orange tree

Question: I have ants crawling up into my orange tree and also squirrels climbing the tree.
How do I deter these pests?
-Nanci Zellman,
Sherman Oaks
Answer: Ants climb a tree not because of anything the tree has to offer them directly but because of an indirect benefit. If you look carefully, you’ll see that some of the ants climbing your tree carry sucking insects, such as aphids and mealybugs, with them. These insects, along with whiteflies and scales, produce so-called honeydew or undigested plant sap, exuded from their digestive tract.
Aphids, in particular, are noted for their honeydew production, which is increased by virtue of a symbiotic relationship with ants.
Ants utilize their antennae to stroke or “milk” aphids, inducing them to produce extraordinary amounts of honeydew, which the ants consume. In return, ants protect their aphid “cows” from predaceous insects. During winter, some ants store aphid eggs in their nests and then carry them to succulent young leaves in spring. As soon as the aphids hatch, they begin to suck leaf sap and produce honeydew for their ant masters.
You can find products, such as Tanglefoot, that provide a sticky physical barrier to ant traffic up your tree. Wrap an old silk stocking around your tree trunk and slather it with Tanglefoot. (Petroleum jelly, for that matter, would probably work just as well.) Ants will literally get stuck in their tracks as they attempt to climb the tree. You may have to change the stocking from time to time as ants will use the bodies of their dead comrades, stuck closely together, as a bridge over the sticky stocking.
As for squirrels, dangling old CDs or hanging bags of mothballs from branches may both act as deterrents. Alternatively, you can procure a motion sprinkler which is activated, in the manner of a light with a motion sensor, when squirrels or other animals are in the area. It releases a jet of water that deters the critters.
Q: My white birch trees that were planted 61/2 years ago are not coming out with any green leaves. They look like they looked all winter. I think they are dead. I’ve noticed that others in the neighborhood look like this or look like they are struggling.
Also, my Japanese maple has some dead branches, although most of the branches have leaves. If I have to remove the birch trees do I need to treat the soil before replanting? Would you suggest planting some other kind of tree?
-Diane Hill, Chatsworth
A: If you cut back on their watering when the new water regulations took effect last year, this could have affected their vitality, as well as that of the other birches in your neighborhood. Birch trees need more water than any other commonly grown tree, although Japanese maples are also somewhat water needy. You could replace your birch trees with more drought-tolerant trees such as crape myrtle, Australian willow, bottlebrush (Callistemon), or paperbark (Melaleuca quinquenervia).
The picture you sent could also explain the death of your trees. They are planted in a low spot and their roots could have rotted as a result. Even though birches are thirsty trees, their roots are sensitive to prolonged exposure to standing water, which might have been present during this year’s extended rainy season. If you wanted to plant more birch trees in that same location, you should do so after raising the soil level to eliminate the low spot.
As for Japanese maples, alkaline salts in our water are implicated in their burnt leaves and defoliated branches. As an antidote to this problem, acidifying vinegar is recommended. Add one tablespoon of vinegar to a bucket of water and pour the contents over the soil around your Japanese maple, changing soil pH by washing out the salts or, on a monthly basis, you can just leave a trickling hose next to your tree and this will carry the salts down and past its roots.
Q: I’m a flower lover and I have a hibiscus that has flowered very little this year. I feed it with hibiscus food.
I also have a climbing rose that hasn’t flowered for the last two years. I feed it and water it like my other plants. I have other plants that flower just fine except for these two. What am I doing wrong? Also I don’t have any room to plant a fig tree, can I plant a fig tree in a pot?
-Esperanza Gilmore, West Hills
A: You may have overfertilized, which would inhibit flowering. Excessive fertilization, especially with a high nitrogen fertilizer, may cause excessive vegetative or leaf growth at the expense flower production. The only other reason hibiscus and rose plants would not flower is that they are not receiving sufficient light. They need at least four daily hours of good ambient light to bloom.
You can definitely plant a fig tree in a container. There are dwarf varieties such as “Petite Negri” and “Black Jack” that grow less aggressively than most fig trees but any variety can be managed with the proper pruning technique. To manage the size of any fig tree, you simply pinch or cut stem tips after six leaves have formed on the stem.
Utilizing this technique, you can keep fig trees at a height of five feet or less and you will increase fruit production in the process.
Tip of the Week
For long-blooming summer color, consider trumpet vines. You encounter them in yellow, orange, red, purple and pink. Pink trumpet vine (Podranea ricasoliana) is a rampant grower that is seldom planted but deserves wider use. It does not have tendrils and must be tied, at the beginning, to the fence, trellis, or pergola that you want it to climb. However, once it develops a vertical orientation, it can stand on its own and may also be used as a hedge or screen.