Ash tree in arizona

Arizona Ash Tree Information

Fraxinus velutina, also called Arizona ash or velvet ash, is a deciduous tree native to Texas, Arizona, New Mexico, California, Nevada and Utah, where it grows in canyons, along desert stream banks and near moist washes. Arizona ashes are commonly planted as shade trees in residential lawns and parks, in parking lot islands, and along highway medians or roadsides.


Arizona ash trees vary in height from 30 to 50 feet, with a 45- to 60-foot spread depending on their growing conditions. They have spreading, open crowns and single or multiple trunks with deeply furrowed bark. Their opposite green leaves turn yellow in the fall; the leaf shapes vary depending on the tree. Arizona ash trees produce ornamentally unimportant green or greenish yellow flowers, according to Edward F. Gilman and Dennis G. Watson from the University of Florida IFAS Extension; tan or green winged seed pods replace the flowers.

Cultivating Arizona Ash

Arizona ash trees can grow in a variety of soil types. These trees have a high tolerance for drought, but they can also grow in wet or poorly-drained soils. They propagate easily by seeds, as well as grafts and cuttings. They can tolerate desert and alkaline soil. Several Arizona ash cultivars include Modesto and Rio Grande fantex ash. They prefer full sunlight, although trunks may be susceptible to sun scald in harsh desert environments if they have light canopies.


Arizona ash trees have a rapid growth rate. This encourages the development of surface roots that damage surface structures, such as sidewalks and walkways. The trees are difficult to maintain because multiple trunks often form from the main trunk. This creates weak trees that break easily at the base. They also require regular pruning to keep their branches from breaking or dying. They tend to be messy, and leave seed pods and leaves on the lawn. Arizona ash trees only survive for 25 to 30 years before dying.

Pests and Diseases

Arizona ash trees are susceptible to attacks from aphids and scale insects. Aphids have small, pear-shaped bodies, and vary in color depending upon the species and what the insect has been eating. Scale insects have round or oval-shaped protective coverings over their bodies. These insects drain sap from plants but rarely cause serious damage. The Verticillium dahliae and Verticillium albo-atrum fungi cause verticillium wilt in ash trees. The fungus attacks the roots and releases toxins that clog up the tree’s water transport system, causing discoloration in the sapwood, branch dieback and tree death.

Houston: Root barrier for neighbor’s Arizona ash tree?

From: Houston

Question: There is a huge Arizona ash tree in my neighbor’s yard. Its trunk is about 27 feet away from the foundation of my house and its foliage reaches my roof. I am planning to dig a trench on my side of the fence (about 15 feet from the trunk) and install a root barrier. How deep is the trench supposed to be? What is the best material for root barrier against Arizona Ash? And, how long should the trench be? Thank you.


Fraxinus velutina (velvet ash), also called Arizona ash, is native to far West Texas, but not to the Houston area. We really don’t think you need to worry about those roots as much as about the branches touching your roof.

While it is certainly true that tree roots can grow up to three times the spread of a tree, the problem in foundations is soil subsidence. The tree root does its part on this by looking for water and sucking it up, but if the soil is dry, the foundation is probably going to drop and shrink anyway, and that is much more likely to cause the foundation damage then the tree roots. There is really no way to tell a tree to grow in another direction, and the branches against your roof can definitely cause problems. Insects, not to mention squirrels and raccoons, consider tree branches against a house as an open invitation to come in, have a bite to eat, and spend the winter. Certainly a trained arborist could prune the branches away from the house, but when you prune a plant, where does the new growth appear? Right, it appears in the area you pruned. We think your first step would be to confer with your neighbor on trimming his tree branches back away from your property.

In terms of whether or not the roots will harm your foundation, you can read the recommendations from Iowa State University Extension Service for Sidewalks and Trees which bases the distance trees should be planted near pavement or other concrete structures on the mature height of the tree. Fraxinus velutina (velvet ash) is a small to medium-sized, deciduous shade tree, usually no taller than 40 ft. in cultivation. Their recommendations are:
1. trees with a mature height of less than 30 feet, 3-4 feet from pavement,
2. trees with a mature height of 30 to 50 feet, 5-6 feet from pavement,
3. trees with a mature height of greater than 50 feet, at least 8 feet from pavement.

With a distance between your foundation and the trunk of the tree of 27 ft., and the expected height of the ash tree of 40 ft., which would only require a 5 to 6 ft. distance, it would appear your foundation is safe, even if your roof is not. If you still wish to consider installing some sort of root barrier between the tree and the foundation, here is more information about root barriers.

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Arizona Ash Trees

The Arizona Ash tree, also known as Fraxinus velutina is a popular choice in the area because they can adapt well with the hot sunny environment. Because of this, there are a wide variety of ash trees commonly found throughout Arizona. There are more than 65 ash tree species, which can be found on Wikipedia listed in accordance with the region they are located. However, not all woody plants containing ‘ash’ are an actual ash tree, for example the prickly ash and mountain ash are not from genus Fraxinus (meaning, not a real ash tree).

Types Of Arizona Ash Trees

The following lists just some varieties of ash trees found in Arizona:

  • Chichuahua ash – Fraxinus papillosa
  • Goodding ash – Fraxinus gooddingii
  • Fragrant ash – Fraxinus cuspidate
  • Singleleaf ash – Fraxinus anomala
  • Littleleaf ash – Fraxinus greggii
  • Arizona ash – Fraxinus vulutina (also referred to as ‘modesto ash’ and ‘velvet ash’.
  • Shamel as – Fraxinus uhdei (also referred to as ‘tropical ash’)
  • Fantex ash – Fraxinus velutina (also referred to as ‘Rio Grande ash’)
  • Green ash – Fraxinus pennsylvanica (also referred to as ‘water ash’ or ‘swamp ash’)
  • Raywood ash – Fraxinus oxycarpa

There are various positive features about the Arizona ash tree, but all things have a downside. The ash tree was labeled by Horticulturist Calvin R. Finch, Ph.D. as being ‘trash trees’ due to them being partly messy and only having a lifespan up to 30 years.

The Arizona ash tree sheds leaves after the growing season is over, making them deciduous. Of course, many tree varieties are considered to be a messy tree, but the positive side is that the majority of ash trees only shed leaves for a couple weeks. Additionally, the majority of ash tree varieties will produce seedlings one time per year (in large amounts), or throughout the year. This all depends on the gender of the tree, and which species it is. When it comes to having an ash tree, and you want your landscape looking clean you will need to rake on occasion.

Most ash trees grow very quickly, which is great for adding shade. However, this also has its downsides. The quicker trees grow, the more likely they are to have surface roots. Ash tree roots commonly grow near the surface anyway, but are more tolerant against rocky soil and alkaline. Watson and Gilman described green ash trees in a Fact Sheet, reporting the surface roots may “lift sidewalks, curbs, and be a nuisance when mowing”. Meanwhile, Finch quickly indicated the quick growth creates another downside, common with ash trees, “Unless they are pruned regularly, they can quickly grow into a tangled mess causing branch dieback.” You should prepare to have ash trees trimmed every few years, which promotes healthy canopy and branch structure growth.

If ash trees are not trimmed, it can lead to branches being weak and breaking when multiple trunks gather too close. This creates a hazard from structural failure. The best approach is to establish a single ‘central trunk’ during the tree’s youth. Prior to planting your new ash tree, you want to ensure the yard will be large enough to old it as well. Depending on the variety of ash tree, they can range from 40ft to 50ft when mature, with some reaching over 80ft high. All ash trees will provide a round, full canopy with great shade.

Similar to other plants, Arizona ash trees are also vulnerable to different types of disease and pests. These include different fungal infections, mildews, rust disease, leaf scorch, and many types of pests from carpenter worms and webworms to mites and borers. The Verticillium wilt is especially harmful as it is soil-borne fungus. There are regions around the country, especially in the Midwest, where thousands of ash trees have been killed off by emerald ash borer’s. However, Arizona ash trees have been lucky enough to evade this issue, so far. You can learn more regarding the emerald ash borer at Emerald Ash Borer. When trees have poor environmental conditions, it increases their vulnerability to these type of issues, making it important to maintain the tree’s defense with proper fertilizing and watering.

With your efforts of maintaining Arizona ash trees, it is encouraged that you research the species available, because each one has their own range of unique qualities. Dennis G. Watson and Edward F. Gilman have created a tree fact series including hundreds of tree and shrub species, both being University of Florida professors. This would be a great resource to learn the basic information on certain trees you’re interested in. They are partly provided by the U.S. Department of Agriculture and Forest Service.

If well maintained, ash trees are beautiful and lush. However, when ash trees are not properly cared for they can become a nasty sight, and increases the risk of tree disease and pests. Although there are ash tree varieties which are rather resistant to drought, the majority of them will require regular watering. The best setting would be flood irrigation systems. Therefore, if your landscape is not irrigated, you should use a garden hose to mimic this, and do a deep watering one or twice monthly.

If you are located within Arizona and you desire to have a healthy and great looking ash tree in your yard, you should prepare yourself for the increased water bill each month. You’ll also want to remember to regularly fertilize the ash tree(s), placing mulch down will also help. By applying mulch, you will increase the quality of the soil, as the organic matter will break down over time. However, mulch also assists with retaining the moisture, meaning watering less often.

Although Arizona ash trees are not the simplest tree varieties to care for, they can be well worth the extra work. When properly taken care of, ash trees will provide amazing shade, and enhance the overall landscape.

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Arizona Ash Tree

Arizona Ash is a fantastic desert shade tree and has an enjoyable shape and a (relatively) cool shade in summer. However, it grows to become a large tree and if you have an aversion to picking leaves in the fall, it might not be the best tree for you. The male and female flowers are on different trees. The male flowers drop in the spring in large quantities, that can be composted rapidly. The female drops large quantities of one-winged seeds (samara), providing you with a continuous source of seedlings. Scientific name: Fraxinus velutina
Family: Oleaceae, Olive Family

Description: A fast-growing perennial deciduous shade tree native to Arizona & parts of Southwestern New Mexico. The “velvet” is a gray fuzz that covers the young twigs and leaves. Young trees are pyramidal, but the shape becomes more rounded and open as mature height is reached. This is an especially useful shade tree where summers are long, hot, and dry, and where soils are alkaline. It is the species (with its varieties) used most in desert areas, commonly planted as a shade & street tree.

Arizona Ash Leaves

Preferred Habitat: Riparian – river galleries – widely planted ornamental

Leaves: consist of 3-5 narrowly oval leaflets, each about 3 inches long. Foliage turns yellow in autumn.

Flowers: Generally inconspicuous, blooms in spring in clusters. Male and female flowers on separate trees.

Fruit: Fruit in the form of seeds, that hang in dense clusters, will grow on female only if it is near a male tree.

Arizona Ash Bark

Bark: gray, deeply furrowed into broad, scaly ridges.

Elevation: Up to 7000 feet.

Recommended Temperature Zone: sunset: 8-24, 28-30; USDA: 6-10

Frost Tolerance: Hardy to -10° F (-23° C)

Heat Tolerance: Excellent

Sun Exposure: Full sun

Origin: Southwestern USA (Arizona, California, Nevada, New Mexico, Texas, Utah) and northern Mexico

Arizona Ash Male Seeds

Growth Habits: Deciduous tree, up to 30 feet tall (10 m) or more

Watering Needs: Moderate water

Propagation: Seeds

Arizona Ash Female Seeds

Arizona Ash

Fraxinus velutina

  • Other common names include Velvet Ash, Modesto Ash
  • Attractive velvety, gray-green leaves
  • Deciduous shade tree
  • Fast growth rate
  • Cold hardy and heat resistant

Arizona Ash trees, Fraxinus velutina, are deciduous so that they can let the warmth of the sun in during the winter and cast a wide umbrella of shade just in time for the summer! Native to southwestern U.S. and Mexico, these seedless trees are a favorite in a wide range of landscapes from residential, to commercial and lawn applications. They also have a fast growth rate so that you can enjoy the look of a big tree in no time at all! Of course, you can always visit our nurseries and see a big Arizona Ash tree for sale that is ready to thrive and bring all the benefits that a mature tree can add to your yard! We have them available at the size you want!\

An Arizona Ash thrives in a location with full sun exposure. These popular shade trees are cold hardy and heat resistance so that they will look lush and beautiful even in adverse conditions! A perfect tree for the Southwest, once established they are drought resistant with little to moderate water requirements.\

We like to plant Arizona Ash trees as a street tree, and when they are full of leaves they are a magnificent shade tree too! Moon Valley Nurseries value engineers all of our products so that you get the best-quality trees at the best price! If you want big trees so that you can have an instant landscape, you will love our selection. We are the growers so that we can assure their quality is the best you will find anywhere! Visit any of our nurseries today and handpick the perfect Arizona Ash trees for the perfect spot in your yard!\

What Is Arizona Ash – How To Grow An Arizona Ash Tree

What is Arizona ash? This classy-looking tree is also known by a number of alternate names, including desert ash, smooth ash, leatherleaf ash, velvet ash and Fresno ash. Arizona ash, found in the southwestern United States and some areas of Mexico, is suitable for growing in USDA plant hardiness zones 7 through 11. Read on to learn about growing Arizona ash trees.

Arizona ash (Fraximus velutina) is an upright, stately tree with a rounded canopy of deep green leaves. It is relatively short-lived, but may survive 50 years with proper care. Arizona ash reaches heights of 40 to 50 feet (12-15 m.) and widths of 30 to 40 feet (9-12 m.).

Young Arizona ash trees display smooth, light gray bark that turns rougher, darker, and more textural as the tree matures. This deciduous tree provides great shade in summer, with bright golden yellow leaves in fall or early winter depending on the location.

How to Grow an Arizona Ash

Water young trees frequently. Thereafter, Arizona ash is relatively drought tolerant, but performs best with regular water during hot, dry weather. Ordinary soil is fine. A layer of mulch will keep the soil moist, moderate soil temperature and keep weeds in check. Don’t allow mulch to mound against the trunk, as it may encourage rodents to chew on the bark.

Arizona ash needs full sunlight; however, it can be sensitive to extreme desert heat and needs a full canopy to provide shade. The trees rarely need to be pruned, but it’s a good idea to consult a professional if you think that pruning is necessary. If the canopy is too thin, Arizona ash is prone to sunscald.

Part of your Arizona ash care will include feeding the tree once every year using a slow-release dry fertilizer, preferably in autumn.

Arizona ash is prone to fungal disease in warm, humid weather. The fungus damages small, new leaves and can actually defoliate a tree in spring. However, it isn’t deadly and the tree will generally rebound the following year.

One of the more common trees in Arizona are the Arizona ash trees (Fraxinus velutina) because of being able to adapt well with the sunny climate in the area. There are various types of ash trees growing around Arizona, more than 65 species throughout the state. This post on Arizona Ash Tree diseases & care will help you understand the challenges of owning these trees and give tips on how to care for them.

Ash Tree Species

Many of the ash tree species are listed on Wikipedia based on the region they can be located. Although, there are other woody plants which have “ash” in the name too. For instance, the prickly ash and mountain ash. These are not the same (genus fraxinus). The following list provides some of the common Arizona ash tree species, but this is only some of them.

  • Raywood ash – Fraxinus oxycarpa
  • Green ash – Fraxinus pennsylvanca (aka. ‘water ash’ or ‘swamp ash’)
  • Fantex ash – Fraxinus velutina (aka. ‘Rio Grande ash’)
  • Shamel ash – Fraxinus uhdei (aka. ‘tropical ash’)
  • Arizona ash – Fraxinus velutina (aka. ‘modesto ash’ or ‘velvet ash’)
  • Littleleaf ash – Fraxinus greggii
  • Goodding ash – Fraxinus gooddingii
  • Singleleaf ash – Fraxinus anomala
  • Chihuahua ash – Fraxinus papillosa
  • Fragrant ash – Fraxinus cuspidate

Ash Tree Characteristics

There are various positive features about the Arizona ash tree, but they also have downsides. The Arizona ash tree was labeled by Horticulturist Calvin R. Finch, PH.D as being ‘trash tree’ due to their life span only being about 30 years, along with other things.

The ash tree is a deciduous tree, meaning they will shed leaves when the growing season is over. There are many tree types that are referred to as being messy, and the ash tree is one of them. However, the majority of ash trees drop tehri leaves within about 2 weeks, limiting the messy period. They generally produce seedlings throughout the entire year or once a year depending on species, but often in large numbers. When you have ash trees and want a clean yard, you will be raking on occasion.

Most ash tree species will grow quickly, which results in having fast shaded areas, but this also has downsides. When trees grow quickly, it often results in surface roots. Ash tree roots tend to grow near the surface, they can be tolerant to rocky soils and alkaline soils. Although, Watson and Gilman described green ash trees within their Fact Sheet stating surface roots “may become annoying as they can lift sidewalks, curbs, and make mowing a challenge.” Finch added that the majority of ash trees “require regular pruning to avoid them becoming a tangled mess with frequent branch dieback.” Basically, you should expect to require trimming ever few years to keep ash tree’s healthy with a good branch structure. If trimming is ignored, it can cause weak growth and breakage. This is bad for multiple tree trunks, because they will eventually fall and could cause damage. Instead, establishing a single central trunk during the tree’s youth is best.

Prior to planting your new ash tree, there are things to consider. First, you want to ensure your yard is large enough to contain it, because ash trees grow quick, and large. The majority of ash trees mature at 40ft to 50ft, but there are species that get over 80ft high, and they all have round, full canopy’s.

Arizona Ash Tree Disease

Like various plants, the Arizona ash tree is open to many pests and diseases, including mildew, cankering, and different fungal infections. There are other problems that can occur, such as rust diseases, leaf scorch, webworms, mites, borers, and carpenter worms. The ash tree is particularly vulnerable when it comes to Verticillium wilt, a soil born fungus. There are regions through the country (mainly Midwest) which have emerald ash borer’s which have killed ash trees in the tens of thousands. Fortunately, they have not yet affected the varieties of Arizona ash trees. The tree varieties which endure a poor environmental condition have a higher vulnerability to problems like these, making it significant to ensure fertilizing and watering are done adequately to keep the tree’s defense up.

Ash Tree Maintenance

When ash tress is well maintained, they can provide a beautiful and lush addition to your Arizona landscape. However, if you allow your ash trees to go without proper care and maintenance, they can end up being an eyesore and a poor element in your landscape. It can also be the nesting grounds for unwanted pests, and tree diseases. This is why it’s important to ensure proper care. There are ash tree species which have a slight drought resistance, but the majority of ash tree varieties will require plenty of water. To create the best setting for ash trees, a flood irrigation should in installed. Landscapes without an irrigation, flood irrigation should be mimicked using a garden hose for a deep soak one or two times a month.

If you’re living with an ash tree in Arizona, you will want to keep it healthy, so it has a nice appearance. Although, you should be ready to have an increased water bill. In addition, you may desire fertilizing the ash tree often. There are two benefits to mulching your ash trees. First, it enriches the soil as organic matter is broken down. Second, the mulch retains moisture from the watering to maintain wet soil for longer periods.

Although ash trees are not particularly simple to care for, having a healthy ash tree is worth the effort. When well cared for an Arizona ash tree provides great shade, and they are sure to improve your landscape.

Phoenix Valley Ash Trees for Sale

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Plant Database

Wasowski, Sally and Andy

Arizona Ash, Velvet Ash, Desert Ash, Leatherleaf Ash, Smooth Ash, Modesto Ash, Toumey Ash, Standley Ash

Synonym(s): Fraxinus pennsylvanica ssp. velutina, Fraxinus velutina var. coriacea, Fraxinus velutina var. glabra, Fraxinus velutina var. toumeyi

USDA Native Status: L48 (N)

This ash is a small to medium-sized, deciduous shade tree, usually no taller than 40 ft. in cultivation. Tree with open, rounded crown of spreading branches and leaflets quite variable in shape and hairiness. Spreading branches form a rounded crown. Bark is deeply furrowing into ridges. Pinnately compound foliage turns yellow in fall.

This variable species is the common ash in the Southwest, where it is planted as a shade and street tree. It is hardy in alkaline soils and fast-growing. In the desert, ash trees indicate a permanent underground water supply. The leaflets of different shapes are often covered with velvety hairs beneath, as the scientific and common names imply, but also may be hairless. Modesto Ash is a rapidly growing, cultivated variety, widely planted as a street tree in dry areas (including alkaline soils) in California and the Southwest.

From the Image Gallery

Plant Characteristics

Duration: Perennial
Habit: Tree
Leaf: Green
Size Class: 36-72 ft.

Bloom Information

Bloom Color: Yellow
Bloom Time: Apr , May


USA: AZ , CA , NM , NV , TX , UT
Native Distribution: Southern California, s.w. UT & s. NV, east to New Mexico and w. TX, south to Jalisco in central Mexico

Native Habitat: Desert & chaparral streambanks & canyons

Growing Conditions

Water Use: Low
Light Requirement: Sun
Soil Moisture: Dry
CaCO3 Tolerance: None
Soil Description: Rocky soils.
Conditions Comments: F. velutina is an extremely variable species. F. velutina var. coriacea grows in CA; F. velutina var. glabra grows in TX. All varieties are fast-growing and relatively short-lived.


Description: Seeds may be sown outdoors after collection or stored and stratified then sown in spring.
Seed Treatment: Stratify in moist sand or perlite for 30-60 days at 41 degrees.
Commercially Avail: yes

National Wetland Indicator Status


This information is derived from the U.S. Army Corps of Engineers National Wetland Plant List, Version 3.1 (Lichvar, R.W. 2013. The National Wetland Plant List: 2013 wetland ratings. Phytoneuron 2013-49: 1-241).Click herefor map of regions.

From the National Organizations Directory

According to the species list provided by Affiliate Organizations, this plant is on display at the following locations:
Lady Bird Johnson Wildflower Center – Austin, TX
Santa Barbara Botanic Garden – Santa Barbara, CA
Texas Parks and Wildlife Department – Austin, TX

Herbarium Specimen(s)

NPSOT 0334 Collected May 22, 1987 in Bexar County by Harry Cliffe


Bibref 298 – Field Guide to Texas Trees (1999) Simpson, B.J.
Bibref 841 – Native Alternatives to Invasive Plants (2006) Burrell, C. C.
Search More Titles in Bibliography

Additional resources

USDA: Find Fraxinus velutina in USDA Plants
FNA: Find Fraxinus velutina in the Flora of North America (if available)
Google: Search Google for Fraxinus velutina


Record Modified: 2015-11-12
Research By: TWC Staff

Go back

Bob Morris The Internet has all sorts of homemade remedies recommended to control insects. The problem is they have no documented history of working. Bob Morris The dying branches may be a sign of ash decline.

Q: My Arizona ash tree is about 20 years old. Six or eight limbs have dried up and died within the last couple of weeks. Can you tell me the cause of this and what I can do to prevent more from drying up?

A: First, my heart goes out to everyone who was impacted by that horrific event near Mandalay Bay. Let’s hope and pray that it does not happen again.

Judging from your description, most likely your tree has a disease called ash decline. It is important to know the scientific or Latin name of this tree, Fraxinus velutina, because it is called by many names in nursery trades including velvet ash, smooth ash and desert ash, among others. I would not select another ash tree as a replacement.

About four or five years ago I stopped recommending the planting of Arizona ash or Modesto ash in the Las Vegas Valley. Arizona ash also includes Raywood and Fan-Tex ash, which are types or cultivars of Arizona ash.

I would be leery of ash trees labeled as “Bonita” and “Fan-West” because they have Arizona ash genetics in them, but they are too new in the landscape industry to make recommendations for or against planting them.

I personally believe if these trees are getting adequate water, not too often and not too little, and you see this problem, then assume it is ash decline and remove them as soon as possible. We don’t know how this disease spreads so get rid of them and not plant another until we can figure out how to stop it. I am concerned it might be spread by insects such as cicada.

Look for suitable replacement trees. If replacement trees are planted in a rock or desert landscape, then replace it with a desert landscape tree that provides the same benefits. To my knowledge, this disease is not present in the soil, so replacement trees should be fine if planted in the same spot.

Q: Can you tell from the pictures what is wrong with my grass? The dead grass removes easily without a tug, and some of the green grass near the dead grass can also be removed easily like there are no roots. Once it got cooler, the problem has not gotten worse.

A: Thank you for sending such good pictures. I will repost them on my blog. It helped me a lot in this particular case.

Your description made me think it was an insect problem because there were no roots attached. However, once grass dies, the stems rot and all dead grass pulls up easily and without roots attached.

There could be more than one problem going on. Include insects as a possible problem when living, green grass growing on the edges of the brown or dead grass has no roots when pulled up.

In your pictures, the dead or dying areas are semicircular or nearly circular around a green grass center. That is very telling. It is easier to spot this circular or semicircular pattern in grasses that are mown below ½ inch. It’s harder to see it in taller grasses.

This problem is most likely a turfgrass disease called “frogeye,” usually associated with the Fusarium complex of diseases. This disease likes warm to hot weather and very moist conditions.

Other grass diseases like cooler weather, and we don’t see them during hot weather. Still other diseases like moisture but not too much of it. Different diseases, different environments. This disease likes it hot and wet

What to do? First, know when to look for this disease. Because it likes hot, humid or moist environments, look for it during the summer months and when the monsoon season is approaching. You won’t see it during cooler times of the year.

Avoid watering at night. Just before sunrise or when the sun is up is fine but not while the lawn is sleeping. The problem is worsened if the turfgrass or lawn is stressed for some reason during hot weather. Avoid drought stress of the lawn during hot, summer months.

This disease likes to attack areas of the lawn growing in swampy soils or soils that drain poorly. Punch holes in the lawn and soil with a core aerifier during the months just before hot weather. A hand device can be bought, or a gasoline-driven machine can be rented for this purpose.

Don’t mow with a dirty mower. Clean and wash the blade and bottom of the deck of the mower after the lawn is mowed. Mow the lawn shorter during the summer months but never below 1½ inches.

Fertilize the lawn three to four times during the year. Apply a fungicide that is labeled for the disease frogeye or Fusarium when damage to the lawn is first seen during hot summer months. Follow label directions.

Q: I have not been able to get the leaf-footed plant bugs under control on my almond, pistachio and pomegranate trees. The nuts turn black inside. When the almonds first formed and were still soft, I could see sap oozing where the bugs pierced the fruit. I have been spraying with pyrethrin until the weather got too warm. Someone recommended using diatomaceous earth on them.

A: If you search the Internet, you will see all sorts of homemade remedies recommended by different people. These include diatomaceous earth, repelling them with garlic or hot pepper sprays, and even oils of mint and rosemary. The problem is they have no documented history of working.

Until we have some definitive answers about what is working and not working and still safe enough for food crops, we are left with either trying products recommended on the Internet in a trial-by-error method or using products with a known history of success.

I frequently look at the University of California integrated pest management recommendations for insect control. It publishes information that works but, unfortunately, many of the so-called organic methods have not been tested adequately.

Pyrethrin sprays come from organic sources, and some sources are manufactured. Read the label. The label makes this distinction.

There are synthetic pyrethrins, some called pyrethroids, labeled for controlling this insect pest on pistachios. They do work if the directions on the label are followed. Synthetic pyrethrins are designed by chemists to mimic natural pyrethrin’s toxicity. But they are synthetic and may or may not be as safe to use as pyrethrins.

I usually do not promote recommendations found on the Internet that have not been shown to have a history of success. If I do mention something without a history of control, I follow it up by mentioning so.

Bob Morris is a horticulture expert and professor emeritus at the University of Nevada, Las Vegas. Visit his blog at Send questions to [email protected]

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