Central bud critical to palm’s survival

: In March of this year, I had a pindo palm planted. Initially, the plant did very well; however, now the fronds are all brown and brittle. I gently tugged on the center fronds and the entire center came out. The base was mushy and there were tiny worms as well. Does this mean my palm is history? Please help!

A: Yes, I am afraid the palm is history. You have described exactly what we generally call palm bud rot. This is where the central growing point, or bud, of a single-stemmed palm dies. It is a disease and can be caused by a number of different organisms, such as fungi or bacteria. The worms or grubs are decomposers of rotting plant parts.

The first symptom is usually a yellowing of the young leaves surrounding the central bud. When the central bud dies there is no way for a single-stemmed palm to continue to grow because all of the new growth comes from that bud. It may take months after the bud dies but eventually all the leaves along the central stem or trunk die.

In our climate, a common cause of palm bud rot is planting in the fall or during cold weather. This is one example of a plant that should not be planted then. It performs best if it is planted during summer months.

There is some claim that during early onset of palm bud rot, when there is slight discoloration of the leaves of that central bud, a drench of a copper-based fungicide applied to the bud may help it recover. Obviously, for yours this is too late.

Q: I have been having some problems with my plants. I am in Reno, but I hope you can help me. My lilac and rose leaves have been eaten around their edges and I see some small black droppings on them. I also see some white/brown residue on the rose leaves. I have sent you some pictures.

A: I am in Las Vegas but we have these same problems here. (Readers can see these pictures posted in my free, weekly e-newsletter. Subscribe to it by sending me an e-mail at morrisr@unce.unr.edu. There are no advertisements and no spamming.)

You are right. The leaves around the edges of your lilac have been eaten, causing an irregular notching. The insect pest responsible for this is a root weevil. These insects are small, usually not more than about 1/4 inch long.

The adults lay eggs in the soil underneath their food supply. When the eggs hatch, the grubs or larva feed on plant roots. If there are lots of them, they can collectively weaken the plant. As the larva mature into adult weevils, they can climb from the soil and begin to feed on the edges of leaves causing the notching that you’re seeing. They usually climb from the soil and feed at night so you seldom see them.

One method of control is to hand pick or vacuum them from your plants at night when they are feeding. Another method is to shake them from the plant into a bucket of soapy water, again at night. A third method would be to use a product called Tanglefoot, which is sticky and can be applied to a single-stemmed plant and captures them as they try to climb.

A fourth and final method is the use of pesticides. You would apply the pesticides to the leaves at dusk and to the soil surrounding the plant. Make sure the product is approved for use on these plants and read and follow the directions on the label.

The second problem is called powdery mildew of roses. This is a fungal disease that attacks plant leaves and, in some cases, flowers, leaving behind a white powdery substance.

This particular disease usually affects plants that are growing in shady locations with poor air movement and, frequently, splashing water. This splashing water can be from overhead irrigation such as sprinklers or rain. The water landing on infected parts can move the disease from leaf to leaf and plant to plant.

Powdery mildew comes in many different types and is usually very specific to certain types of plants. For instance, the powdery mildew on roses will not cause powdery mildew on lawn grasses.

Usually, I recommend that you try to get more light on these plants and create more air movement in some way. Do not water at night and avoid overhead irrigations; drip irrigation would be better.

There are fungicides that can be applied during the time of year when powdery mildew is most likely, such as the fall or spring. It also may become a problem right after it rains or when humidity is high.

Q: I know this is the time to prune our plants, but how to prune is the question. I have a line of mock orange bushes in my yard and Texas sage. My husband wants to take the clippers to the sage to shape them and cut the mock orange about 6 inches. The sun has burnt the tops.

A: The time for pruning can extend from now until early spring, just before new growth appears. So, you have lots of time.

The mock orange is a slow grower so recovery from pruning will be slow. If the sun has burnt the tops, my guess is they were planted in rock mulch and a very hot location. Mock orange can handle the reflected heat from rock mulch on the east and north sides of a building but not the south and west sides very easily.

Your plants may have been planted in the wrong location. Mock orange will begin to fail when planted in rock mulch in hot locations in about five years or less. You might want to consider moving them or replacing them.

Simply cutting them back may not correct the problem. The risk you have by cutting them now is that if they look ugly, they will look ugly for many, many months. If you delay pruning them until February and they look bad, they will only look ugly for months.

Regarding your Texas sage, the correct way to prune it would be from the base. It will not take shearing for more than just a few years. Find two or three of the largest stems and cut or remove them as close to the ground as possible. This will cause new branches to sucker from the base and keep the plant juvenile and full of leaves and flowers top to bottom.

When you continue to shear Texas sage, eventually all the leaves and flowers will be on the perimeter of the shrub and gradually the shrub will become more and more woody from the base. However, if you like this look, then disregard my advice and realize it is an unnatural form.

Bob Morris is an associate professor with the University of Nevada Cooperative Extension. Direct gardening questions to the master gardener hot line at 257-5555 or contact Morris by e-mail at morrisr@unce.unr.edu.