Wednesday, July 6, 2016

Plant Dessication is a Summer Hazard

Outdoor plants must thread their way through many hazards during the hot months of summer in order to survive, but perhaps the most common, and most deadly, is simple dehydration. 

Plants, as well as animals, must maintain vital levels of water within their systems to sustain life functions.  Both desert adapted and imported plants will benefit from the addition of water although different species, according to how well they are adapted to desert environmental conditions, will require differing amounts of the life-giving fluid.  Since excesses can be just as damaging to plants as deficiencies, proper irrigation becomes a top priority for desert gardeners at this time of the year.

Plants require water for several purposes.  First, it is important to always remember that all living things, plants as well as animals, are largely composed of water.  If water levels become deficient in living plant tissues, plant vitality will be, at best, diminished.  In our busy world, it is easy to forget to turn on the faucet or properly adjust the timer in time to prevent serious injury to plants.  Because of this, many plants suffer serious summer water stress damage.

Second, plants require water for cooling.  The process of transpiration allows the plant to absorb water from the soil through the roots and transport it to other parts of the plant through special water conducting tissues.  Some of the water reaching the leaves eventually evaporates and drifts out through tiny holes, called pores, into the outer atmosphere.  This process of evaporation and diffusion cools the plant.  Water deficient plants will have a warm feel to the leaves while non-deficient plants will feel cool to the touch. 

Third, water is essential for proper plant nutrition.  If root absorption and transport of water and nutrients doesn’t keep pace with the demands and consumption of the plant, the plants begin to heat up, wilt, and starve.  Water is the medium that transports the nutrients from the roots to the leaves where most of the nutrients are used in the process of growth and in the formation of seeds.

The most common symptom of dehydration in Pinal County is leaf dessication, or wilting or drying.  Symptoms include browning, blackening, and sometimes bleaching of leaf tissue that gradually progresses from the tips and edges to between the veins of affected leaves.  In most cases, little can be done to improve the appearance of these tissues once damage has occurred.  However, new damage can be prevented by maintaining good soil moisture and fertility in the future. 

Most trees and shrubs will endure moderate amounts of leaf desiccation before they begin to show symptoms, although unseen damage in the form of loss of plant vigor and vitality can occur. Generally a light fertilization followed by deep watering will restore plant vigor.

Leaf wilting or drying usually appears first on inadequately-rooted or marginally-adapted plants. 
Shallow or limited rooting is very common in many landscapes and plants with this problem will show dessication symptoms quickly.  The quick onset of these symptoms can be noticeably worsened by the hot, dry winds of summer. 

Shallow-rooted trees such as the cottonwood and the mulberry, tender-leaved species such as the silk oak and the ash, and marginally adapted plants such as the rose are among the first to show dessication symptoms.  Plants sitting on dry, compacted, salty, infertile, or chemically toxic soil are also often affected.  Root-binding and caliche layers are other factors that can enhance these problems.  Mature, older leaves usually show the symptoms first because of their longer exposure and because plants give nutrient priority to new growth.

When correcting plant dehydration, it is important not to go overboard.  Over-watering can be just as hazardous as under watering.  The most common disease problem caused by over watering is root rot caused by the water mold root rot fungi.  Most of the water mold root rot fungi, like Pythium, Phytophthora and Rhizoctinia, do not work as fast as their first cousin,  Texas or cotton root rot, but all can be devastating to plants.  These fungal diseases can occur at any time in any season, although they are most commonly seen during the warm summer months.  In moist soil environments, the disease organism proliferates and quickly engulfs the roots of susceptible plants.  Many types of plants can be affected and death can occur within days of initial infection.

Root rot can, in most cases, be prevented by proper watering techniques.  Do not water on a set schedule year round because plants require less water during the cool months than they do during the warm months.  Watering at a summer rate in the winter will give the plant too much water than can lead to disease.  Watering plants in the summer at a winter rate can quickly lead to dehydration.  It is important to change the length of time that an irrigation period will run, and the number of times each week that water is applied, as the seasons change. 

Varying the irrigation schedule so that plants get more water in the heat of the summer and less water in the cool of winter will go a long ways in preventing disease problems.  For the same reason, it is also important to know the soil moisture conditions around trees and shrubs before the next irrigation is applied.  If the soil is still wet when the next irrigation is made, disease may occur.  Check the soil with a soil auger, shovel, or screwdriver to a depth of six inches and feel the soil with a hand to judge the amount of water in the soil.  If the soil is still moist, hold off watering.  If it is dry, give the plant a deep watering sufficient to fill the entire rooting zone and to leach out harmful salts.

Summer survival of landscape plants is a real concern in southern Arizona and Pinal County.  Plants can suffer from drying winds, scorching heat, and the burning sun in the same way that animals and people do.  Many of the plants that are grown in area landscapes have limited tolerance to hot weather conditions and these will take more care when compared with the less demanding desert adapted species.  As we provide for our own endurance and comfort, let’s not neglect our plants.

Friday, June 10, 2016

Water Harvesting

Clouds building over the Mogollon Rim and storms along the Sierra Madre indicate that the monsoon rains will soon arrive and now is the time to make sure that you are ready to capture, store and use storm water to irrigate garden and landscape plants.

Water harvesting it is called, and in the desert, water is such a precious resource that those who live here are always looking for good ways to make every drop count.

Each year during the winter wet season and the summer monsoon, many gallons of water fall onto hard surfaces like roofs, carport driveways and patios.  A water catchment system to harvest this often wasted water is a good way to save money on the water bill.  It is also helps us be good stewards of a very precious resource.

For centuries, people have struggled to survive in water-scarce environments. In so doing, unique systems have been devised to manage those limited water resources. One strategy has been to capture and concentrate rainfall to irrigate crops or to supply water for people and animals. This practice, known as water harvesting, offers some excellent possibilities for the home landscape.

The most important component of a rainfall harvesting system is rain.  Desert environments are always short of this precious commodity and the drought cycles make it even more difficult.  However, every little bit that can be captured can help keep plants healthy. 

In Arizona, water harvesting for crop production is best suited in areas that receive more than 10 inches of rain annually and where summer temperatures do not exceed 100 degrees F. In Pinal County, annual rainfall averages between 8 and 12 inches annually, starting from the west side of the county and working east. Casa Grande averages 8.2 inches a year, Florence 9.8, and the San Pedro Valley between 10 and 12 depending upon the elevation.

Temperature is important to consider because evaporation is directly tied to how hot it gets during the day.  The hotter the day, the faster water will evaporate from a surface.  Closed storage systems help prevent evaporation losses while the water is being kept for future use. 

The other major component of a water harvesting system is a series of hard surfaces coupled with a delivery system to bring the water to the root zones of landscape plants.  In higher rainfall areas, the storage facility becomes even more important as it accumulates and protects the excess harvested water.

Water harvesting systems capture water in three principal ways. These are described as water-spreading systems, diversion/terrace systems, and micro catchment systems. The first two probably do not have application in an urban setting as they involve diverting water from desert washes and applying it to cropping areas. The early cultures of Arizona were masters at these techniques and used them to good advantage.

Residential water harvesting systems utilize variations of the micro catchment system. The amount of water that can be collected depends upon the amount of rainfall received and the square footage of the catchment surface.   There are many factors to be considered, including the influence of wind on how the rain falls and the pitch of a roof but a good rule of thumb is to expect about 0.623 gallons of water per square foot of hard surface during a one inch rain.

Using this conversion factor, a flat roof 1000 feet square could collect 623 gallons of rain water during a rainfall event of one inch.  This would be enough to irrigate a line of plants along a well prepared drainage channel in a desert landscape.  If a drip irrigation system with a good filter and a gravity pressure system were  available, it could irrigate a larger area.

A typical residential water harvesting system uses several different types of hard surfaces to collect or channel rainwater.  Rooftops, garage roofs, driveways and carports, sidewalks, tennis courts or other play surfaces and the ground surface itself can all be used. 

Rainfall that is captured from rooftops can be concentrated with eave gutters and down spouts before being diverted to garden or storage areas.  If the storage tank is at a high point on the property, a manual outlet valve could be opened to drain water by gravity flow but, if this is not possible a small sump pump will help deliver water to where it is needed.

Another benefit of roof top water harvesting is the cleanliness of the water.  Roofs are usually fairly free of sand and other debris that could clog emitters in drip irrigation systems.  The water coming from the roof should be checked, however, to make sure that it has not picked up anything that could damage the system.  If so, the water will probably require just a minimum of filtering before it is used.

Surfaces at ground level can be constructed in such a way that water can be directed to appropriate locations within the landscape, such as the beginning of a water channel or to the wells around trees and shrubs.  The complexity of the system will be directed by the terrain and type of plants in the landscape.

Land surfaces can be shaped and contoured to encourage runoff during rainstorms.  If the planting is some distance from the collection area, planning and careful engineering can take the captured water to the desired location.

Micro catchment systems offer excellent possibilities to the home gardener and variations allow a diverse range of applications depending upon the particular need of the location. Water catchment can be as simple or as complicated as the landscape requires but good planning will always be a key to success when installing these systems.

Effective water harvesting concentrates rainwater runoff for use in irrigating landscape plants.  Not only are they fun projects to occupy part of our gardening time but, once in place, we get the added benefit of seeing our landscape plants get watered automatically while we sit in our easy chairs and watch it rain.

Monday, May 23, 2016

Beneficial Insects

Before you mash, repel, or spray those insects in your garden, make sure that they are not “beneficial,” that is, one of the “good guys.”

There are a great many insects that fight on our side against destructive insect pests. These allies and partners of the insect wars are called “beneficial insects.”  Many times it is only through their assistance that the tide of battle turns our way. 

Consider aphids, for example.  In the spring and early summer, and sometimes again in the fall, populations of soft-bodied, sucking mouthpart aphids can explode quickly when conditions are right for their growth. Caught in time, most aphid problems can be averted by washing the plants with a strong stream of water, applying insecticidal soap, and letting the beneficial insects clean up any escapees.  Sometimes the beneficial insects will get there even before you do. 

Beneficial insects work in two different ways.  Predators feed on the insect itself, and parasites generally lay their eggs on the host so that their young can feed.

Since predators feed outright on the bodies of insects, they generally are generally as large or  larger than their prey so that they can compete in the battle royal that usually occurs between them.  Mobile bad guys, insects that can easily move about, usually do not go down without a fight.  Lady beetles, lacewing larvae, and assassin bugs are examples of predator insects.

The ladybeetle is one of the best known of the predator insects.  These rounded beetles come in many sizes and colors.  The most common species found in Arizona is the convergent ladybeetle, named for the two converging white stripes behind the head.  The beetles are brightly colored with red front wings speckled with black markings.  The adults lay orange egg clusters on plants near groups of aphids.  The eggs hatch into tiny black and orange larvae which feed on aphids in great numbers.  As the larvae grow, they resemble tiny beaded dragons.  Once they reach maturity, they form a rounded black and orange-marked pupa attached to the plant.  Pupae are often mistaken for bird droppings.

The lacewing is another outstanding predator insect.  Adult lacewings are delicate, pale green or light brown insects about one-half to three-fourths of an inch long.  Their wings have many veins, which gives them the netlike or “lace” appearance.  They are attracted to lights at night and may be mistaken for moths except they have a characteristic fluttering flight when disturbed.  The adult stage feeds on flower nectar only and is itself not predatory.

All lacewings lay pale green eggs on the tips of threadlike stalks on the underside of leaves.  The immature lacewings hatch within a few days.  They are no longer than one-eighth inch and are light brown in color.  Their shape resembles that of an  alligator and have large, sickle-shaped mandibles with which they suck the juices from insect eggs and small prey.  They are ferocious feeders, and consume large numbers of aphids, other insect pests, and insect eggs of all kinds.  When the larvae mature they form a yellow silken cocoon in which to pupate. 

The praying mantis is also a well known predator insect.  It sits and waits on plants until another insect crosses its path, and then it captures its victim with its spiny front legs.  Praying mantis females lay their eggs in 1 to 2 inch long “cases” made of a dark brownish-gray papery material with numerous compartments.  The egg cases are glued to twigs or branches, and are commonly found attached to the underside of boards.  Praying mantis young emerge from the cases in the spring.  They look like miniature adults. 

Other predators include assassin bugs and ambush bugs whose names pretty much describe their predatory activities.  There are also damsel bugs, big-eyed bugs, minute pirate bugs, syrphid flies, wasps, and dragonflies.  Altogether, they form a formidable line of defense for garden and landscape plants and work in our favor to help maintain the balance of nature.

Parasitic insects lay their eggs on or within the bodies of their prey, and because of this, they do not need to be, and generally are not, as large as the host insect.  Once the egg of the parasite hatches, it is the larva, or young of the beneficial insect that uses the host insect for food.  Because adult parasite insects are often much smaller and weaker than their prey, they must rely on their agility to provide the edge needed for success.  Parasitic wasps and flies are included in this group of beneficial insects. 

The adult stage of parasitic insects generally lives outside of the host insect but lays the eggs on or within a living host.   After the eggs hatch, it is the young which feed on host tissues until the host is killed.  Immature parasites complete their development in only one host.  Because they are extremely specialized, they often only attack one or a few closely related species of insect.  Parasites of insects do not in any way harm humans or their pets. 

A fascinating example of a parasite is the eucharitid wasp which attacks ants.  This particular wasp lays her eggs on the leaves of trees.  The eggs hatch into mobile immature larvae that are able to crawl about on the leaf surface.  In the spring, worker ants climb into the trees in search of aphids and other insects for food. The parasite larva attaches itself to any worker ant that comes close and hitches a ride back to the nest when the worker ant goes home.  Once in the nest, the parasite drops off and attaches itself to a larval ant.  The wasp larva feeds on the ant larva, eventually killing the ant.  After emergence from the pupa, the adult wasp flies out of the ant nest to lay her eggs on leaves once more.

Other types of parasitic insects control aphids, whiteflies, grasshoppers, beetles, moths, bees and insects.  Even though they are often not seen by the average person, they are definitely there and doing their job.

In the fight for control of the garden, the predator and parasitic beneficial insects are the little known heros of the garden.  Both types destroy many insects every day that would otherwise damage or kill our tender garden plants.  Some work quickly and produce dramatic results; others work so slow that their efforts are rarely recognized in the garden.  Both, however, are critical to maintaining the balance of nature in the plant’s favor.  They deserve our respect, our appreciation, and our protection.

Tuesday, April 12, 2016

Preventing Bird Damage in the Garden

Birds can devastate young vegetable seedlings or ruin fresh fruit in the blink of an eye but if we know what to do, and take action before they strike, we can often prevent problems.

Many of us are all too familiar with damage caused by birds to ripening apricots, plums, grapes, and other garden fruits.  We know it happens and even come to expect it.  However, few people realize that birds can also seriously damage vegetable gardens.  The fact is that yes, birds can make pests of themselves in vegetable gardens, particularly when young plants are in the seedling stage.   Some people would be quick to say that they can be very aggravating pests.  For those who know what I am talking about, I sense your frustration.

Birds can damage fruit and vegetables in two basic ways.  The most obvious is direct feeding and the other is contamination of food products.  Let’s consider some examples.

Horned larks are notorious in the commercial vegetable industry and in home vegetable gardens for nipping at new seedlings emerging from the ground.  They usually don’t really eat the plant.  Mostly  they just bite it, perhaps for a taste of the sap.  Sometimes though, they will pull it completely out of the ground.  In these cases, it is not uncommon to find the poor, abused seedling lying discarded nearby after this not too gentle treatment.  Horned larks are not the only ones that do this of course, but they are notorious for this kind of damage.

Other birds like finches, sparrows, thrashers, and wrens will peck holes in the soft flesh of ripening fruit.  Figs, apricots, peaches, and plums are common targets for birds. Woodpeckers and their relatives the sapsuckers, peck holes in the rinds of citrus fruit looking for a juicy taste of fresh fruit.  Many birds figure out how to hunt the seeds that you just put in the ground and have lunch at your expense. If you are growing your own grains, watch out for the red-winged blackbird.  They and their cronies will absolutely love your harvest.

Birds also cause damage to garden crops through direct contamination of the edible parts of the plant.  Bird droppings are usually not a problem when they fall on fruits that will be peeled, but when they end up on difficult to wash fruit like blackberries, strawberries, and clusters of table grapes, they make a real mess and the residues could harbor disease.

The sight of bird feces on fresh fruit is guaranteed to quickly destroy any desire one might have to pluck a ripe fruit and plop it directly in the mouth.  Even so, most produce can be cleansed with a careful washing.  In fact, it is a good idea to inspect food materials carefully before you place anything in your mouth.  Even if you can’t see any contamination, it is always good to wash before you eat.  It is better to be safe than sorry, I say.

How do we prevent bird problems in the garden?  When thinking about control, many people quickly jump to the idea of chemical poisons and repellents.  However, since most gardeners do not have the proper training, certification, and license to use chemicals to control birds, that way is out.  Don’t even think about it.  Put it out of your mind.  Don’t go there.

The same goes for shooting with fire arms, sling shots, or arrows.  There are a whole bunch of laws that if violated, could bring embarrassment, financial difficulties, and even imprisonment.  Unless you have legal permission, birds cannot be harmed in any way.  Just so we are clear, almost every bird you see is protected by state and/or federal regulations.  Killing or injuring birds without a license carries a stiff punishment and could get you into big trouble.  Don’t do it.

So, what can you do to protect your garden from the ravages of hungry birds?  There are a number of things that can be done and most fall within three categories: frightening devices, mechanical barriers, and habitat modification.

Okay, let me emphasize right here that I am not recommending the use of loud sounds in populated areas to frighten away birds.  While farmers out in the country might get away with propane cannons, fireworks, and blank shotgun blasts, no one in the city wants to wake up to a loud bang or pop at the crack of dawn.  Not only will the neighbors be upset, but the local law enforcement community also.  They take a dim view of such activities, even if it is in the name of good gardening, because there are laws against disturbing the public peace.

On the other hand, a good predator silhouette works very well to frighten birds away.  It is quiet and causes no harm to the animals.  Some people use hawks or snakes, but I like to use an owl.  Strategically placed and moved regularly, birds have a tough time telling the difference between a real owl and a plastic one in the few seconds they have to make a life or death decision.  I really like the plastic owl that, with power from a solar collector, is able to move its head. Any movement is good because it gives the birds a more realistic view.  I have seen birds literally do a u-turn in mid flight when they suddenly see what they think is a live owl hiding among the foliage of a fig or apricot fig.  Predator images seem to work equally well in vegetable gardens.

Mechanical barriers are another good way to keep birds away from sensitive plants.  Many people already use bird netting over citrus, apricots, grapes, and plums to protect their fruit.  Floating row covers, light spun fabric especially designed for agricultural use, or the netting you use on your fruit trees can be set up to keep birds away from tender vegetable plants until they are large enough that birds lose interest.  The floating row cover can be laid directly on top of the plants because they are light enough that they do not damage plants.  Netting can be laid on top of a pole framework to keep them off the plants.

The last way to prevent bird damage is to change the natural habitat around your garden. Modifying conditions to make the area less interesting to the birds will help prevent bird populations from becoming excessive. The fewer the birds, the less damage will be sustained. 

Of course, birds can travel some distance to a feeding area so habitat modification may have its limits, but anytime we can camouflage or make a feeding site less interesting the better off we will be.  Common modification techniques include removing roosting areas like trees and shrubs in the vicinity of the garden area, moving the bird bath and decorative bird houses to another part of the yard, and eliminating nearby resting areas.

Birds cause many types of damage in the garden.  While there are some things that we definitely should not do, there are steps that you and I can take to effectively prevent bird damage without harming protected species.

If you have questions, you can reach one of the Master Gardeners at the Cooperative Extension office, 820 E. Cottonwood Lane, Building C, in Casa Grande.  The telephone is (520) 836-5221, extension 204.

The University of Arizona is an equal opportunity, affirmative action institution.  The University does not discriminate on the basis of race, color, religion, sex, national origin, age, disability, veteran status, or sexual orientation in its programs and activities.

Rick Gibson
Extension Agent, Agriculture
University of Arizona Cooperative Extension

Monday, March 7, 2016

Working Safely in the Garden or Landscape

While often peaceful, the garden or landscape is not always the safest place to work.        

No one really wants to lose fingers or toes in a lawn mower accident, finish a great day in the garden with a strained back, or spend an afternoon in the emergency room recovering from heat injury.  These are just not fun experiences.  Yet, all too often, a day in the yard ends up with someone in pain.  Safety should be a topic of concern for all who work outdoors.

People find all kinds of ways to hurt themselves.  Lawn mower accidents, dehydration, muscle strains, flying debris injuries, cuts, punctures, and a whole host of other problems can afflict those who work in gardens and landscapes.

According to the National Institute for Occupational Safety and Health (NIOSH), 789 traumatic injury deaths occurred among landscape service workers and their first line supervisors between 2003 and 2006.  While most of these deaths, about 33%, were related to transportation to and from jobs, a good many were due to falls, being struck by falling objects, and electrocutions.  Of those deaths reported, 318, about 40%, occurred around private residences. 

While news of fatalities can be quite sobering, other less serious accidents can significantly impact lives.  A strained back, for example, is still a painful injury and can take its toll on an individual’s overall productivity.  If all it takes is a little training, experience, and vigilant awareness to prevent injury or death, it just makes no sense to ignore safe practices.

The best way to prevent a lot of injuries is to dress correctly for the job.  Properly fitting, long or short-sleeved shirts and long pants prevent injury from the sun as well as from scratches and pokes.  High-top, lace up boots and shoes with traction soles and steel-reinforced toes provide support and protection to feet, and ankles.  Is it really a good idea to run a power mower in sandals, flip-flops, or bare-feet?  All it takes is one mistake and a trip to the emergency room is added to the day’s list of things to do.  Give yourself a break and cover up those feet.

If you use a string trimmer or other high velocity piece of equipment that could fling pebbles, twigs, or other loose material, think about investing in a face shield or goggles to protect your eyes from dust and flying particles.  Yes, this equipment can be a little uncomfortable during the summer heat, but a little temporary heat rash is much better than permanent blindness.

If the conditions are dry and dusty, it is a good idea to use a dust mask or other type of respiratory protection.  I use a mask each time I run the blower over the carport, unless the wind is blowing fast enough to keep the air around my face clear.

If you work around trees outdoors, you may want to purchase a plastic “bump” hat.  A friend of mine once asked me when the tree in his front yard would “grow up” far enough to give him room to mow his lawn without hitting his head on a low branch.  I had to tell him that trees do not grow that way.  I suggested that he either prune back that low hanging branch or invest in head protection.

I rarely work outside without a good pair of gloves.  I like a pair of inexpensive but sturdy leather gloves for almost all jobs.  Mine have a cloth or canvas backing for coolness during the summer, but sturdy leather covering the palms.  A good pair of gloves will protect the hands from cuts, scrapes, chemical or thermal burns, and vibrating equipment.  In the summer, gloves will also offer protection from scorpion stings or spider bites while you are gathering loose litter or other materials.

Before you use any power equipment, read the directions.  The directions will give you suggestions for safe operation of the equipment.  This is especially true of power mowers, string trimmers, and hedging shears.  Many hand tools also offer suggestions for safe use.  It is always in our best interest to learn and follow the recommendations.  I still have a scar on the tip of one finger where I got in a hurry, was working without gloves, and nipped the tip of my finger with a pair of hand operated grass shears.  It frequently reminds me to remember and practice safety rules.

We often work with a variety of lawn or garden chemicals.  Fertilizers, insecticides, weed products, and fuel for power equipment are commonly used by “do-it-yourselfers” as well as professionals.  All chemicals present a variety of hazards and must be used correctly.  The best source of information to correctly mix, use, and store chemicals is the label.  The label is a legal document and will provide key information for safe use.  Gasoline and other combustible fuels should be safely stored and carefully used to prevent burns and toxic reactions from inhalation and ingestion.  If instructions say to use protective clothing and equipment, use them.

 Most outdoor people know the value of getting the chores done early in the summertime.  An early start when the air is still relatively cool will go a long way towards preventing heat injuries and dehydration.  Plan to be out of the yard or in the pool by the time the temperatures near 100 degrees F.   Temperatures over the magic three digit mark will quickly draw the energy right out of you and perhaps lead to heat exhaustion or even worse, heat stroke.  Be sure to drink plenty of water during your work session.  Staying hydrated will help ward off heat injury.

Don’t even get me started on safety violations while pruning trees and shrubs!  Over the years, I have seen a lot of mistakes resulting in some devastating accidents, accidents that could have been avoided by simply following a few basic rules.

A most important rule, and one that is commonly violated, is “use the right tool for the job.”  For example, never use a circular saw for pruning large branches out of a tree.  One slip and the blade hits the leg.  I have heard of too many who made this mistake and have ended up fighting for their lives.  When a hand tool is required for pruning, use a pruning saw and not a woodworking saw.  Pruning saws always cut on the “pull” stroke and not the “push” stroke as a protection from falls and other injuries.  Putting pressure on the pull stroke gives the operator better control and stability on a ladder.  If you must use a chain saw, for crying out loud, know what you are doing.  Watching people work out of balance on a ladder or hanging precariously in a tree with a chain saw strikes terror in my heart. Let’s be safe out there!

No matter what the job, working safely outdoors requires training, experience, and vigilant awareness.  Whether working with power tools, lifting heavy loads, or working in hot weather, we can be safe from injury if we exercise caution and a little common sense.

If you have questions, you can reach one of the Master Gardeners at the Cooperative Extension office, 820 E. Cottonwood Lane, Building C, in Casa Grande.  The telephone is (520) 836-5221, extension 204.  The author’s email address is

The University of Arizona is an equal opportunity, affirmative action institution.  The University does not discriminate on the basis of race, color, religion, sex, national origin, age, disability, veteran status, or sexual orientation in its programs and activities.

Rick Gibson
Extension Agent, Agriculture
University of Arizona

Monday, December 28, 2015

Mistletoe: An Enemy to Plants

Because they have the unique ability to take energy directly from another plant, the various species of mistletoe can cause the slow, steady decline of host trees and shrubs.

Mistletoes are perennial, shrubby, woody or semi-woody flowering plants that attach themselves to other plants and steal water and nutrients from the host plant.  Because they are dependent upon these host plants for nourishment, they are called parasites.  Unlike dodder, which lacks any ability to produce food for itself, the mistletoes do contain the green pigment chlorophyll that allows them to manufacture food from the energy of the sun. 

In the desert Southwest, there are about a dozen different species of mistletoe that affect trees and shrubs.  Each of these species have the ability to invade the living tissue of host plants and extract water and nutrients for their own growth and development.  It is this unceasing loss of strength, coupled with the twisting and distortion of branches caused by the mistletoe that can eventually lead to the decline and sometimes death of trees and shrubs.

The traditional European mistletoe is Viscum album, but in the United States two genera, Arceuthobium and Phoradendron are the representatives of the family.  Arceuthobium species are dwarf mistletoes and are weak, herbaceous plants with leafless yellow-green to orange stems.  These mistletoes parasitize pines and junipers all across the Southwest.

Members of the Phoradendron generally have well-developed leaves on strong, shrubby, almost woody stems.  Some species have large, yellow-green leaves while other species are essentially leafless.  The common desert mistletoe that infests many of the desert legume trees like palo verde, mesquite, and ironwood has only scale-like leaves.  The large-leafed yellow mistletoe is often picked and sold during the holiday season as a way to steal a kiss from someone special.  It is most commonly found on riparian softwood trees like cottonwood, sycamore, willow and ash.

Most mistletoe species produce small white to pinkish or green-tinged berries, whose single hard seeds are surrounded by fleshy, sticky pulp.  The fruit seems irresistible to birds, who then redistribute the seeds to new locations, not only through their droppings, but also by inadvertently carrying the sticky seeds on their beaks and feet.

While otherwise healthy host plants may seem to tolerate one or two mistletoe plants, the parasitic plant’s ability to effectively produce and disperse seeds all but insures the spread of the infestation and the slow decline and even death of the host plant.  The weakening, disfigurement and eventual death of shade, food and lumber producing trees represents a significant worldwide economic loss each year.

Control of parasitic plants is often difficult.  The easiest and most common method of control is to simply prune or break off the plants.  This is best done before flowering to prevent the development and dispersal of seeds.  Removal of the parasites also helps to reduce the drain on the host tree as pruning prevents the loss of valuable water and nutrients from the host. 

Unfortunately, mistletoe pruned in this manner usually does not remove all of the parasitic plant, and the parasite will often grow back quickly.  For this reason, frequent pruning is often necessary.  To prevent frequent regrowth, remove the mistletoe as close to its point of attachment as possible.  Some bark tissue may safely be removed during this process, but try not to cut too deeply, or the branch may snap under its own weight or in a wind.

A more permanent step would be to completely prune away infected limbs and branches up to 12 or more inches below the mistletoe point of attachment. This type of pruning works well for younger clumps of mistletoe, but it cannot be done on older growth mistletoe, or where the mistletoe is on large, often essential limbs.  Be sure to prune the infected limbs back to their point of attachment with a larger branch or the trunk.  Never leave the stub end of a branch that could invite the entry of other diseases and wood-destroying insects.

Where infestations occur on essential branches or on the trunks of trees, some measure of control can be achieved by pruning the offending mistletoe back flush with the tree and then wrapping the exposed points of attachment with dark, light-excluding plastic sheeting.  The lack of light on the remaining parasite tissue will prevent the regrowth of the pest.  As the mistletoe is deprived of sunlight, the parasite will eventually die.  However, this make take a year or two, so it is important to check the plastic wrap regularly and replace it if it begins to degrade.

Mistletoe is a common pest on local landscape trees, but by careful vigilance and proper tree care much of the damage to, and death of, these valuable plants can be avoided.

If you have questions, you can reach one of the Master Gardeners at the Cooperative Extension office, 820 E. Cottonwood Lane, Building C, in Casa Grande.  The telephone is (520) 836-5221, extension 204.

The University of Arizona is an equal opportunity, affirmative action institution.  The University does not discriminate on the basis of race, color, religion, sex, national origin, age, disability, veteran status, or sexual orientation in its programs and activities.

Rick Gibson
Extension Agent, Agriculture
University of Arizona Cooperative Extension
820 E. Cottonwood Lane, Building C
Casa Grande, Arizona 85222
Voice:  (520) 836-5221
Fax:     (520) 836-1750

Date: November 26, 2014

Wednesday, December 16, 2015

Plants Provide Many Benefits In Our Lives

In a hurry up world where life seems to constantly accelerate and the day-to-day challenges appear to bring ever more stress, plants can impart a sense of needed stability and well-being in our lives. 

There are many scientific studies that indicate a strong relationship between healthy people and exposure to plants, both indoor and out.  Here are some examples taken from a series of articles published just in the January-March 2000 edition of  “HortTechnology”, a quarterly journal for horticultural professionals.

The first example comes from one of the earliest studies looking at the beneficial effects of plants.  Patients having a room with a view of trees rather than a view of a brick wall spent almost a day less in the hospital, used fewer doses of strong pain relievers, and received fewer negative comments from hospital staff on their charts.  The study instantly attracted the attention of both the medical community and horticultural researchers.  

In another study, people in an experiment viewed slides of nature scenes with water and vegetation, slides of nature scenes with only vegetation, or slides of urban scenes without vegetation.  When people viewed either of the nature scenes, they exhibited higher alpha brain wave amplitudes than when viewing urban scenes.  

“Okay, Rick, what exactly does that mean?”  Higher alpha brain wave amplitudes are generally associated with lower levels of physiological arousal and higher levels of attentive relaxation.  In other words, those tested were judged to be under less stress.  That is a good thing.  The subjects also reported that the nature slides held their attention better than the urban slides, even though all of the slides were judged to have similar informational content. 
One study focusing on college students showed that those performing tasks that required deep mental concentration performed significantly better on some tests when they enjoyed a window room that opened out onto a nature scene than those who had views of scenes dominated by buildings and sidewalks.  Nature scenes seemed to enhance mental attention and reduce fatigue.

A 1996 study asked apartment complex residents about domestic violence.  Respondents lived in public housing and could not choose their apartments.  Some were assigned to live in complexes surrounded by trees, while others were assigned to buildings without green surroundings.  When asked if they had engaged in violence during the past year, 22% of the women interviewed from the apartments without trees said “yes” while only 13% of the women in the apartments surrounded by trees said “yes”.  When asked if they had hit their children in the past year, 14% from the non-green apartments said “yes”, while only 3% living in apartments near trees said “yes”.   

The list of studies goes on and on, here in the U.S., and around the world.  The evidence is quite clear.  Scenes associated with plants can reduce stress, speed healing, enhance workplace productivity and improve the human outlook on life.   

These results have not gone unnoticed.  Around the world, plants are showing up inside public buildings, in malls, in hospitals, and long term care centers.  School gardens are being planted and cared for.  Community gardens, consumer supported agriculture enterprises, and agricultural tourism operations are flourishing.  Adults working in the court systems assign juvenile offenders to work in community gardens.  Yes, horticultural therapy has become a viable tool in the medical field, but it is also key to well being in our every day lives.  

These real benefits, however, are sometimes masked, covered up, if you will, by the very challenges of life that make our involvement with plants so essential.  The bottom line is that we are becoming too busy to garden, to care for house plants and to plant trees and shrubs.  

If we do install landscapes, we often give in to the temptation to make them so labor-free that we do not find the need to interact with them in any way other than in the most brief of encounters.  This may be helpful in our busy worlds, but it is expensive in terms of the very real benefits that could be ours if we regularly went out among our plants.

So, what can you and I do?  There are several ways to enhance our interaction with plants and to improve the surroundings in which we live.

First, bring plants indoors.  Look around the interior living space and search for locations where an indoor plant might fit.  Identify  locations where light, humidity, and temperature conditions fit the needs of the plant.   For example, do not place a boston fern in an area where the cooler or heater vents would blow on the plant and dry it out.  Ferns like moist, humid areas such as in the shower or bath.  

Group indoor plants into natural appearing arrangements that give a sense of the outdoors from which they came.  Such arrangements help create a peaceful, natural feeling similar to that experienced in native environments.

Second, search for ways to make outdoor landscapes user friendly.  Arrange and install outdoor landscapes with the intent that they will encourage human interaction.  Select plants that fit the specific needs of the landscape and of the people that will use it.  Let the landscape be an extension of the home so that it will be an easy and natural step to exit the home and immerse oneself in the outdoors.  A well designed and maintained landscape will entice people indoors to move outside.

Consider placing benches or chairs in strategic locations that invite a passerby to linger and enjoy the setting.  This may be tucked away between trees or behind shrubs away from busy traffic areas, or it may simply be next to favorite flowering shrubs or garden areas.  Such locations encourage introspection and relaxation from busy schedules.

Third, notice the use of plants and natural environments in public places and recognize them for what they bring to those who visit those areas.  Many malls, for example, spend considerable resources to bring the natural environment inside for a peaceful, if not restful, shopping experience.  Encourage businesses and other establishments that you frequent to consider installing plants into their decor.  Tell them about the potential benefits that could come both to them and their customers from the practice.

Fourth, become active in neighborhood and community beautification committees, school garden projects and community garden efforts and encourage the proper use of landscapes and indoor plants in all areas.  Volunteer time not only lifts those served, but also reaps benefits to those serving.

Finally, become informed about plants and the potential benefits that come from human interaction with plants.  Know how to properly select, install and care for indoor and outdoor plants in our harsh, desert environment.  

Healthy plants in our living environment can help all of us accrue actual emotional, physical and psychological benefits each and every day.  The bottom line is, plants help us live better lives. 

If you have questions, you can reach one of the Master Gardeners at the Cooperative Extension office, 820 E. Cottonwood Lane, Building C, in Casa Grande.  The telephone is (520) 836-5221, extension 204. 

The University of Arizona is an equal opportunity, affirmative action institution.  The University does not discriminate on the basis of race, color, religion, sex, national origin, age, disability, veteran status, or sexual orientation in its programs and activities.

Richard Gibson
Extension Agent, Agriculture
University of Arizona
Pinal County Cooperative Extension Office
College of Agriculture and Life Sciences

820 E Cottonwood Ln, #C
Casa Grande, AZ 85122
Tel: (520) 836-5221 ext. 227
Fax: (520) 836-1750