this point. The only thing I worry about a little bit is regrowth (new leaves produced) because the temperatures are still warm. Regrowth will drain stored food reserves from inside the plant.
            These reserves are used for next year’s production but there should be plenty of “food” left even if it regrows this fall. I would not worry about it if that happens.

            Make sure you cleanup the leaves at the base of the plants. This is where the pupal stage (cocoon) will overwinter and if you do not cleanup this debris the attack on the plants next year will be earlier and more intense. The adults are winged moths so they will move from neighbor’s vines to neighbor’s vines. 

Curled Leaves on Pomegranate

Q. Our pomegranate tree has been planted for 5 years. We've had some fruit the past 2 years.  Lots more this year. I just spotted one already split with critters on it. The leaves look shriveled. Gave it fruit tree fertilizer and an extra watering. Any other suggestions would really be appreciated.

A. I looked at the pictures you sent to me and your pomegranate does not seem to be very full. The reasons they tree may not have filled out is because of the shade or not enough light during the day, not getting enough water or not fertilizing at the beginning of the growing year.
            Don’t worry about the curled leaves. This can be fairly common on pomegranate.
            They like to be deep watered just like any other landscape tree or shrub or fruit tree and watered about as often as well. If you want good production, don't treat them like a cactus. So in short, fertilize the tree in late January or February and start weekly irrigations the first week of
            I would construct the basin around the tree about 3 feet in diameter and 3 to 4 inches deep and fill the basin each time you irrigate. If you are to use drip irrigation, and they will perform good on drip irrigation if they're getting enough water, then make sure you have about four emitters and you run them long enough to deliver the water they need.
            The critters you see are leaf footed plant bugs and normally soap and water sprays would be enough to knock them back but you'll have to apply it weekly to the undersides of the leaves and all over the foliage.

            Pyrethrins sprays will also work on them. And if you are hard-core, the insecticide is Sevin will kill him but don't spray when the plant is in flower and spray very early in the morning or at dusk when bees are not present. I hope this helps.