Scale can be difficult to control

Q: All my plants, especially my houseplants, are having a hard time acclimating from California to the dry, hot, Las Vegas climate. I am attaching a few photos of a problem I am having with my ficus, bird of paradise, palm and umbrella tree. They all have some type of scale. They are all losing their leaves; the leaves on the ficus turn yellow and drop off while the umbrella tree leaves dry up brown, curl and fall off. The same is happening with the palm. The scale is a reddish brown and there is a sticky residue on the floor around the plants, like someone sprayed sugar water or light syrup. There are several droplets like syrup on the plants also. I have washed off the palm with soap and water, but it is impossible to do this with the other plants.

A: All three pictures that you sent to me were very blurred. I think, however, that the last picture was enough for me to get an idea of the scale problem. This particular scale looks like medium brown bumps covering the leaves and stems and is probably a brown scale.

There are two approaches to controlling scale insects, but first let’s talk about their life cycle. They basically have two stages. One stage, the scale stage, is easy to see since they don’t move around. This is the stage where they find a place where they can feed on the plant and build a hard covering around them called a scale.

The other stage is more difficult to see. This is the mobile stage where they move around on plants to find a sex partner and lay their eggs. The unprotected young ones move around to find a place to feed. Once they find a place to feed they then build that protective scale around themselves.

To control the insects once they have built that protective covering, you must use either an oil that can suffocate them or apply a poison to the plant that will kill the insect as it feeds on poisonous plant juices. One horticultural oil that is usually available is called Volck Supreme and is made by Ortho, but there are others out there that will work great.

Once you have controlled the insect, the scale will persist on the plant and may be unsightly. Once the protected insect is killed, the scale should lose some of its color and indicate to you that the insect underneath it is dead.

The other way to kill the insect is to focus on the stage not protected by that hard outer shell. During their mobile stage they are soft and very vulnerable to insecticides and much easier to kill. It is also a time that is much more difficult to determine because it is random and the insects are difficult to see when they are moving about. Soaps will give good control at this stage but must be repeated so that you catch several emerging generations.

The problem with applying oils and suffocating them is that some oils may be toxic to some houseplants. So if you go this route, try the oil on a couple of leaves first before applying it to the entire plant. Always read the label!

As the plant continues to grow, protect the new growth with oils or insecticides. Keep infested plants away from other plants that might not be infested until control is achieved.

Q: I would like your advice on staking a grapevine. I remember my father staking it to the fence. I would like to stake a grapevine along our driveway.

A: A grapevine needs to have room to grow behind the supports as well as in front of it. Chain link fences are big problems when growing grapes on them since they get all intertwined on the chain link and can be difficult to harvest and prune.

Grapes can be grown on a trellis, an arbor or freestanding without wires or fencing when supported by a T-post. The T-posts can be spaced about 4 to 6 feet apart. The central trunk is staked to the T-post and the vines are left sprawling from the trunk and cut back each year to one-year-old spurs or canes, depending on the variety.

Q: First, can you send me a list of the fruit trees that are good for Las Vegas? We want to plant a peach and a couple of apple trees. I would like apples that are good to eat and cook. Second, I have a pear tree that is about five years old. I don’t remember what kind it is but the pears are bumpy with brown blemishes so perhaps it is a Bartlett. I don’t seem to be able to get the fruit to ripen. I have put them in the refrigerator for a few days and then on the kitchen counter. I have also put an apple in with them as I heard that helps. They don’t seem to ripen, just stay hard and then spoil. Any suggestions?

A: You will get the fruit tree list as soon as I release it. I have a waiting list of a couple hundred people who have contacted me as well.

Apples can be a bit of a challenge and don’t seem to get the same quality as they do in some other locales with a few exceptions. In general, look for late-developing apples like Pink Lady, which has done extremely well here.

However, early apples that are good include Dorsett Golden, Anna and Mutsu. Gordon is another that does alright. Pink Lady is probably the best of the group.

Pears get blemished here. That is what a pear growing in the desert looks like. It can still develop excellent flavor and texture here.

It sounds like you are picking them too early. If they are picked at the right time (just as the background color is changing from dark to light green and the seeds are 95 percent dark brown) they will finish at room temperature into an excellent fruit.

If picked too early or if you are trying to ripen wind-fallen fruit that is too immature, the fruit will either not ripen or it will ripen with very poor flavor and poor sweetness.

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.