Problems with canary palms usually caused by water allocation
Q: I have a canary palm in my yard that looks as if it’s dying, or at least the fronds are. If you look closely, even the fronds towards the center appear to be drying out. Have you seen anything like this? Can anything be done?
A: Usually when this kind of thing happens in palms, it’s water-related —either too much or too little water.
When we’re talking about too much, we don’t mean overwatering in a single application, we mean watering too frequently, which doesn’t let the soil dry out between irrigations.
These palms can use a fair amount of water. So, if they are in a desert landscaping they really need a lot of water in one application — 50 or 60 gallons.
These palms perform really well in a lawn or surrounded by other high-water-use plants. These are oasis plants, not true desert plants. But they don’t like soils that are constantly wet.
Another possible, but less likely, cause for this condition are disease or insect problems. There is a disease problem that can attack the central bud at the top of the trunk, weakening it and eventually killing the tree. If this is the problem, there is little to do but wait it out and hope for recovery.
There is an insect called the giant palm borer that can attack the tree’s trunk, weakening it and eventually killing it. You’d see holes in the tree’s trunk about a half-inch in diameter; these are exit holes the adult beetle has flown from.
I would concentrate on whether the tree is getting not enough water or is being watered too often. If you suspect a lack of water, flood the area under the tree with the hose once a week over the next month to see if you can get it to recover.
If the irrigation system is coming on several times during the week, you consider whether you’re watering too often, keeping the soil too wet. Give it more water during irrigation, but do it less often.
Q: We live on Mount Charleston at 5,000 feet, and after the forest fire and flood, we planted seven Mondell pines along our property. The pines made it through the first summer and winter and have grown nicely but developed a cotton on the tips of the limbs.
A: This cotton on the end of the limbs is the natural color of the buds on the ends of shoots and branches as they expand into new growth.
The white color, or cotton as you call it, are the sheaths enclosing the bottom of the new needles as they expand. The buds first expand and grow longer and wider. Depending on the tree’s health, this expansion can be fairly short, an inch to an inch and a half, or quite long, perhaps up to 4 inches.
In this stage they are called “candles” because they resemble a small thin candle at the end of the branch. Pines are somewhat unique in that all of the needles of the new growth, and all of its new growth for that matter, are contained in this candle.
The amount of new growth and how dense the canopy is can be managed by breaking these candles with your fingers. Do not cut them or you will damage the needles emerging from the candle and they will turn brown.
If you want to keep the tree smaller and more compact, break about half of the candle off when it emerges. This removes half of the new growth that can develop and causes more side branching to occur, thus making the canopy denser.
This is a handy management tool if you’re using these trees for screening or windbreaks. Do not be alarmed, this is normal for this tree.
Q: My young peach tree had leaf scorch when I bought it, and it got progressively worse as it got hotter. The leaves have all of these red spots all over it. Is this a disease or is it because of the heat?
A: This is a disease we see on peaches and nectarines called shothole fungus, sometimes also called Coryneum blight.
Your picture shows the disease developing on the leaves first as reddish spots. The disease kills the leaf in these reddish spots and the dead area drops out of the leaf leaving a hole about the size of a BB.
Under more humid conditions, this disease spreads to the fruit giving the fruit the “measles.” The fruit is OK to eat but it looks ugly and impossible to sell or even give away. Here in the desert with our low humidity I have never seen it spread to the fruit.
Based on observations I’ve made over the years, it seems to me that some peach and nectarine varieties, even some apricot, are more susceptible to this disease than others.
Also, I see it more often on trees that aren’t watered properly or have gone through some drought. On one particular variety, I have seen this disease totally defoliate the tree, and the tree puts on new leaves and is fine the rest of the summer.
What to do? Make sure the tree is being watered correctly and it is not going through drought stress. If you can let the disease go and it does not attack the fruit, then you might just live with it. However, defoliation year after year will weaken the tree and make it less productive.
Fungicides that contain copper, such as Bordeaux mixture, can be sprayed on the tree limbs immediately after leaf drop in the late fall. Secondly, you can spray the new leaves that come out in the spring with the same fungicide to protect leaves and fruit from getting infected.
If this recurs year after year and you have done everything you can, consider replacing the tree with a different variety.
Q: I am finding a large worm, varying from 2 to 5 inches in length, on my grapevines. It is roughly ½ inch in diameter. The body color varies: Green, pink, gray and brown worms have been removed and destroyed. Each worm has white diagonal stripes over the length of the segmented body. What is it, and how do I avoid it in the future?
A: This is a hornworm and they love tomatoes, peppers, eggplant, potatoes and grapes.
You will notice a stiff, semicurved spine sticking up from its rump, too. This spine contributes to its name.
This is a larva or immature form of the hummingbird or sphinx moth. The moth began laying eggs sometime in around March and April so the hornworms have been damaging garden plants since then.
Hornworms are voracious eaters and can defoliate a plant in a very short time, leaving it leafless. Their green color makes them hard to see on garden plants even though they are large. Their excrement is large so seeing that is another way to tell whether they are feeding.
If you have a blacklight used for “seeing” bark scorpions at night you can use this at night as well. Hornworms “fluoresce” or shine green at night from a blacklight and usually can be easily found this way.
Control is fairly easy by handpicking as you have done or use the same biological spray used for grape leaf skeletonizer or tomato fruitworm: Bt or Spinosad. Both Bt and Spinosad can be used by organic gardeners safely.
Spinosad is a little rougher on bees than Bt so it is always best to spray any pesticide at dusk or early dawn when bees have not started to forage. Always follow label directions for use.
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.