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Monday, October 10, 2011

Autumn Blaze Maple Not a Good Choice for Las Vegas

Q. I enclosed pictures of a little sapling from North Carolina I bought on line March 2010 several months ago all the leaves turned brown on their edges only. Now the complete tree is burned to a crisp all over. It’s not too much water/or not enough. We live in Sun City Summerlin.

A. Thank you for knowing and remembering what plant bought and its name.  This helps me a lot in tracking and learning about this plant before I responded.  Autumn Blaze maple was hybridized by an Illinois nursery in the 1980s.  In the Midwest or other suitable climates such as the east coast or Pacific Northwest, it will grow to a height of 60 feet and 40 feet wide.  It is called Autumn Blaze caused of its splendid red and orange fall colors that can be seen in those parts of the country and I’m sure this is why you selected it. 

This is a case where you have chosen a tree which is just not suitable for our soils or our climate.  This particular maple tree is a hybrid between silver maple and red maple, both of which struggle in our alkaline, saline soils and extremely high temperatures.  A tree with these two parents in its lineage doesn’t have much of a fighting chance in our desert environment. 

The pictures you sent me show that it is already struggling here which is evidenced by its scorching leaves.  You might be able to give it a fighting chance for a couple of years by heavily amending the soil at planting time with compost and leaching the soil water making sure that the soil drains easily. 

You would secondly mulch around the tree with wood mulch, not bark mulch and of course no rock mulch. With adequate amounts of water and organic amendments you might get a tree that is healthy enough to withstand our environment for a few years. 
Readers Autumn Blaze mape tree planted in Las Vegas

Both parents of this tree are highly susceptible to iron chlorosis and would need treatment for this problem even if you could get it healthy.  I’m sorry to give you the bad news but this is a tree which should not be grown here.

Lawn Brown Patches May Be Summer Patch aka Fusarium

Pictures from reader concerning the brown patches
in her lawn
Q. I have some brown patches in the grass in my yard.  The sprinklers are working fine and the recent rains haven't made any difference.  This area was nice and green until about three weeks ago.  I'm hoping you may have some idea what is causing this and what I might do to resolve the problem.  The rest of the yard is fine.

A. Your lawn has, from the pictures you sent, what appears to be summer patch disease. This disease used to be called Fusarium patch in the old days. Some management techniques that you can try include mowing the lawn a bit shorter during the heat of the summer. 

            If you fertilize your lawn during the summer make sure you use half the amount recommended on the bag or less. Fertilize in the early morning hours only and make sure it is watered in immediately after the application. Foliar applications would be even better.

            Avoid watering the lawn anytime between late afternoon and early evening and about 2:00 AM. You can water any time after 2:00 AM but try to get it done before sunrise.

            Otherwise you will need to apply fungicides to your lawn that have been approved for controlling summer patch or Fusarium diseases. You can find this out by reading the label. Fungicides are best in preventing diseases from spreading not curing them after the disease has ravaged the lawn. Mark your calendar for next year and apply a fungicide anytime you see summer monsoons predicted.

Grape Leafhopper Damage or Fleabeetle Damage

Picture of grape demon from reader
Q. These critters have devastated one of my grape vines. Here is a picture. Thousands of little sucking holes ruin the leaves and thus the vine. They are about 1/4th inch long and may also fly. What are they and how can I defend against them for next year?

Grape leafhopper damage see the yellow speckling
from feeding damage and black poop spots
A. The picture was a bit blurry but appears to be grape leafhopper. However the description of the damage sounds like grape flea beetle. If leafhoppers the insects are small, maybe ¼ inch long. In their mature stage they can jump short distances. There can literally be thousands of them on a grapevine many of them jumping when you walk by the vine landing on your face and clothes. Very irritating.

Grape fleabeetle damage leaves holes in the leaves
            They can be curtailed by applying an organic biological control of Spinosad in early May and again mid-May when the nymphs or immature forms are present. It will control the nymphs but does not do much to the adults. If you get it applied early enough this will reduce the population when the adults mature. Make sure you spray the underside of the leaves as well as the tops.

            If these are grape flea beetles then they should be gone in about two weeks and a pesticide is usually not necessary as the damage is not long term.

Junipers Not Ideal Choice for Desert Landscapes and May Have Some Problems

Pictures of carpet juniper with needle drop from reader
Q. Please advise and diagnose how to resolve a problem I have with my juniper bushes. I hope my pictures help.

A. From your pictures the juniper appears to be one of the very low-growing carpet junipers, not sure which one but perhaps green carpet juniper. These carpet junipers can be confusing and can be from several species. Which juniper is important as some junipers are more heat tolerant than others.

            J. horizontalis has among its cultivars probably one of the better heat tolerant rug-type junipers.  Regardless, junipers will do better in this climate if not put into extremely hot environments and surrounded by rock. They usually can handle some of the poorer soils that you can develop in rock landscapes at least for a few years if not more.

            Probably the biggest problems will include not enough water or not watering frequently enough, salt problems and spider mite infestations. Watering too frequently (daily) can cause root rot and death of the plant.

            Make sure there is at least one day between deep waterings during the heat of the summer. One plant will probably require around five to ten gallons per watering. You can determine this by checking your drip emitters for the gallonage per hour and adjusting this amount through the number of emitters per plants multiplied by the fraction of the hour that it remains on during one irrigation.

            Spider mites are a problem on junipers. They are not insects but are more closely related to spiders. They are very small and not seen easily with the naked eye. Their feeding results in speckling or yellow spots on needles. Some needles may turn brown and drop off.
Two-spotted spider mite

            With heavy infestations, fine webbing may be seen on the plant. If not controlled, spider mites can kill junipers. Most spider mites increase in numbers during hot, dry weather.

            Naturally occurring enemies of mites will usually suppress mite populations. Since insecticide use kills these enemies as well as mites, insecticides should be avoided unless absolutely necessary. Miticides, labeled specifically for mite control, are less harmful to these natural enemies. Mites can be removed with a strong spray of soap and water, if applied on a regular basis.

Webbing due to spider mites
            To determine how many mites are present hold a white sheet of paper under a branch and slap it on the paper. The mites knocked off on to the paper will be seen crawling around as tiny spots the size of this period. If dozens of mites are seen crawling on the paper it is time to do something.

            Pesticides labeled for homeowner use against spider mites include insecticidal soaps like Safer Insecticidal Soap or Ortho’s Systemic Insect Killer. As with any pesticide, read and follow all label directions and precautions before using.

Woody Suckers in Lawn Can Be Eliminated

Picture of weed from reader which I could not identify
Q.  Can you identify and tell us how to kill forever a noxious weed that is single stem, upright, red thorns every few inches. I hope the picture I sent is good enough. Roots are woody and thick to 1 inch in diameter.  Roots run across and under my son's entire lawn and fairly deep.  Suckers keep coming up.  I would love to kill it forever without digging up the whole lawn. 

A. I couldn’t tell from the picture. The description doesn’t sound familiar but it sounds like a woody plant that suckers from the roots. I am assuming they are coming from a woody plant close by, a neighbor’s yard perhaps.

            Any lawn weed killer that has dicamba or Banvel in the ingredients will work. This can be applied directly to the lawn without hurting the grass but will damage or kill woody plants and weeds that are not grasses. This will require multiple applications to keep killing new sprouts as they appear.

            You will see more suckers as you use this product and it may seem like it stimulated their growth but it has not. It has caused them to sucker more below ground due to the death of the existing suckers above ground.

            Repeat applications will exhaust the reserve of woody growth under the lawn until they finally stop coming up. But you must stay on top of them with this weed killer for at least one season.

Amaryllis Survives Las Vegas in the Ground

Amaryllis of readers
Q. I was wondering when is the best time to transplant the Amaryllis plants, now or in the spring?  They bloomed beautifully this past summer, but seem to me to be getting a bit pot bound (which I know often promotes blooming in some plants).  I intend to transplant them to larger pots sitting next to them.  I also wonder if regular potting soil is best or if there are other things I should add that would help them and when and how often they need to be fertilized and what type of fertilizer to use.  I top them off with mulch.

A. As far as your Amaryllis is concerned they do quite nicely here if planted on the eastside of your landscape and in some light shade. They do not need to be in containers but can be planted in improved landscape soils.  Good quality compost is best. 

            If they are planted into a desert landscape make sure they are planted in one of the high water use areas so they get enough water often enough. They can last in a landscape five years or more without digging them up.  Cut back on your water to them during November and December and early January.  They need a rest period before blooming again. Fertilize them monthly with a week of fertilizer solution as soon as growth begins. Any rose type fertilizer or fertilizers for flowering plants will work.