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Sap Sucking Scale!


Sap Sucking Scale!

Do you see “honeydew” on your plant’s leaves? (Honeydew is partially digested sap; it looks like little sticky droplets) Are leaves turning yellow, and your plant seems to have stopped growing? If you peer closely at the tops or the undersides of the leaves, do you see small roundish brown bumps on them, randomly scattered, but mostly along the petiole. If you look closely on the twigs and stems near the tips of the branches some of what you thought were bumps of bark, may also be SCALE!! Outdoors ants may also be present as they find the honeydew tasty. Scale insects pierce the leaves and stems and suck the sap from plants causing them to lose vigor color and in severe cases lead to extensive leaf yellowing, premature leaf drop, branch dieback and death of the plant.

There are over 3,000 species of scale insects in North America. Scale are related to MEALYBUGS, but instead of being white a waxy, scale have a hard shell that is their exoskeleton. Color is most often brown but can be reddish or greenish. The females in the young stage find a place to feed. She will develop the protective covering and lose the use of her legs, remaining in one spot for the rest of her life. Males emerge as yellowish 2 winged insects with 3 pairs of legs and antennae. They move about and mate with the stationary females and then die. The females lay eggs (some species have live birth). The eggs hatch under the shell, and then crawl out to find a place to feed. This may happen as many as 6 times a year, May, June, August and September. That’s NOW! Indoors the cycle goes on unchecked. And they love warm humid environments like greenhouses. To make matters worse scale insects lay more eggs and survive better on plants receiving a lot of nitrogen.

Plants that are attacked include fruit trees, ash, camellia, cedar, crabapple, dogwood, elm, honey locust, juniper, lilac, maple, oak, pine willow, houseplants like hibiscus, holly, ixora and ficus, etc. Sounds like the meal ticket for the Tasmanian Devil in a Bugs Bunny cartoon.

Under outdoor conditions the population may be controlled somewhat by natural predators such as lady bugs, green lacewings, wasps, and parasitic fungi. Some insects can be mechanically removed by scraping them off with a fingernail, knife or washed off with a hose. But chemical control will be needed for most infestations. Dormant oils like Volck’s oil can be used in the early spring. Neem oil can be used to interrupt the life cycle. Because of their shell like body, it takes a good soaking to penetrate the shell and kill the insect. Some plants (like Fukian Tea) may loose all their leaves from treatment. Systemics can also be used with some success, but these usually are combined with a fertilizer, and right now it is to late in the season to be applying a fertilizer with nitrogen, so read the label before doing this on outdoor plants. You might getaway with this on tropicals, if you don’t have leaf eating cats or other pets when you bring them in doors in October.

I heave read that using a Q-tip with isopropyl alcohol works, but alcohol can also kill some plants leaves, so test an area first. Sagaretia Teazans is one that doesn’t like this. Some sources say use insecticidal soap like Safer’s. These articles if read closely go on to say frequent reapplications may be necessary; like after every rain to remain effective. This year would be a lost cause, but most soaps are safe around pets. And for indoor use, you can even make your own mixture of dishwashing soap in water with rubbing alcohol.

Whatever method you choose, now is a good time to start to keep from bring unwanted hitchhikers from having a mid-winter population explosion on the plants you need to bring indoors.