Xtremehorticulture

Xtremehorticulture of the Desert

Acacia Dropping Its Leaves

Leave a Comment / acacia, borers, irrigation, sunburn /

Q. My young acacia tree has abundant growth but only on the top half of the branches. Each of these branches are losing many leaves half way up the branch. There is a lot of growth at the top of the tree but not much below. Am I watering too much, too little? I water every five days during the summer. A. Acacia trees are desert plants. Most desert plants are opportunists when it comes to using water. In other words, when water is present they grow like crazy. When water is absent, their growth slows and they then try to use as little water as possible. Desert plants may even stop their growth and drop their leaves when water is not available! This is not Acacia but Palo Verde. Boring insects, or borers, may feed on a variety of trees and shrubs or very specific ones. Borers, like the flat headed apple tree borer, has a variety of trees they attack including the desert trees. Sometimes they attack trees with sun damage and other times they seem to attack trees without any cause at all.             All plants are tremendous competitors for water, nutrients and light. They want to be “top dog” in their plant community by taking as much water, nutrients and light as possible when it’s available. By doing this, they take away these building blocks of growth from other plants.             When water is present, trees try to get as tall as possible as rapidly as they can before they start to fill out. They grow upward first and then put energy into horizontal growth once they’ve established some height. This growth in height takes away light and shades competitors. This early growth in height, when there is a plenty of water and nutrients, oftentimes is at the expense of putting on lower growth . We commonly see borers attack fruit trees and many different landscape plants. This flat headed Appletree borer infested a young Apple tree recently after was planted. The tree was so young that extensive damage was done by a single borer found feeding in the tree.             Watering schedules take two different forms; how much water is applied and how often water is applied. It’s difficult to say with certainty without seeing the tree, but it sounds like it is receiving water too often.             Watering every five days means nothing to me. I can take a sip of water hourly and someone might think I am drinking plenty of water. But another person might ask, how big are your “sips”? One teaspoon or 1 pint?             How much water to apply? When watering trees, give them enough. Apply enough water to wet the soil at least 24 inches deep. Apply this water to at least half the area under the canopy of the tree. Once it enters the soil, the water spreads horizontally further than this. Use 3 eighths inch rebar to estimate how deeply water has penetrated into the soil after an irrigation. Check the soil in 3 or 4 locations.             Use 3/8-inch diameter rebar that is three feet long. After irrigating, push this rebar in the soil in three or four locations to check the watering depth. Wet soil allows the rebar to slip in easily to the same depth as the wet soil. Dry soil makes it hard to push further.             It should slip into the soil at least 24 inches deep. Once you know how many minutes this takes, the amount of time you water won’t change. Each irrigation will be 24 inches deep.             If using drip irrigation, space emitters about 2 feet apart. If using a basin or moat under the tree, the basin should be as wide as half the area under the canopy. Trees grow. This means the basin must expanded every three years. If using drip emitters, add more emitters every three years. Basin under a tree used to capture the water for irrigation. If using a hose or some other delivery method that releases a large quantity of water rapidly, a basin is required to keep the water from going everywhere else but around the tree.             How often to apply water? Look at the tree canopy. It will tell you. When the canopy of the tree starts to thin out, it’s time to irrigate! Desert trees tell you when to water when their canopies begin to thin out.

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Moisture Meters and Rebar Tell You When to Water and How Much to Apply

1 Comment / irrigation, root depth, soil moisture, watering /

Q. Our water bill gets high in the summertime. I suspect we’re overwatering but don’t know. What strategy can we go through to determine when plants are getting just enough water. More than enough is hard to determine. A. There are 2 pieces of information you need when irrigating: how many minutes to run the irrigation timer and how often. This is the basic information that’s entered into an irrigation controller in a variety of methods. Irrigation controllers have all sorts of whistles and bells but that 2 pieces of information is what is needed. This requires a small investment on your part in the beginning. The two questions that need answering are when to water and how long (minutes) to water.  How often to water You will need some sort of moisture meter that measures soil moisture and a steel rod for determining how long to water. This is an inexpensive moisture meter you can buy for under $10 at any hardware store for nursery. They are made for use with houseplants and so they probably won’t last very long when you try to push them in our soils. But they are fairly accurate. Most houseplants should be watered when the meter shows a “6”. For houseplants use distilled or RO (reverse osmosis) water.              There are two types of soil moisture meters available. One is inexpensive you can buy at box stores for houseplants for less than $10. A better one can be bought online for $40 – $75, can be pushed into more difficult soil and lasts longer. I have purchased both the Reotemp and Lincoln soil moisture meters and the Lincoln lasted. The Reotemp fell apart after a few tries. This is the Lincoln soil moisture sensor and has had a solid workout for two years in tough Las Vegas soils. /The Reotemp soil moisture sensor broke after a few tries. The tip came off. Same problem was reported by another person to me. The tip was not secured to the sesnsor rod and it fell off. All of them have the same scale for moisture readings, 1 – 10. After calibration, recently watered soil will read 10 on this scale. Irrigate days later when the scale reads six. The expensive one lasts longer and can be used in more difficult soils, but it gives you about the same reading as the inexpensive one. How much to water How much water to apply or how many minutes on an irrigation controller requires a steel rod about three feet long. Use a 3/8-inch diameter steel rebar that is 3 feet long. They can be purchased at the major box stores for about one dollar. Shortly after the irrigation, push the steel rod into the wet soil in several spots. This is what the steel rebar looks like if you go looking for it in the store. You can get it at any box store/hardware store. Get the 3 eighths inch diameter rebar and select one that’s about 3 feet long. They will have them in various lengths. If you want to get fancy you can sharpen the end of it into a point on a grinder and bend the top over into a handle. But using it as is works just fine. Pushing this into the wet soil will tell you how deep the water has penetrated. It slips into wet soil easily but when it hits the dry stuff it’s hard to push. Lawns and flowerbeds should be irrigated to a depth of 8 to 12 inches. Large trees should be irrigated to a depth of about 2 feet. https://www.homedepot.com/p/1-2-in-x-20-ft-Rebar-REB-4-615G4-20/202532809             Steel bars slide easily through wet soil until they hit dry soil. Trees and large shrubs should have wet soil down to at least 24 inches. 12 inches is usually enough for most other plants including lawns and vegetables.             Water long enough, or apply enough gallons, to make the soil wet to the desired depth for all the plants on that circuit or valve. If some plants aren’t getting enough water while others are, add more emitters to those that aren’t.             The first two seasons you might have to measure soil moisture and use the steel bar five or six times to get a “feel” for when to water. But after the second year you will start recognizing a seasonal pattern to irrigating plants in your landscape and you will not need them as often. I bought both the Lincoln and Reotemp moisture meters on Amazon. The rebar I bought at Home Depot.

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Brown Spots in Lawn Probably “Frogeye” Disease

Leave a Comment / disease, Fusarium, grass, insects, irrigation, lawn, turfgrass /

Q. I have some large dead areas in my lawn. I don’t think it’s an insect problem. Watering is at 2 AM and 7 AM. This was my first lawn problem in 16 years! Unusual pattern for dead grass. Too random for irrigation I think. This picture you start to see the “frogeye” disease pattern. Looks like it could be a chemical spill. Here is where “frogeye” starts to make an impression. But its over.  A. I looked at the pictures you sent, but the last picture was the most “telling” to me. I think your lawn had a disease problem that is now finished. Don’t do anything now! Let me tell you why I came to that conclusion.             Insect problems here are not like those “rolling back like a carpet” problems described in books and online. Those descriptions apply to Kentucky bluegrass damaged by white grubs. We have grubs, but we don’t have much bluegrass anymore. Our lawns are 95% tall fescue and tall fescue reacts differently to insect damage. It pulls out like loose hair from an old animal skin. Plus, the pattern of dying grass does not resemble insect damage. Rolls Back Like a Carpet             I first thought the brown spots were an irrigation problem, but the pattern doesn’t fit an irrigation problem. With irrigation problems, dead or damaged areas are in a pattern that relates to the location of sprinkler heads. I didn’t know where the sprinkler heads were, but the damage was irregular, so I ruled out irrigation. Irrigation problems are nearly always easy to see how they connect to the sprinklers.             The pattern does, however, resemble a chemical spill flowing downhill and damaging the grass in its path. It was a possibility, but the last picture looked like advanced stages of a disease problem. We used to call this disease Fusarium blight or “frogeye”. This disease has since been renamed Necrotic Ring Spot. I thought “frogeye” was much more descriptive. Seldom will you see it this obvious but this is frogeye. See how it got its name? In advanced stages these dead areas can become one but you still look for little patches of green grass that would still be there. Sometimes its hard to see them.             What led me in the direction toward disease were the small patches of green grass still alive but surrounded by dead grass. These small green patches of grass are how “frogeye”, now Necrotic Ring Spot, got its name.             From the pictures, it looks like the disease has run its course and the grass that’s alive is healthy. I say this because the grass surrounding the dead areas appears healthy. This is the way lawn diseases usually work. They have a window of opportunity, when the weather is right for the disease to spread, and it takes off. The weather changes and the disease stops.             You would be wasting your money to apply a fungicide now that it’s over. But, don’t disturb the brown, dead grass and leave it alone until fall. If you remove it now, it opens the soil to invasion by Bermudagrass. Bermudagrass loves sunshine, bare soil and water. It hates shade. Wait until the weather cools in late September or October, remove the dead grass and either seed or sod these areas.

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Avoid Salt Mayhem By Using Good Irrigation Managers

Leave a Comment / irrigation, salinity, salts /

Determining the best irrigation schedule for a mixture of landscape plants is difficult enough but when salinity is involved, either in the soil or in the irrigation water, it complicates matters. Let’s cover some irrigation do’s and don’ts and see how salinity might affect the way we irrigate. Avoid Daily Irrigations Except for shallow rooted plants like lawns, annual flowers and vegetables in raised beds, daily irrigations should be avoided any time of the year. Many turfgrasses and annuals have root systems that extend into the soil 12 inches or less. During the heat of the summer and under desert conditions some of these plants may require daily irrigations. The deeper you should water. Lawns, annual flowers and annual vegetables have the shallowest roots and need to be watered the most often. The concept of irrigating nondesert landscape plants is focused on wetting the root system to its entire depth, allowing the soil to drain and re-wetting the soil again when half of this water has been used by the plant or evaporated. The Amount of Water Applied Varies with the Size of the Plant So we can see that the volume of water applied in a single application is directly related to the depth of the root systems of plants. When designing a landscape irrigation system we try, to the best of our abilities, to put plants with similar rooting depths on the same valve or station. Create irrigation zones in your landscape that reflect the needs of the plants in it. This is because the only way to water less or more often is to turn the valve to that irrigation line on or off. This is done with the valves. So each valve should represent different irrigation depths in your landscape; trees and large shrubs, smaller and medium size shrubs and small plants. Other valves could include annual plants and lawn and desert adapted plants which don’t need to be watered as often. You could even create another zone just for cacti. (This diagram originally appeared in Sunset magazine many years ago demonstrating Hydra zoning or mini oasis landscaping) More often than not we are handed an irrigation system with a mixture of plants that have a variety of rooting depths. When deciding an irrigation schedule for a single valve or station we generally have two options; set the number of minutes based on the average rooting depth of all the plants or let the plants with deepest root systems dictate the number of minutes of station runtime. Do We Conserve Water or Minimize Plant Problems? This decision depends on whether to conserve water or minimize landscape problems. When we decide to under irrigate some plants so the majority receive the correct amount of water, we may see some plant damage. If the under irrigation is not severe, we may see the slowing of plant growth, a decline in density due to leaf drop, leaf tip or burning of leaf margins. When plants are severely under irrigated then we begin to see branch die back and in some cases death. This is a mixture of a mulberry tree with cactus growing underneath it. Water the mulberry tree and the cactus gets over irrigated. Water only for the cactus, as this was done, and the mulberry doesn’t get enough water. Under irrigating, or applying less water than dictated by a plants rooting depth, can also impact safety issues. What happens if we under-irrigate large trees such as pines which have shallow roots to take up water but require deeper roots to anchor it in the soil? Current irrigation technology is based upon time management and varying how water is applied to plants. This technology varies the amount of water applied to plants by changing the number of minutes valves are open, increasing or decreasing the points of water emission or changing the rate of water applied at the point of emission. This translates to increasing or decreasing the number of drip emitters, bubblers, nozzles or spray heads or substituting old points of emission for new ones that have different rates of application. This is a highly sophisticated Hunter ACC irrigation clock. These types of irrigation clocks are expensive but give you a tremendous amount of flexibility. They wouldn’t be good for small landscapes but an excellent choice for large landscapes that have a lot of irrigation variability. Making these changes to an irrigation system that was designed by a professional and focused on the uniform application of water, more than likely will make the system less uniform and less efficient. This will likely result in substantially higher water usage. These types of alterations to professionally designed systems must be done with care. These six station inexpensive irrigation controllers are fine for most small landscapes that don’t require a lot of flexibility. When to Make Changes in the Irrigation System? There are some obvious cases where changes must be made. For example, changes must be made when some plants are receiving excessive amounts of water or not enough water while others on the same valve appear to be watered adequately. As plants get bigger, they need more water. When plants get bigger, their tops get bigger as well as their root system. Increasing plant size requires the application of higher volumes of water. Increased plant size dictates that the area irrigated under the plant also needs to be increased. Logic tells us we need to increase the amount of water by applying it to a larger area. Just because a few plants on an irrigation valve have grown larger seldom requires increasing the number of minutes of runtime. Other plants on the same circuit that received adequate amounts of water would then be over-irrigated for the sake of a few. Is Increasing the Number of Minutes the Right Decision? Of course increasing the number of minutes is the easiest solution to the problem but is it the right one? The quick fix of bumping up the number of

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Bermudagrass Lawn Change of Color May Be Drought

Leave a Comment / brown patches, dead areas, drought, grayish green, irrigation, lawn, turfgrass /

Q. We have lived in the same house in Las Vegas for the last 42 years and every June my lawn has the same problem. The lawn is a mix of common and hybrid Bermudagrass. First the grass turns grayish (in patches) and then it turns brown. It slowly comes back by September. I water according to local recommendations, use Scott’s Turf builder 3 to 4 times a year and use Ortho Bug-B-Gone insect granules twice a year.   A. If this were tall fescue I might be tempted to say this is a disease problem. However, since it is a mixture of Bermudagrasses I think this is an irrigation problem. This will be particularly true if these problem areas are in the same locations every year. Turfgrass or lawns will turn a smoky or grayish green when they are not getting enough water. This is because the leaf blade either folds in half or roles depending on the grass. This creates a different color; smoky or grayish green             Bermudagrass in our climate doesn’t develop many insect or disease problems.             The success of lawns in our desert climate is directly tied to the quality of an irrigation system. In technical terms we say the irrigation system should provide head to head coverage; water from a sprinkler head should be thrown far enough to reach the head to its right and it’s left. If we don’t provide this kind of uniformity in the design and installation of an irrigation system it can result in brown patches that don’t receive enough water. A close-up of the grayish green color where the lawn is not getting enough water             The water pressure in the sprinkler system should fall within a range recommended by the sprinkler manufacturer. If the water pressure is too high or too low it will affect the distribution of water and create browning of the lawn in the same areas year after year. Otherwise, there are sprinklers now that will lower the water pressure before the water is applied to the lawn. Another indicator of drought or lack of water in a lawn are footprints. If you walk across grass that needs water, look behind you. If your footprints remain in the grass does not spring back quickly, the grass needs water.             You can correct this problem in the short run by increasing the number of minutes that you apply water. This delivers more water to the dry areas. Unfortunately, it also delivers more water to the wet areas resulting in overwatering of the green areas.             It is also a good idea to punch holes in the lawn with an aerating machine in the spring, particularly in the brown areas. This helps water to move into the soil and not run off into low spots if there are any.             Bermudagrass is notorious for building up “thatch”. Thatch is a buildup of old grass stems and debris under the surface of the lawn but on top of the soil. Years ago this thatch was burned off of the lawn with fire. We can’t do that anymore. We must do it mechanically now. A core aerifier for lawns pulls plugs or cores out of the lawn that are about 4 inches deep. This type of verification provides better drainage and water penetration for lawns suffering from drought             It is important to dethatch Bermudagrass each year. This is usually done in the fall when overseeding it with a cool season grass like ryegrass to maintain a green winter lawn. If the lawn is not overseeded in the fall then thatch can be a huge problem in Bermudagrass. D thatching machines, sometimes called vertical mowers, pull debris from a lawn which allows water to better penetrate the soil and reduces runoff.             Making changes to the irrigation system will correct some of this problem and reduce the amount of water needed to keep the lawn green. Increasing the number of minutes you apply water during the heat of the summer should solve this problem in the short run.             But I would combine this with lawn aerification every three or four years and dethatching every year to improve the amount of water entering the soil in the dry areas.

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Big Plants Use More Water than Little Plants

Leave a Comment / irrigation, plant water use /

Q. My wife believes 30 ft. pine trees do not need watering because they absorb water from the air. I ask you because the pine needles are turning brown Is she correct? A. She is not correct. As any tree or plant gets bigger its demand for water increases. They do not take water from the air. Just the opposite. They lose water to the air in a process called transpiration, the same as any other tree, needled or with broad leaves.

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Turfgrass Dead Spots. Irrigation Problem?

Leave a Comment / brown spots, drought, irrigation, sprinkler problem, watering problem /

Brown spots or dead areas in lawns can be common during summer months. It might be a disease, but then again, it could be something else. There is a sprinkler head in the center of the green spots. The three primary reasons that lawns develop brown spots or dead areas are due to irrigation problems, the development of diseases and insect damage. Irrigation Problems. How many times have I heard, “I know the sprinkler system was installed right. I did it myself.” Just because you did it yourself, does NOT mean it was done correctly. If it was done correctly did you design it for “head to head” coverage? Did you size your pipe taking into account all of your nozzles gpm and friction losses? Did you make sure the pressure of your  First sign of an irrigation problem is that smokey-grey color in your lawn when it gets hot. system falls within the manufacturers recommended pressure range for your nozzles? I can go on. If you understood these terms and took them into account then maybe you did it right. Pressure too high. Sprinkler in the center of that little green spot of grass Any weaknesses in your sprinkler system will show up when temperatures hit 110F and 15% humidity. Lawn water use will exceed 4/10 of an inch of water every day. The first thing you will notice when temperatures start to get hot are smoky-grey patches start to show up in your lawn. Then the brown spots or patches start to appear and they are often not clearly defined. Oftentimes they are smack dab between the irrigation heads when heads are not spaced appropriately, nozzles are mismatched, heads are not perpendicular to the lawn or you use 2 inch popups when you should use 4 inch. Sometimes these brown patches can be right next to the head if the pressure of your system is too high and the sprinklers “fog”. In order to clear up the problem or you use the wrong type of nozzles. Little bit of drought and disease mixed in this lawn. ·       Know the operating pressure of your sprinkler system. ·       If mowing at two inches or above use four inch popup sprinklers. ·       Space sprinkler heads and select the right nozzles to provide head to head coverage (water from one nozzle should reach the neighboring nozzle and vice versa). ·       Size irrigation pipe to provide water flow through the pipe not to exceed 7 feet per second when operating. ·       Use a system pressure regulator (if operating pressure is to high) or a booster pump (if operating pressure is too low) so that operating pressure falls within pressure range recommended by sprinkler nozzle manufacturers.

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How Much Water for My 1 1/2 inch Diameter Fruit Tree?

Leave a Comment / desert, fruit tree, irrigation, Las Vegas, mohave, mojave, PET /

Q. How many gallons should a fruit tree receive for each watering if it’s trunk is 1.5 inches in diameter 24 inches above the ground? A. Watering amounts are usually related more to the size of the canopy or total height than the trunk. Trunk size is sometimes used more for estimating how much fertilizer to apply.             That tree size would require around 10 to 15 gallons for each watering. If you are using drip emitters, you should be using four (4) emitters in a square pattern 12 to 18 inches from the trunk. So running 3 gallon per hour emitters for one hour would equal 12 gallons. Just to remind readers we follow the PET curve developed for here and is below. Months are January=1 to December=12. Numbers on top of the bars represent inches of water per day. We would change irrigation frequencies in months 2, 5, 7, 8, 10 and 12.The amount applied each time stays relatively constant, just the times per week is changed.

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Saguaro Leaning is Usually an Irrigation Problem

Leave a Comment / cactus, giant, irrigation, Las Vegas, Mohave Desert, Mojave Desert, nevada, planting /

Q. Our saguaro is about 10 years old.  In the last year or so four arms have popped out mostly on one side.  Now the saguaro is beginning to lean and we have propped it up. What do you suggest we do? Even though this picture is not from the submitter I wanted to post it for my friends who are viewing from other countries or part of the USA. Saguaro is not native to the Mojave Desert but to the Sonoran to our south. Even though they can be a bit sensitive to the Mojave winter cold they have done quite well in the lower elevations of southern Nevada. If people will stop putting burlap coats on it for the winter….. A. I would guess your irrigation is too close to the trunk. This concentrates the roots there and doesn’t allow root development further from the trunk for support.             In the wild, saguaros roots are about 30 inches deep near the trunk and spread a distance equal to its height at depths averaging only about 10 inches.  This matting of shallow roots spreading from the trunk is important in keeping the cactus erect.             I would prop it up as you are doing and immobilize the base so it cannot move. Then I would apply water at increasing distances from the trunk. These should be shallow and infrequent irrigations at distances from the trunk equal to at least half of its height.             You can do this by planting other desert plants that require similar types of irrigations in these areas. Water supplied to these plants will help to irrigate the saguaro. You can also do this by handwatering in these areas once a month with a spray nozzle.

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Thanks to Hunter for Advanced Irrigation Control at the Orchard

Leave a Comment / hunter irrigation clock, irrigation, Las Vegas, Mojave Desert, nevada, north las vegas, watering at the orchard /

A really big thanks goes out to Hunter Industry and in particular Nate Gould out of Phoenix, Arizona. Nate offered to provide the UNCE orchard in North Las Vegas with a state-of-the-art Hunter ACC Irrigation Clock. This definitely brings the UNCE Orchard into the 21st Century! Hunter Irrigation’s ACC Irrigation clock. Top of the line for all of the UNCE Orchard’s irrigation needs. Nate helped us install it so we that really cut our installation time down. (Advanced Commercial Controller) to help us better manage our irrigations for the fruit trees and vegetable plots. Our volunteers can communicate with the clock remotely so if we have an irrigation problem we don’t have to keep running back to the clock.

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