As with many plants, we first notice a problem with plumeria when leaves start to turn yellow, then brown and drop off. Or we are delightedly waiting for buds to burst into color, but the buds never open or drop off. Assuming the plumeria has the correct environmental conditions such as sufficient light, appropriate water, and fertilizing schedule, examine the plant for pests.
Common Plumeria Pests
Plumerias are subject to many of the same pests as any other garden plants. The most common of which include:
In addition to the pest above, there is one more commonly found insect that affects this plant – the caterpillar of the Tetrio sphinx moth. Plumeria just so happens to be its primary host plant.
Identifying Plumeria Pest Problems
Examine the leaves on top and bottom, looking for any pest problems. Spider mites, a sucking insect, are smaller than a pin head but can be identified by webs between the leaf ribs. To check for whiteflies, shake the plant stems and leaves. If small insects fly out, you likely have a whitefly infestation.
Now examine the leaves and stems for white, fluffy, sticky clumps, especially where the stems attach to the plants and along the edges of the leaf ribs. With a magnifying glass, you can see these are mealybugs. If you found brown, raised bumps along the stems and leaf ribs, you are dealing with scale.
Thrips generally reside inside the buds of plants. They are difficult to see until you pick off a bud and set it on a plate. Soon, you will see small, black bugs that look like a rye seed crawling out of the flower bud.
In some areas, slugs and snails are plumeria plant pests. Portions of the plant stem will have been chewed away and slime trails may be visible near the plants.
Damage from caterpillars will come in the form of chewed leaves and defoliation of the plant.
Treating Plumeria Insect Pests
The first, easiest, and least expensive pest control for plumerias is to spray the plants with a strong jet of water. This creates a moist environment to discourage spider mites which prefer dry, dusty conditions. The spray dislodges whiteflies and kills them by drowning them or breaking off their mouth parts so they die. If a jet of water fails, spray the plants with insecticidal soap to suffocate the insects.
Water does not impact scale and mealybugs. Both of these plumeria plant pests create a waxy protective shell preventing pesticides from penetrating. For these common plumeria pests, treat them with cotton swabs dipped in rubbing alcohol. Dab each bump or white sticky patch with rubbing alcohol to kill the insect under its protective shell.
Diatomaceous earth is a good choice for treating plumeria pest problems such as slugs and snails. Spread it on the ground around the plant.
For the most part, the caterpillar pests can be picked off by hand and tossed into a bucket of soapy water. Of course, if you’re a bit on the squeamish side, this probably isn’t something you want to do. Should this be the case, you’ll be happy to know that most caterpillars can be controlled with the use of Bacillus thuringiensis.
If the above methods do not eliminate your plumeria plant pests, you may need to resort to systemic insecticides, recommended by your local garden center.