Soft and rotting trunk of young peach tree. Definitely borers. Young fruit trees like peach and apple are very susceptible to borers in the desert and oftentimes don’t survive a one time attack. Older trees can recover better. Q. I recently planted a 15-gallon peach tree that I had in a planter pit all winter. I noticed that the bark was soft and almost rotting at the joints with some sap coming out. I am afraid that this can be borers but can’t say with certainty. A. Judging from the picture you sent with all the dried sap coming from the tree and given it’s a peach, I am 100% certain this is borer damage. This damage started last year. Borer adults in southern Nevada  are beetles that fly and don’t bother a tree until it’s time for the female to lay its eggs. Sap oozing from a newly planted fruit tree after a rain from borers.             Adult beetles lay their eggs on all sorts of weakened and newly planted trees and shrubs, mostly on parts of the tree at least 1 inch in diameter and in full sun. The tiny larva from the egg tunnels inside the plant just under the bark, protected from predators and usually in the spring. Here it feeds on the rich sap it finds transported from the leaves and roots. As it continues tunneling and feeding under the bark, it gets larger as it creates more and more damage from feeding. If the borer hasn’t girdled or gone most of the way around the trunk or limb sometimes you can save it without an insecticide by removing all the damaged area with a sharp, sanitized knife.             The most susceptible plants in our hot and dry desert are the small and newly planted trees and shrubs. These borers prefer fruit trees and landscape plants in the Rose family. This includes most common fruit trees and many different landscape plants. Probably peach is the most susceptible. Plants will oftentimes produce new growth or suckers below the damage from borers or from its base.             Once these plants get large enough to produce their own shade then borer problems lessen until they get a bad pruning job. Bad pruning jobs open them up to sun damage again and it starts all over. Pyracantha dieback from borers. Don’t expose the trunk or limbs to direct sunlight in the desert on these plants.             What to do? Because they are hidden from site when tunneling inside young trees,  borer larvae are difficult to find. It’s easier to see their damage the day after a rain and the tree is sopping wet. Oozing sap from the trunk and limbs in areas exposed to intense sunlight is a pretty clear indicator of borer damage. Take a sharp, sanitized knife and surgically remove the young larva. It’s been suggested to soak the tree with a hose and water if it hasn’t rained. There he or she or it is! Sometimes when you excavate the damaged area with a sharp sanitized knife you will see them busily eating away at the soft juicky rich sapwood just under the bark.             Systemic insecticides applied to the soil around the tree will kill this larva inside the tree without using a knife. The most effective insecticide for doing this job as the insecticide “imidacloprid” listed in the ingredients. One example is the Bayer product referred to as “Tree and Shrub Insect Control”. Read the label on how to apply it as a “soil drench”, protect your hands and eyes, and follow the directions exactly for best results. Remember insecticides are a LAST resort when you have no other choices left. Apply imidacloprid as a soil drench (ingredient on the label) after the tree has flowered to protect honeybees.             I caution people to apply it after the tree or shrub has finished flowering in the spring. Because it is a systemic insecticide that can last for several months, I also caution people not to eat any fruit harvested for 12 months after its application.

Q. We have Buffalograss for a lawn which we overseed every winter with ryegrass. We applied the ryegrass late this fall and it didn’t come up, but  weeds did. Now our Buffalograss lawn is covered in weeds. Is it possible to apply a “Weed and Feed” product to kill all the weeds and not hurt the Buffalograss?  If so, what would you recommend and when should this be applied? Weeds growing in Bufflograss not overseeded. Closeup of the weeds. Many very early spring weeds are winter annuals like the mustards. They are easily killed but don’t let them go to flower and seed! A. Buffalograss, like Bermudagrass, is considered a “warm season grass”. It is native to the Great Plains of the US has a reputation for low water use. All warm season grasses are brown in the winter because they are dormant due to cold weather. As their name suggests, warm season grasses prefer growing in warm or hot climates. Besides Bermudagrass and Buffalograss, other warm season grasses include zoysia, Paspalum, and St. Augustine grass among others. These grasses are sometimes called “southern grasses” because they are used primarily in southern states.             Warm season grasses start turning brown in the cool fall months sometime in November and are totally brown here by December. Seeding a “cool season grass” like ryegrass into a “warm season grass” as its transition to dormancy is happening, creates a green winter lawn. You have two lawns in one during the winter; a green lawn actively growing in a brown lawn that is “sleeping”. The key for successful “winter overseeding” is good timing. A winter lawn of cool season grass is seeded as weather begins cooling off in the fall but you can’t wait until it’s cold.             The time for winter overseeding in this climate is between the end of September and mid-October. Your November timing was too late. If you have a warm November it’s possible to make it but that’s not what happened. Last November was a cold month with unusually freezing temperatures around midmonth. It was too cold for successful overseeding.             Estimating when to overseed a lawn is like estimating when to put out tomatoes in the spring only in reverse. Pay attention to the current weather and weather predictions for the coming two weeks. If it’s unusually warm, delay overseeding a couple weeks. If a cold front is coming in then you better get busy and overseed.             Warm season lawns like Buffalograss start to “wake up” and grow when it gets warm; March or early April here. Since the Buffalograss is dormant now (brown) any weed killer that kills green growth will not harm the dormant lawn. The usual weed killer used for this purpose is glyphosate. Mow these weeds but apply the weed killer in early March. A week or so after this weedkiller has been sprayed, mow the lawn short, fertilize and water it to encourage faster green up.

Q. I have a 5-year old Prickly Pear cactus. I brought it here from Florida in 2015 and started it by planting the pads. I’m seeing some yellowing starting to develop where the spines are located. I am familiar with cochineal scale and I don’t think it’s an insect problem. What’s causing this and how do I correct it? Damage to the cactus. Perhaps from cold temps. A. Most likely this is cold damage from low winter temperatures. Most of Florida is warmer than our Las Vegas climate. Your prickly pear cactus from Florida has never seen temperatures as cold as we get in Las Vegas. Prickly Pear, a.k.a. Opuntia cactus range in their tolerance to freezing temperatures from damage seen at 32° F down to 10° F. It depends where that cactus was originally growing. This is the type of freeze damage that I am used to seeing on prickly pear cactus. These were nopal cactus from Sonora but grown in Las Vegas where winter temps were just a bit too cold for them.             Opuntia cactus are native to Central and North America with some types growing in the warm Sonoran Desert and others in our colder Mojave Desert. Pads used for propagating this cactus coming from the Sonoran Desert will not tolerate the freezing temperatures of the Mojave Desert. But Opuntia grown from pads taken from the Mojave Desert will. Next spring growth may come at the center of the pad after winter freeze damage.             In the future don’t apply any fertilizer to tender Opuntia after July 1. Not applying late summer or fall fertilizers improves their ability to withstand freezing temperatures. For a similar reason, start withholding water from Opuntia to slow their growth in the early fall months. Not encouraging new growth by withholding fertilizer and water helps to hardened them off for the cold winter months.

            Sharpening a lopper is important so that the plant is not torn when cut. Would you let your doctor use a needle or scalpel that was just used on someone else? It is important to clean and sanitize ALL pruning tools. I like isopropyl alcohol. Here are alcohol wipes. Use a spray bottle of alchol if you want. The Best Time to Prune I had a college professor who taught the best time to prune was when the pruning tools were sharp. It was a little bit of a joke because most people believe the only time to prune plants is during the winter. That’s true if you’re using a chainsaw, reciprocating saw, hand saw or loppers but if you’re using a hand shears my old college professor’s advice was on the mark. If you’re using a hand shears to remove some offensive plant growth you can do it any time. Just make sure its sharp. My pruning classes always begin by adjusting, sharpening and sanitizsing ALL pruning equipment! Sharpen, Adjust and Sanitize If you’ve ever taken  my classes on pruning you know that I’m a stickler for three things when preparing to prune; adjusting a loppers or hand shears so it doesn’t rip plants instead of cutting them, making sure the blade is sharp for the same reason and sanitizing these blades. You wouldn’t go into a doctor’s office and let him or her use a dirty needle or scalpel. The same holds true for plants. Advanced stage of fire blight dieasese, one of many plant diseases passed along from plant to plant by dirty pruning equipment.             Chances are when using dirty tools five times out of a thousand nothing will happen. We use the same logic for protecting ourselves with insurance; it won’t happen to me! In 50 years of pruning plants I have seen an actual problem develop from dirty tools perhaps five times. But I have seen unexplained problem diseases develop later to pruned trees and shrubs many other times. The usual fault is claimed to be from “borers”. Was it? Sanitize Your Pruning Tools!             There are at least eight plant diseases I know of that can be transferred to plants through pruning cuts using dirty tools. There are probably more than this. Once a saw, loppers or hand shears is sanitized it is always placed back in a scabbard, draped around a neck or hung on a neighboring tree but never laid back on the ground. Six of those eight diseases can come from laying sanitized tools on the ground after they’ve been sanitized.             What to use for sanitizing equipment? I prefer spraying the blade with straight isopropyl alcohol, bought just about anywhere, after the blades have been washed with soap and water. Some people prefer bleach but if you use bleach then oil all the metal parts, so they don’t rust. In a pinch, I will wash the equipment and use a butane lighter to heat the blades. That works as well.             Do you ever wonder where lawn diseases come from? Later in the season we will talk about sanitizing lawnmower blades. Lawnmower blades are terribly dirty and can spread lawn diseases from yard to yard as well.

Desert landscapes don’t have to be all cacti and rock. How does a desert landscape design differ from Xeriscape? Or does it?

Q. When should I prune a “salad” tree?  Mine has 5 varieties of lemons and 2 oranges and is almost 5 years old.  I am afraid of pruning the wrong branches and affecting the varieties and yield. A. Pruning a “salad tree” is more difficult than a fruit tree with only a single type of fruit growing on it. Think of your “salad tree” having different fruit growing on it, all sharing a common trunk or large limb. When pruning, it is important to remember that each type of fruit growing on that tree needs its own space.               Some types of lemons and oranges have stronger growth than others. Your job when pruning is to prune back the strongest growth of those varieties so that the weaker varieties can survive. Otherwise the weaker varieties will die out from competition and only the strongest growing varieties will survive. This is the main reason why “salad trees” end up with two or three varieties that survive after a few years.             Your job is to be the chief mediator or referee when pruning. Surrounding strong growth needs to give up space through pruning so the weaker varieties have a chance at survival. When you bought the tree, each of the varieties had a label so that you knew where they were located. It’s important to keep these labels up to date so you see where different varieties are located. This helps to create space for new growth when pruning. It also teaches you which varieties are stronger than others.             Citrus, in general, is easy to prune. Pruning is done immediately after harvest. Any suckers are removed from the main trunk up to a height of about 18 inches. The canopy, or top of the tree, does not need extensive pruning. If crossing limbs are found, the offensive limb is removed at the trunk or a major limb. If a limb is growing on top of another limb, one of them is removed in the same way.             Rather than a “fruit salad” tree for small landscapes I prefer to grow individual trees planted close together; sometimes referred to as “planting in the same hole”. These individual trees are pruned separately so that they occupy their own spaces. The result is the same; smaller harvests at different times of the year but the pruning is much easier.

Q. Is it possible to grow azaleas in the Mojave Desert?  We want to get more color in our yard and having lived in the east for many years we know that azaleas add an abundance color in the spring. I have terrible soil so I know I would need to drastically amend the soil. Suggestions or comments? A. You can grow any plant in the Mojave Desert including azaleas. It’s a matter of how much you want them because plants that don’t belong here, like azaleas, cost more to maintain. These non-desert plants struggle in our climate and force you to take care of them if you want them to succeed. My second point is that your “sense of place” has never changed. You are still thinking like an Easterner. You live in the Mojave Desert now. It’s time to adjust. Sense of Place             Your sense of place relates to where you think of as home. I remember moving from the Midwest to the dry Western states many years ago and missing all the “greenery”. After adjusting to this new “home” I found all of the “greenery” hurting my eyes on return visits. It was just too green. After an adjustment period, my new sense of home was the dry Western United States, the different shades of brown, pink, purple and yellow I saw in rock. Plants were found sparingly. Desert Color             Before I tell you how to grow an azalea here, consider desert perennials that grow easily in the desert and add color. They are easier to grow, require less frequent watering and still provide a great deal of seasonal color. I am talking about  colorful plants such as penstemon, sage, salvia, and others. Many of these desert or desert adapted perennials provide a great deal of color at different times of the year and most like lots of sunlight! Some websites to visit on small plants for color: SNWA plant searchable database AMWUA Plants for Arizona Landscapes Native Plants for Utah and Western Colorado Red Penstemon             A good place to look for these plants is online before you go shopping. Get familiar with these names of desert perennials because it can get confusing at the nursery. Try looking online at the Southern Nevada Water Authority (SNWA) searchable database of plants and Arizona’s AMWUA (Arizona Municipal Water Users Association) database. Become familiar with their recommended plant lists and the plants they recommend. Once you do that, then it’s time to go shopping! Growing Azaleas             Now to your azaleas. Azaleas are considered an ericaceous plant. This means they prefer acidic soils, not alkaline desert soils. Prepare to add a chemical amendment to the soil to acidify it such as aluminum sulfate. Aluminum sulfate is much more powerful in its soil acidification properties than soil sulfur. You will probably need to add it to the soil once or twice a year to adjust the alkalinity. One of the ways that azaleas tell you there is a soil problem is by its yellowing leaves or a brown “scorchy”  edge.  By the way, if you end up using sulfur to lower soil alkalinity, make sure it is a fine sulfur powder and not sulfur granules, sometimes called soil sulfur. The sulfur powder reacts much faster with warm, wet soil than soil sulfur as granules. Try Brooks Hybrid Azaleas (red and white) developed in the Modesto area for the hotter drier climates. Another possibility are the Indica Hybrid Azaleas which are supposed to be more tolerant of sunlight.             Azaleas also like lots of woody debris, leaf litter and organic soils. So, using compost as a soil amendment and covering the soil with woodchips will be a good first step. Select a cool microclimate in the landscape that is shady but still bright. Azaleas NEVER like intense sunlight. North exposure or early morning sunlight with shade the rest of the day might be a good choice. Filtered light is preferred, never direct sunlight. Under the shade of a tree but lots of reflected light is a good spot.             Stay away from planting azaleas that were gifts in pots. These are “greenhouse azaleas” and not a good choice for our landscapes in most cases.

Look for Borers  It rained most of the day last Saturday in Las Vegas. The following Sunday would have been an excellent time to look for borers in the trunk and limbs of in landscape plants. Their presence would be announced by sap oozing from these infested, but water-softened, locations even though no visual damage is apparent. If you see sap oozing from landscape plants and fruit trees, it’s a good time to dig into those areas with a sanitized knife to see if you can find this critter and remove it. This will prevent it’s continued damage this spring and summer.  Otherwise you might find a dead limb or two or worse in July or August. Sap will ooze from borer infested trees and its gooey Mushrooms are Normal             After a rain mushrooms appear in a few days wherever wood is rotting on the surface of the soil or underneath it. You’ll see them popping up through woodchip mulch and where dead roots of trees might have rotted. Water helps dead wood rot and disintegrate into the soil where the mushroom mycelia grow. This rotting adds organic matter to the soil, encouraging roots to grow and causing it to become dark brown and rich.             Just like desert wildflowers, mushrooms pop up quickly to spread their “seed” everywhere in a couple of days after a rain. These mushrooms stay fresh only a couple of days before they mature and die. Sometimes “mushrooms” form beneath the soil, like huge fleshy alien balls, and then pop open at the surface releasing their spores. As soon as you see these mushrooms, knock them over with a rake or smash them with your foot. Pet dogs have reported to become sick if they eat them. A little bit hard to see but these mushrooms popped up everywhere in the woodchip mulch. Mostly stems left now. The caps are nearly gone. Underground mushrooms like this one can pop up from the ground after a rain. When dug up these fleshy underground mushrooms may look like this. Irrigate Away from Cement             Rain changes everything in the desert. Desert soils are dry soils and not meant to be constantly wet. When desert soils become wet I think of them as “unstable”, both structurally and chemically. An infrequent desert rain is not a problem. But when irrigation water is applied over and over to a soil that is normally dry, these soils shift, collapse and chemically change. In urban landscapes this can be potentially destructive.             This is the reason for keeping irrigation water 3 feet away from the foundation of a home, patio, driveway, wall or sidewalk. Corrosive salts are in the soils and irrigation water. These corrosive salts will “eat away” at cement and steel. Salts in the soil dissolve when water is present causing the soil to collapse over time. Water dissolves these salts and carry it as far as it reaches and then deposit it in straight lines or circles. When the same amount of water is applied over and over, the salts are deposited to the same spot each time. These are the white rings and lines you see on cement and block walls. Salt in the water or soil or fertilizers can eat away at concrete, even the so-called resistant Type 2 and Type 5 Modified Dissolved salts can creep up walls from being continuously wet. Eventually they will eat away at the blocks and mortar joints.

There is some shared greenhouse space available to rent. The greenhouse is the old Dave Turner greenhouse now located near Boulder Hwy and Tropicana. It is 30 x 90. If interested contact Mark at [email protected]

In this interview with Rafael Evangelista you will learn about a love affair with a highly successful fruit that does astoundingly well in our Mojave Desert climate.