Basil, cilantro, Italian parsley easy to grow in Las Vegas

Q: What is the best way to grow basil, cilantro and Italian parsley in Las Vegas? I tried growing them in pots and transplanting them to a raised bed. I am not sure if I water them too much or not enough, but the leaves fall out or dry out.

A: All three are easy to grow here if you prepared your soil adequately and grow them at the right time of year. All three handle full sun, but they should not be put into areas of the landscape that are extraordinarily hot because of reflected heat from walls in the late afternoon.

Your basic elements of success, in order, will be planting at the right time, soil preparation, watering correctly, protection from bugs and location in the yard isolating them from cold and wind.

Basil loves the heat and should not be put in the garden until temperatures are warm, perhaps late March or early April. Basil does not like temperatures below 55 degrees and freezes exactly at 32.

Cilantro and Italian parsley prefer cooler temperatures of spring and fall rather than the heat of our desert summer. A great time to plant cilantro and Italian parsley is in the early fall or late summer when temperatures start to cool off.

If you place cilantro and Italian parsley in warm parts of the landscape protected from wind, they probably will survive the winter. When temperatures get cold in late fall and you fear a freeze, throw a light sheet or a crop cover over the top of them just before sundown when soils are still warm. This will protect them 5 to 6 degrees below their freezing point.

Insect problems, generally speaking, include aphids and "worms," which are larva of moths mostly. Organic pest control options include insecticidal soap, oils such as horticultural oil or Neem, Bt or Spinosad and a pyrethrum product for fast knockdown.

Use them in rotation as pests start to appear and as needed when they are growing. Leaf cutter bees can be a problem on basil, but I do not recommend any insecticides. It is better to cover basil with insect netting or ignore their damage to the leaves.

Q: I am having a problem with a worm I sent to you infesting my trees. I haven't identified the pest, but how did this infestation happen and is it common in the Las Vegas Valley? Secondly, how is the cycle of reproduction of this bug?

A: You have the larva or worm of a beetle you dug from the branches of this tree. These larvae, or worms, are called "borers." Notice its flattened head so it is commonly called a flat-headed borer. The adult of this worm is a beetle about ½ inch long.

The adult female beetle flies in search of a mate so that it can lay fertilized eggs. It finds a male by smelling the male's pheromone it releases and flying upwind. Most likely these nuptials happen any time from about April through August. Once the female mates and prepares to lay eggs, she searches for suitable woody plants that are injured or unhealthy.

The female, laden with fertilized eggs, searches for suitable plants through another one of her senses of "smell". One of the "smells" she identifies is plant damage from intense sunlight or sunburn.

She lays her eggs in the general vicinity of the damage but near living plant tissue. The larva hatches from this egg and tunnels inside the plant just under the bark. The wood just under the bark is laden with wet, sugary juices from the plant that the flat-headed borer feeds upon.

As this flat-headed borer feeds, it inches slowly forward just under the bark making a convoluted tunnel. At the beginning of this tunnel is the flattened head, and it leaves a trail of sawdust and feces behind it as it feeds, moves and creates the tunnel.

This borer turns into an adult flying beetle inside the tree, exits and searches for a mate to repeat the life cycle. Sometimes, if it is late in the season, this borer will tunnel into the center of a limb to survive the winter and exit as an adult the following spring.

These borers attack dozens of different trees and shrubs, many in the rose family. This includes many of our fruit trees, landscape plants like pyracantha, loquat, flowering plum and several others.

What to do? Dig it out. Using a sharp and sanitized knife and, laying it almost parallel with the branch, cut away the surface of the branch exposing the tunnels and the worm. Clean up the damaged area so the worm has no place to hide.

Prune it out. If the damage is more than 50 percent of the branch, remove the branch. If removing the branch seems excessive, dig out the worm and give it a chance to heal.

Use an insecticide. In a last-ditch effort to save the tree, use a soil-applied systemic insecticide. Though it might be labeled for fruit trees, use these products on nonflowering ornamentals only. Apply this product just after flowering to minimize problems with bees.

Apply whitewash. Whitewashing the upper surfaces of limbs, scaffold limbs and trunk reduces sunburn, which in turn reduces problems from borers. Make the whitewash by mixing white latex paint 1:1 with water, or buy a commercial whitewash.

Q: I have a hedge of pyracantha on the northeast corner of my property. It grows underneath three large pine trees so it does not get much sun. The soil is mostly just rocks. The plant is thinning and getting bare in the center, but the top is still fairly green. What can I do to make it look better?

A: Without seeing it, I am guessing it is a combination of light as you mentioned, lack of soil improvement, perhaps irrigation, maybe improper pruning and borer problems. To get it to look better, you need to address most, if not all, of these shortcomings.

Removing lower limbs of the pines helps get more light to the plants. The natural response of woody plants or ornamentals to a lack of light is sparse foliage. Unfortunately, sparse foliage may be true for other reasons as well.

Pyracantha is in the rose family and likes soils similar to soils that most of our fruit trees like too. It is susceptible to the same problems as fruit trees in this family, such as peach, apricot, plum and apple. It isn't terribly fond of desert landscapes and rock mulch where it is planted most of the time.

Pyracantha needs a lot of sun, but it is thin-barked so it sunburns easily if its canopy is open. Sunburn leads to borer problems.

An attack of borers would cause the bark to come off of the trunk or major limbs. A light borer attack to the plant can cause no obvious visual damage. There is an insecticide you can apply to the soil that gives the plant season-long control of borers.

Pyracantha hedges nicely, but if it is pruned incorrectly, it will "open up" just as you are describing. Pruning, hopefully, will result in shading the exposed trunk or major branches.

So what to do? Check the irrigation and make sure it's getting enough water and increase the amount if it is not. Increase how much it receives, not how often. Pull rocks away from the plant and put down 3 to 4 inches of compost along with wood chip mulch.

When pruning, be very careful not to open the canopy too much, which might allow the sun to burn the trunk and limbs. Fertilize once a year in the spring with a fertilizer formulated for flowering and fruiting of woody plants. Fruit tree fertilizers will work well. You can also substitute a rose fertilizer if you want.

Apply an application of the insecticide just after flowering is finished in the spring if it is needed.

— Bob Morris is a horticulture expert living in Las Vegas and professor emeritus for the University of Nevada. Visit his blog at xtremehorticulture.blogspot.com. Send questions to Extremehort@aol.com.