Many people move here or vacation from other parts of the country and can hardly believe their eyes when they see their first palo verde root borer. I once had one inside a shoe and I thought I was in a horror movie there for a second. These beetles are black, huge, and they can fly. I'm talking about a 3-4 inch long beetle with long antennae besides, big eyeballs, the whole nine yards. Look at a baggie of them that one of our employees found in a valve box the other day:
These beetles spend most of their time underground feasting on the roots of palo verde trees. During the humid monsoon season they typically come out of the ground and you start seeing them. You might see exit holes in the ground around the root zone of your trees, or you may find them in valve boxes like we did. Check your shoes of course… you might find them there too!
How do you know if they are underground on your property?
If you start seeing decline in a palo verde tree, particularly on just one main branch, this is a good indicator. They're munching on the roots below and the water supply to one or more of the branches gets disrupted. You may have a major branch die off. The branch will not recover and needs to be removed.
These palo verde root borers are hard to control because you don't really know they're there. Even if you see signs of damage, you don't know precisely where they are at any point in time. If you want to try to chemically treat them with a pesticide, you wouldn't know where to apply it or if they are even still around. If you see exit holes, they are already gone.
We are fortunate to have relatively few serious plant pest and disease problems here. This is one of them. It's not super common to have them, and even if you do, you might not suffer any tree damage. When I found that one in my shoe, sure enough, it was in the garage about 30 feet from my palo verde tree. My tree never suffered. I never found an exit hole and the branches weren't damaged at all.
Many customers, both residential and commercial, like to have pots as part of their landscape. We can fill them with colorful annuals, blooming shrubs or perennials, agave, cactus, or use them for vegetables and herbs. I have one pot with the same basil plant in it for years. It supplies more than I could possibly eat!
The main challenge with successful pots is the irrigation. It's hardly realistic to water them by hand. We have great intentions and try to keep up with it, but invariably miss a few days here and there and suddenly our plants die.
The surefire way to keep your pots healthy is to irrigate them automatically with a dedicated irrigation valve and timer. If your existing timer can accommodate the extra valve and run times, you can use it. If not, an alternative is to add a valve near the location of the pots and connect them to a simple battery operated timer. These timers are inexpensive and typically allow for many start times.
There's not one exact answer to this question. The factors you need to consider are:
- Are your shrubs on a separate line from your trees? pots? cactus?
- Are your shrubs desert adapted or more tropical varieties?
- What season is it?
- Is your soil clay (slimy when wet), sandy (it doesn't hold water), rocky (lots of gaps for oxygen), or a loamy mixture?
- How much water is delivered to your plant when your irrigation is on (number and size of emitters)?
Xeriscape is a term that comes from a combo of the Greek word "xeros" that means dry and the word landscape. It was coined by a group of employees from Denver's water company. Many cities in Colorado and the Colorado Water Conservation Community have formal programs promoting the philosophies of xeriscape. In the Phoenix area, you'll find landscapers promoting it as well as some cities and even a full fledged Xeriscape Demonstration Garden in Glendale.
To adhere to true xeriscape, you would follow the 7 principles it's based on (as taken directly from the Colorado WaterWise website):
Plan and Design…
for water conservation and beauty from the start.
Create Practical Turf Areas…
of manageable sizes, shapes, and appropriate grasses.
Select Low Water Plants…
and group plants of similar water needs together. Then experiment to determine how much and how often to water the plants.
Use Soil Amendments…
like compost or manure as needed by the site and the type of plants used.
such as woodchips, to reduce evaporation & to keep the soil cool.
with properly designed systems (including hose-end equipment) and by applying the right amount of water at the right time.
Maintain the Landscape Properly…
by mowing, weeding, pruning and fertilizing properly.
Keep in mind, this concept originated in Colorado. To truly apply the seven principles here, they need to be adapted to our local alkaline, rocky, caliche, clay soil, our extremely low humidity, extreme sunlight, heat, and seasonal transitions.
One question that is often asked is whether you should add mulch or compost to the hole when you plant a new tree or shrub. I've read countless professionally created landscape plans that require it, and I've seen many scopes of work for landscape maintenance that call for it too. Most if not all of these scopes were written in another state wherever the property management company's corporate office is and then a search and replace was done and "Arizona" was subbed in for the original state name.
Phooey! Do not add a soil amendment to your planting hole. This is one of the worst things you can do for the health and longevity of your plant or tree. Counter-intuitive right? After all, the pot or box that your plant comes in is filled with a dark mulch soil mixture.
The nurseries are trying to grow the best possible plant in the best conditions, so they use mulch and it must be right, right? Good logic but the end game is opposite for you. They are trying to grow a really good looking plant in a very short amount of time. Longevity is not their goal at all. They want the roots to grow out quickly, and they will do so in such a soft, airy, light soil (less) mix.
What would you think the average life span is of an urban tree in the Phoenix metro area? A number of things come to mind as I debate my guess. A lot of trees in established areas look really big. Some of the eucalyptus are huge. I know the tap root on a mesquite can reach 150 feet deep. This must take a lot of years, so the big mesquites are probably pretty old.
Then I think of all the young trees that pop up in new developments, all the trees that fall down in the wind at a premature age, and the homeowners that don't spend much energy on maintenance. A lot of trees die young as I think about it.
According to Jo Miller of the City of Glendale who cites studies on this very topic - 12 years. Wow!
What are reasons for the short life?
Every summer we get several calls about citrus trees that have issues. Most often the leaves are curled, look a little bleached out, and the customer is concerned that there is a disease or insect to be worried about.
This photo shows tell-tale signs of insufficient water.
The tree is thirsty! The solution: more water.
If your citrus is irrigated on it's own line, separate from shrubs or other trees, add more minutes or likely hours to your timer's run time. If citrus is mixed with other trees, consider adding more time to all the trees, or add more emitters or higher-volume emitters to your citrus tree. Also, be sure that the location of the emitters is out at the drip line of the tree, not close to the trunk. The drip line is that imaginary doughnut circle around the tree that would be formed if water ran off the top of the tree as if it were an umbrella, and dripped onto the ground outside the edge of the leaf canopy.
Thatch is a mat of dead grass material that's made primarily from the stolons of bermuda grass. Stolons are the horizontal stems that vine across and root and cause your bermuda to spread. If you mow your grass infrequently and don't bag your clippings, too many clippings can also contribute to the thatch layer. When mowed at the proper frequency and height, and when using a mulching blade, your clippings are actually beneficial. They break down quickly and help retain moisture for the roots. Over watering and over fertilizing also contribute to excess thatch.
Realistically, eventually most lawns here build up a thatch layer that's counter productive, potentially every year. You have too much thatch when this layer itself is over a half inch thick. How do you tell how thick it is? You can sink a spade shovel into your grass several inches, pull it back out, then do it again in a spot a couple inches away. Create a wedge of dirt you can pull out and look at. Once you have a good look at the cross section, you'll see the dividing line between the green grass shoots, the brown layer of thatch, and the soil. If the thatch layer is half inch thick, consider getting rid of it.
Why is thick thatch bad? Seems like it would be a good insulator.