November 2015 – Page 2 – Xtremehorticulture

When Removing a Lawn, Large Trees Frequently Die

3 Comments / Cash for grass, converting landscape to desert, converting landscape to rock, SNWA rebate / xtremehorticulture

Q. We’re seriously considering getting rid of our turf and taking advantage of the SNWA Rebate Program (“Grass for Cash” Program). However, not at the expense of our beautiful fruitless mulberry. What steps do we take to maintain the health and vitality of the tree? Mulberry that might be threatened in a “cash for grass” rebate program. Most landscapers will not provide enough water in the right locations for a tree of this size to survive. A. Great looking tree and I applaud your efforts to keep it although I am sure those with severe allergy problems would like to see it gone. As you have discovered, the water needed to support a tree like that is nearly equal to the amount of water applied to the lawn underneath it. The best advice I have is to maintain the grass directly under the canopy of the tree. If you decide to remove all the grass, then you will need to add a way to deliver enough water directly underneath the canopy. A method that some people are using is to lay a coil of in-line drip emitters around the tree in a spiral, spacing the tubing about 12 to 18 inches apart. Use tubing with emitters spaced about 12 inches apart along its length. The less distance between emitters, the less time will be needed for watering. I am guessing this method will require about one hour to deliver enough water for the tree in a single irrigation. Other plants can be planted in this area that will take advantage of the wetted area. Another method, and the one I like the most, is to flood irrigate about half the area under the canopy with two bubblers in a constructed basin that is at least one third the diameter of the canopy. The basin must be level so that the water does not accumulate on one side of the basin. It will take about 10 to 15 minutes to fill the basin with enough water to supply the tree. Pine tree with a bubbler and basin used to for irrigation. The bubbler releases water quickly and fills the basin. It is important that the bottom of the basin is flat. The most common option is to use drip emitters under the tree. This seldom works when keeping large, mature trees like yours healthy. You would need a very large number of drip emitters to deliver enough water. Very few retrofitted desert landscapes use enough to keep the tree from dying back. This tree previously was growing in lawn. This area was converted to a rock landscape, the grass removed, to conserve water. This tree was not provided with enough water after this conversion so it began to die. Consider covering the soil under the tree with wood chip mulch rather than rock mulch to maintain good “soil health” under the tree. Good soil health was promoted in the past by maintaining your lawn. With the lawn gone and the soil covered with rock mulch, soil health will be severely impacted which will negatively impact the health of the tree in a period of 3 to 5 years.

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What Edibles Can I Grow in Shady Spots Along a Walkway?

1 Comment / growing edibles in shade, growing herbs in this shade, Growing vegetables in shade / xtremehorticulture

Q. I am creating garden beds along a walkway on the west side along a north facing wall. It is shady there most of the day. What edible plants can I grow there this time of year? Here is the walkway in question A. The area next to the sidewalk is a long, a north facing wall so it does not get much sun. Because it receives less sun, the production of food will be lower. To come close to maximum production of food of good quality it needs at least eight hours of bright light. Very bright indirect sunlight reflected from light colored walls will help production in this area a lot. Less than six hours of bright light will severely impact the quantity and quality of vegetables produced from flowers such as tomatoes, peppers, squash, etc. There will be fewer flowers and thus fewer fruits from these flowers. You would focus on greens, many kinds of herbs, possibly onion and garlic. Keep in mind that leaf and stem growth is also affected by light. Leaves that grow under lower light levels tend to be larger, thinner and tend to tear or rip more in wind and when harvested. They also tend to be less bitter. On the flipside, vegetables produced under the high light intensities of the desert tend to be more compact, thicker, more bitter and frequently tougher in texture. Full sunlight tends to produce more nutrient-dense leaves, stems and fruits but may reduce its eating quality or texture. This time of year focus on the cool season stuff like mustards, kale, lettuce, spinach, and beets, cauliflower, broccoli, rapini, carrots, escarole, mizuno, and the like. Some herbs include parsley, sage, rosemary, thyme, chives, lavender and cilantro.

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What Cause Whitish Spots on the Leaves of Star Jasmine?

1 Comment / spots on leaves, Star Jasmine / xtremehorticulture

Q. My star jasmine leaves are covered with a whitish plaque. The leaves are turning yellow and falling off. I have noticed the green leaves are only at the end of a branch and bare to the main stem. The plant is approximately two years old and facing east on the side of a patio. What can be done? Star jasmine with whitish spots on the leaves. A. I took a look at the picture and I saw the white spots on the leaves but I could not determine what it was from the picture and your description. I can only tell you about some general problems with star jasmine. First of all, star jasmine will do very poorly in desert soils if the soil was not amended with compost or a good soil amendment at the time of planting. Their roots will not tolerate soils that drain water poorly as well. They do like soils covered with organic mulch. They tend to get root rot diseases in these types of soils and they will develop yellow leaves along with leaf drop just like you are describing. However, the white spots are a bit of a mystery. Star jasmine has milky sap in it stems and if the stems are cut they will drip a milky sap on the leaves so watch for that. If they were pruned recently they might have the milky sap dripping on leaves. This would probably be unrelated to the yellow leaves and leaf drop you are mentioning. Bottom line, don’t plant star jasmine in our desert soils without amending the soil a lot with compost or other suitable soil amendment. Consider organic mulches on the soil surface.

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Growing Redwoods in Las Vegas Poses Long-Term Problems

Leave a Comment / giant Sequoia, growing them in the desert, Redwood trees / xtremehorticulture

Q. We are growing some redwood trees on our property in containers. Some of them on the south side of the home that have been in containers for several years have branches dying at the bottom. Younger ones in containers on the north side seem to be doing well. A. Congratulations that you are trying to grow something different than what is found in the local nurseries and garden centers. I encourage people to push the limits of their environment by growing a variety of different plants. But remember, whenever growing plants, like redwoods, that don’t belong here you will need to invest more time, energy and money to get them to grow here. Redwood tree in its natural habitat with man posed in front of it for perspective. From Wikipedia https://en.wikipedia.org/wiki/Old-growth_forest#/media/File:Redwood_M_D_Vaden.jpg https://en.wikipedia.org/wiki/Old-growth_forest#/media/File:Redwood_M_D_Vaden.jpg Soils in containers become “exhausted” in a couple of years and must be renewed. I try to relate it to a fish aquarium. Periodically about one third of the water in an aquarium should be removed and replaced with fresh water. In a similar way, about one third of the soil in a container should be removed and replaced with fresh soil every 1 to 2 years. Adding new soil to a container is like changing the water in an aquarium. Both rely on replacement to keep the arguments healthy.Picture is from Wikipedia https://en.wikipedia.org/wiki/Freshwater_aquarium#/media/File:Aquarium_60cm.JPG The second problem is the mature size of this plant. If you want this plant to grow for any length of time at all it should be grown in the ground, not in a container. These trees will get much too large to maintain in containers. The third problem is exposure. The south side of the home is much hotter than the north side. Plants that do not enjoy our desert environment perform much better on the north side, in the shade, than on the south side exposed to intense sunlight and heat. Even if the trees are protected from exposure by a house or other building, when they grow above this protection you will begin to see damage to the exposed parts of the tree in our climate and soils. A fourth problem is our tap water. About three fourths of it comes from the Colorado River and contains a high amount of salts. Redwoods do not like salts in the soil or the water and the salts will cause problems for these trees in containers. Your trees are probably “root bound” with spiraling roots that will never become established even in the best landscape soils. If you want to keep them, put them in the ground on the north side using improved soil and stake them for support. Enjoy them for as long as you can but realize that eventually they will succumb to our desert.

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My Pomegranate Tree Produced No Fruit

Leave a Comment / fruit production, pomegranate / xtremehorticulture

Q. I have had a pomegranate tree for five years. The first three years it had fruit, even the first year I planted it. Last year and this year it has had no fruit. Can you tell me what to do for it? I prune and fertilize it the same way every year. A. Pomegranates flower on the growth produced the same year the fruit is produced. In other words, unlike many other fruit trees, it flowers and produces fruit on new growth. Pomegranate flowers It is very important to prune pomegranate before it begins to flower and avoid pruning during its growth. Pomegranate flowers and produces the best fruit on new growth coming from older wood. Some varieties of pomegranates, like yours, produce fruit when the tree is very young. Other pomegranates produce fruit after they get a bit older. As an experiment I would try not pruning at all this coming year and see what happens. When pruning pomegranate leave four or five main stems at the base and remove all other sucker growth. The best pomegranates will be produced from this older wood. Another possibility could be the presence of some pretty nasty bugs such as the leaf footed plant bugs. You say your tree had no fruit but you did not say whether it produced flowers or not. If it produced flowers but no fruit than it is very likely the leaf footed plant bug was hard at work on your tree. If you have broadleaf evergreen trees such as bottlebrush (not pines), spray these trees during the winter months for leaf footed plant bug. These insects hide and feed during the winter months on trees that are evergreen or keep their leaves during the winter. Bottlebrush in the winter with its very different looking seed capsules resulting from the flowers. These insects will be in full force when your pomegranate begins to produce fruit. Their feeding can cause fruit to drop from the tree at a very early age. Safer is insecticidal soap is one example of a commercially made soap product safe to apply on plants. Soap and water sprays will control them if it is sprayed directly on these critters. Soap and water will not work if the tree is sprayed and you hope they come in contact with it. Chemical sprays that appear to work well against this insect include pyrethrin sprays and those that contain the conventional insecticide Sevin.

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August is Early for Chinese Pistache Fall Color in Las Vegas

Leave a Comment / Uncategorized / xtremehorticulture

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.

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Lawn Problems Basically Boil down to Three Types

Leave a Comment / dead grass, dead lawn, lawn disease, turfgrass problem / xtremehorticulture

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.

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Backyard Wildlife in Las Vegas

1 Comment / Uncategorized / xtremehorticulture

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

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Oleander Toxicity Probably Not A Problem for Vegetables When Composted

Leave a Comment / Uncategorized / xtremehorticulture

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. Composting Oleander Recommendations 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.

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Clean up Debris to Reduce Skeletonizer Populations

Leave a Comment / Uncategorized / xtremehorticulture

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.

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