Q. I’m curious if there is any other reason other than drought or overwatering that would cause my donut peach growing in a container to wilt within 24 hours? I pruned the dead branches off and touched very little of the live wood. Donut peach wilting A. Donut peach, sometimes called bagel peach, Saturn peach, pan tao peach, and a bunch of other names, are a good choice for our climate and soils. They are a novelty but deliver very sweet fruit great for eating fresh and birds love too! A problem that I have mentioned in the past as well as how to avoid it. Stark Saturn Donut peach             Thanks for the pictures and I will post them here and on my blog. I understand it is still in the container and you will plant it soon.             For leaf wilting to occur, something is stopping the water from reaching the leaves. This could be a soil problem, root damage, stem damage or direct damage to the leaves. Obviously, a lack of water or watering too often so the roots suffocate can cause wilting.             A common problem this time of years is applying fertilizer or strong compost too close to the trunk. This can cause the leaves to wilt because of the high nutrient content (salts) in fertilizers and many rich composts. If applied next to the trunk or against it, it can cause plant wilting followed by death.             Apply fertilizers and compost no closer than 12 inches from the trunk. If the container is smaller than this, then use a very small amount and apply it more often. Stark Saturn Donut peach with bird damage             Check for borer damage on the trunk. I had trees coming from the nursery, both container and bare root, with borers already in the trunk. If your tree had borers in it the same season you bought it, the borer came with the tree when it was bought. No extra charge!             Spray the trunk with water from a spray bottle several times until the stem is soaked. If the borer is active, you will see globs of brown or dark red sap coming from the stem. Sometimes I can squeeze the stem with my first two fingers and I can feel “sponginess” where the borer is feeding just under the bark. Dig it out with a sanitized, sharp knife and let it heal.             It is possible that spray drift from weed killers could do it but I may be grasping for straws with that one.  When using compost as a fertilizer for fruit trees keep the compost away from the tree trunk.

Q. You emphasized it’s better to water longer rather than more often. But what if that’s not possible? Our small condo community has an old irrigation system with everything watered from the same lines. We irrigate for nearly 24 hours. Less than that and small plants really struggle. Is there anything we can do?  This picture says it all. This is an example of the Mini-oasis landscape design pioneered by the late Dr. Warren Jones (University of Arizona). He and Mary Rose Duffield published a book called “Trees for Dry Climates” in the 1980’s that talked about this water saving design technique now renamed hydrozoning. I “borrowed” this picture from Sunset Magazine many years ago. Thanks Sunset! A. Telling you to water longer rather than more often, I am telling you what to strive for, what’s best for the plants, your condo community and your landscape. There is no “quick fix” to use when irrigating that solves this problem without making major changes to the landscape and irrigation system. This is a “birds-eye view” of the same landscape in Tucson. Thanks again, Sunset!             I am very confident your condo community could have an eye appealing landscape that could save water and energy while not using more than about 2 to 3 feet of water applied to your landscape per year. Lawns use between 6 and 8 feet of water per year, 200 to 400% more. This shows an irrigation layout for a minioasis design. The valves are isolated to three different watering zones; high, medium and low. This is how water is conserved while still making life comfortable in our hot desert climate. I am indebted to you, Sunset!             Landscape water use should aim for between 650,000 to 975,000 gallons per acre per year. Some areas of the landscape, where people are active, are more intensively planted and use more water while other areas use less but the average should fall between these numbers.             If you are currently using an amount of water that is close to this and happy with how your landscape looks and performs, then do nothing. You are doing a very good job in managing exterior water use.             But if landscape water usage is considerably higher than this, then consider re-landscaping the common areas. This can be done in stages so the upfront cost is manageable.              Most likely the irrigation strategy used now in your condo community is giving landscape plants many small “sips” of water rather than large gulps. It is not ideal but if it’s working for you, and not cost-effective to make changes, then keep everything the same.             Plant replacements should be planted during the coolest times of the year and not during the heat. Designate someone to water these plants with a hose about every 3 days after they are planted. After new growth has begun, they can be turned over to the irrigation system.             Seldom are there noticeable problems from watering plants with too much water unless the applications are excessive. Excessive watering causes plans to yellow and died during the heat.             However, problems you MIGHT see irrigating daily with tiny sips of water include plant leaves scorching, plants dying back, large trees that blow over in strong winds and excessively high water bills.

Q. My peach tree produces copious amounts of fruit but they have a bitter taste year after year. What can be done to sweeten the fruit? Genetic dwarf or “Miniature” peach. These are NOT called semi-dwarf but are true genetic dwarf. They stay very small and commercial growers thought genetic dwarf trees would revolutionize the peach industry. They didn’t. The fruit quality was not nearly as good as they hoped. They are popular in home landscapes due to their size. A. This is a problem with the variety of peach you selected. Variety names are names like ‘Bonanza’ dwarf peach, ‘Elberta’ peach, ‘FlordaPrince’ peach or ‘MidPride’ peach. There is nothing you can do to the tree or the soil to improve fruit quality. If you are not happy with the quality of the fruit after 3 or 4 seasons, replace the tree. One of the Elberta type peaches. Popular in the desert as well as the humid eastern states.             If yours is a miniature peach, like ‘Bonanza’, a genetic dwarf tree, then this could be the root of the problem. Genetic dwarf or miniature peaches were never accepted by the commercial peach industry because of fruit quality. Donut peaches like this ‘Stark Saturn’ are a novelty peach in both yellow and subacide white flesh and very high sugar content when allowed to ripen on the tree. Performs very well in the desert with high sugar content.             Some years the quality of the fruit produced is better than other years but generally the fruit quality is subpar when compared to varieties of fruit grown on standard-sized trees such as ‘Elberta’ or ‘MidPride’. A favorite peach of mine because of its shocking red flowers in the spring and very good fruit flavor in the desert.             Choose a peach by its varietal name and find out what varieties are good ones for our desert climate. The variety of the peach is extremely important for good fruit quality. Some of these varieties are marketed as “semi-dwarf” because of their grafted rootstock. The quality of the fruit is still good regardless of the rootstock but stick with a reliable varietal name. Another personal favorite, an old timer, Indian Blood peach. A subacid peach with wonderful floral qualities, delicious fruit and shocking red flesh when left on the tree to ripen.             Fruit quality varies with variety and climate where it’s grown. Fruit tree varieties that taste delicious in Georgia may not have the same quality when grown in the Mojave Desert. This is also true vice versa. Another favorite and not because of its flavor but because it is so early. Hard to find a peach producing fruit in May, even before most apricots. But ‘Earlitreat’ variety does. Along with FlordaPrince and FlordaKing. Solid early producers for the desert with good flavor.             In hot climates, the usual problem is a lack of flavor because of low acidity even though the sugar content can be very high. Sugar only tastes sweet. The balance of different acids is what gives a peach flavor. I would replace this tree with a variety that has a history of good flavor in our climate. See my list of fruit trees for the Mojave Desert

Q. I have a hybrid Bermudagrass lawn with weed problems of clover, crabgrass and chickweed.  I sprayed the lawn in spring with a liquid weed killer using garden hose. Weeds loved it. I bought a spreadable product which can’t be applied during temperatures above the 80’s.  Is there anything that I can do before the fall?     Most high end golf courses like this one in the hot Mojave Desert climate uses hybrid bermudagrass as its base and overseeds with perennial ryegrass in the fall if the price of water permits it. Hybrid bermuda has been the grass of choice in hot climates because of its beauty and resilience. A. Hybrid Bermudagrass, if managed correctly, will have very few weeds as a residential lawn if mowed, fertilized and watered correctly. Mowing frequently at the proper height, applying high nitrogen fertilizers every 6 to 8 weeks and watering to keep it “perky” keeps most weeds at bay. Hybrid bermudagrass must be mowed frequently to encourage horizontal growth which is important for keeping weeds at bay. Frequent mowing creates shade on the soil which discourages weed growth. This is a Toro reel-type mower for mowing golf course fairways, greens and tees.             Mowing height depends on the variety of hybrid Bermudagrass. All of them should be mowed below one inch and a few of them grow best when cut at ½ inch or less. Frequent mowing at these heights encourages a thick, horizontal mat of grass that prevents these weeds.             Apply high nitrogen fertilizers every 6 to 8 weeks during its growing season, particularly in the summer months. Reduce the amount of fertilizer applied to the grass to between ½ to 3/4 of the recommended rate on the bag. Fertilizing with high nitrogen fertilizers and mowing frequently work well together to prevent weed growth. Ammonium sulfate is a conventional mineral fertilizer high in nitrogen which promotes leaf, stem growth and dark green color.             Irrigate during the early morning hours before sunup. Make sure to apply enough water to penetrate the soil 12 inches deep. You will be surprised at how many of these weeds will be eliminated through proper mowing, fertilizing and irrigation.             Weed control in Bermudagrass is more effective in the spring and fall when temperatures are cooler. Weeds are more resistant to weed killers when stressed by the heat. Weeds are more susceptible to weed killers during cooler months. Goosegrass looks very similar to crabgrass except for white radiating from the center when it is mowed. Pre-emergent weed killers must be applied about two months later to control goosegrass compared to crabgrass.             Make sure it is crabgrass and not goosegrass. They look very similar. Crabgrass control begins mid to the latter part of January. Goosegrass control begins 2 months later. Pre-emergent weed killers are applied to the lawn to kill seed as it germinates so these weed killers must be applied before the seed germinates or you’ll get no control. Follow label directions. Crabgrass doesn’t have this white center like goosegrass and it appears much earlier in the season. Weed control for crabgrass happens very early in the spring.             To control clover and chickweed use a liquid weed killer containing either MCPP, 2,4-D and dicamba OR MCPA, 2,4-D and triclopyr listed as ingredients on the label. Apply it either in combination with a fertilizer and applied with the drop spreader or liquid applied with a compressed air sprayer. Hoes-end applicators, in my opinion, do not do a very good job.             Do not apply water for 24 hours after an application. Mix a wetting agent with the spray to help it get inside the leaves. Read and follow label directions.

Q. Can I use burlap for shade cloth? Hoophouse shade cloth of about 30% A. Don’t use burlap in place of shade cloth for vegetables as a solid piece. It is fine for creating shade for people or pets but not for plants. Be careful how much heat it traps under it if it is located too close to humans and other animals. Plants are green and need sunlight for photosynthesis. People and pets don’t need as much sunlight. Shade cloth of a different percent shade attached to the end of the hoophouse. Vegetables growing in this area struggled due to a lack of light.             Shade cloth comes in different percentages of shade ranging from about 30% to 100%. Shade cloth for plants ranges from 20 to about 50% shade. Plants that flower and produce fruits like tomatoes, peppers and eggplant grow best under 20 to 40% shade. Shade more than this interferes with flowering and fruiting. Red shade cloth used at a commercial nursery to accelerate growth and increase foliage volume for house plants, non-flowering herbs, and a variety of field and nursery plants.             Plants that only grow leaves and no flowers such as lettuce, spinach, Swiss chard, greens can handle shade up to about 50%. After 50% shade, they grow poorly. Not enough light.             Most burlap I have seen produces much more shade than this and would not be a good choice when growing plants. Aluminet 50% shade cloth used for low tunnel tomato production in the Mojave Desert             You can make 50% shade out of wooden 1×2’s by laying a solid ceiling of 1×2’s above the plants and then removing every other one. Similarly, 30-40% shade can be done the same way but by eliminating 2 and leaving every 3rd 1×2. You could possibly do it with burlap as well but it would have to be in alternating strips to allow light to shine on the plants from between the strips.

Q. I recently purchased some rubber mulch to replace wood chip mulch I have been using in the past. I put it around some of my trees and shrubs. What is your opinion of this kind of mulch? A. There is good and there is bad. The good part is rubber mulch is made from recycled materials, waste that would otherwise be recycled in other products or put in a landfill. Too much of it goes into available landfills already. Recycling includes use in new tire manufacturing, rubberized asphalt, energy production, and burned as a fuel. It is proposed that use of shredded tires poses no health concerns but there are objections because of their heavy metal content and possible source of pollutants. It has been used in children’s playgrounds where it has been a source of many concerns. The problem is basically over the costs associated with recycling. Personally I don’t like it as a mulch for plants, particularly food plants. I would not use it for that. I think there are other ways of recycling it without putting it in close proximity to humans, animals and plants. I don’t think it has a place in landscapes.

Q. I have several Carolina Cherry Trees in my yard.  Last year the leaves began turning brown and flake off. Can you tell me why they are doing this and how I can correct the problem? Carolina cherry laurel and leaf drop A. Let’s get one thing out of the way before we begin. It is called Carolina Cherry Laurel for a reason. This plant is native to the humid, wet climate and rich soils of the southeastern United States. It is not native to dry, deserty climate and barren soils of the southwestern United States. It struggles here compared to the Southeast. This plant requires extra care on your part when growing it here. Carolina Cherry laurel and leaf scorch             Add 50% decent compost to the soil mix when planting. Dig and amend a hole at least three times the width of the container. Five times is better. If this wasn’t done at the time of planting, make vertical “chimneys” 2 feet deep and 2 to 3 feet from the tree trunk. Fill these “chimneys” with compost or a 50% mixture of compost and soil. Cherry laurel heat or water stress             Covering the soil with rock up to the trunk is a bad idea. It will work for a few years, until the soil amendment is gone, but eventually these plants will pay the price. No, I take that back, you will pay the price. Plants that begin their name with “Carolina” or “Japanese” are going to struggle in our Mojave Desert environment. Once in awhile someone puts it in the right location and adds enough soil amendments at planting. But it will go down with all that rock mulch around it unless compost is added regularly and watered in.             This doesn’t mean, “Don’t plant them!”. It means be careful where in your landscape you place them and how you grow them. Plants that do not belong in the desert require more investment at planting, long-term care and money to grow them here than in their native habitat.             After planting them in a 50% mixture of compost and soil, cover the soil beneath their canopy with wood chips 3 to 4 inches deep. Woodchips should cover an area at least equal to the canopy spread of the plant. This surface “mulch” will need a couple of inches of new mulch on top of it every three years or so. This is because the bottom layer “dissolves” or rots into wet soil beneath it over time.             This rotting of wood chips enriches the soil it touches and adds nutrients and biological activity to it. These are important ingredients to the long-term success of “alien” plants growing in our desert environment.             The discoloration and death along the margins of the leaves arises from a plant health problem. Improve the health of these plants and they will be more tolerant of our desert conditions. Additions of compost and woodchip mulch to the soil surface will help.             Make sure that these plants are getting enough water from at least four locations around the trunk. These emitters should be about 18 inches from the trunk in a square pattern with the trunk at the center. They should be giving these plants enough water at each irrigation. If these are drip emitters, they should be emitting water for enough minutes to allow it to drain 18 inches deep. Depending on the emitters, this could be 30 minutes to an hour.             Irrigation of large trees and shrubs should never be daily. Give large plants at least one day without irrigation so that water can drain from the soil and the roots can “breathe”. The roots of these plants are very susceptible to suffocation, root rot, when soils remain wet and cannot drain adequately.             The major problems with this plant, because it is so closely related to plums and peaches, are many of the same problems as fruit trees. When I look closely at the pictures you sent, which are very good and thank you very much, I see root weevil damage on the leaf edges. These are the notches that you see on the margins. These insects feed at night and are in the soil beneath the plant. There is not much you can do about them except perhaps apply a systemic insecticide around the roots after the plant has finished blooming. Use the Bayer insecticide if you go down this route.             I believe if these plants were in good health you would see little to none of this type of damage. I believe the plants would be very full and the leaves would appear healthy. Make sure you apply either wood chip mulch around the trees as I suggested earlier and combine that with a yearly application of a tree/shrub fertilizer in late January or early February. Only use mineral fertilizers if you have wood chip mulch surrounding the trees. Again, I repeat. This should not be bark mulch if you want to improve plant health.             Don’t get me wrong. There is nothing wrong with bark mulch. It can be very beautiful but it adds nothing to the health of the plants. It is purely decorative. Wood chip mulch, trees and shrubs that are shredded in their entirety and applied to the soil surface, improve plant health when they begin to break down/decompose a.k.a. “melt” or “dissolve” back into the soil.             Another problem with this plant is a plant disease called shot hole fungus. We see this leaf disease on peaches and plums when our humidity is too high. In climates with higher humidity, like some of those in California, this disease can be a severe problem. In fact, varieties of peaches and plums are grown in certain areas with high humidity strictly because of this disease problem. This disease causes spotting on the leaves and sometimes the leaf margins. As this disease worsens, sections inside of the spots die and drop

Q. What is the best way to get rid of white powdery mildew on my Euonymous plants? A. The best way is without using chemicals. This requires understanding the conditions which create powdery mildew. The conditions that create powdery mildew are high humidity, splashing water, shade, and lack of air movement across the leaves. Applying chemicals only circumvents the problem and doesn’t find a long-term solution to the problem.   Powdery mildew on Japanese euonymous and leaf death. If this advice is followed, there is no need for applying chemicals to control powdery mildew in our climate.            New location? Make sure your plants are in as much sun as possible. If this is not possible, you might consider a different location for these plants or planting new ones.              Splashing water. Do not let water from sprinklers splash on the leaves. Prune the plant to create openings for movement of air between the leaves. If there are trees above the plants, consider removing limbs of these trees that are creating too much shade so that more light reaches the plants.             Secondly, if these plants are receiving water from sprinklers, switch to drip irrigation. If these plans are being sprinkled with water accidentally, solve this problem so that the leaves do not receive water from sprinklers.              Prune for air circulation. Prune these plants deep inside their canopy and remove stems that are too close to others and allow more air movement or wind through these plants. As a last resort, you can use fungicides such as the sulfur based more copper based fungicides. Fungicides used control powdery mildew on roses should also work.

Q. I read with interest your article in the Sunday RJ regarding the mulching of fruit trees.  The article included the comment “Mulch was kept 12 inches away from the tree trunks.”  Why was that done? I recently mulched my fruit trees but surrounded the trees with red cedar mulch right up to the trunks. This larger pine tree died because wood chip mulch was piled against the trunk. A. It is kept away from the trunk because of people watering too often. If you are watering frequently, wet mulch against the trunk can cause a serious disease problem called collar rot. Keeping the mulch a short distance from the trunk helps keep the trunk dry.             It doesn’t have to be a foot away. It can be 6 inches away but 12 inches is easier for most people to gauge. Once the tree is older and the bark is thicker, this is seldom a big problem. But on young trees I strongly suggest doing it.

Q. Could you please explain why the pine trees surrounding the office complex called Quail Park IV at 2820 West Charleston planted right next to the buildings and surrounded by asphalt are so huge? Where are they getting the water?  Not on the Quail Park properties but pine surrounded by asphalt but doing well. A. Since I cannot verify this I will only speculate. But first let me tell you about another situation. Many years ago there were pines growing along the SW corner of Sahara and the Strip. The hotel/casino that was there was long gone but the pine trees remained. No irrigation. But they survived there happily for many years. When pine trees don’t get enough water the canopy begins to look very thin, sparse growth and the top of the canopy “flattens” and doesn’t get as tall as its well-watered brothers. We had a staff member in our office under my direction whose job was to answer questions much like the Master Gardeners do now for Cooperative Extension. This was pre-1990. Her name was Hobby St.Denis and who was actually a mentor of mine very early in my career. I heard her tell people to “not water so much. Look at the pines growing at Sahara and the Strip. Those pines have not been watered for years!” We knew about the shallow aquifer that flows from the NW of the valley to the SE. It is very shallow through much of Las Vegas. It is so shallow that parking garages on the Strip had to pump water out of the bottom levels so they didn’t flood! It is so shallow at that location the pines had all the water they wanted! No irrigation. I am guessing these pines at Quail Park are pulling water from the same aquifer. You can read some very boring research articles about this aquifer (I can say that because I was one of the authors) if you google “las vegas shallow saline aquifer” and read all about it. Be prepared for a good nights sleep!