My Meyer Lemon tree was having a good summer on the deck. It liked our extra heat and put out a lot of new leaves. I bring it inside for the winter where it usually sulks and loses leaves but it does usually blossom a few times and I love the smell. One of the sweetest smells there is.
Other citrus trees that have gotten this treatment have had scale once I bought them indoors that I would have to fight. The last one gave up and died. But they’d never had scale outside and I blithely believed that with my healthy, bug-friendly back yard, they never would. They have a lot of predators to keep their numbers down. I saw the black spots, and went hmmm, will have to wash that off and procrastinated. Then I saw the ants; lots of them. Took a closer look and recognized my old citrus enemy, scale.
- Scale
Did some reading; the sooty mold and the ants should have told me right away what the problem was. They are both an indirect result of the sugary substance that the scale secrets. It drips on the leaves and feeds the mold and the ants love it. The ants may even have helped deter predators as part of their symbiotic relationship with the scales.
So first, my sources said, get rid of the ants. Before these pictures were taken, I sprinkled diatomaceous earth around the stem of the plant. It may have reduced the numbers but there were still some pretty happy ants a few days later. After losing the last plant, I’d determined to use a horticultural oil before bringing the plants indoors for the winter so, after some research, I decided to try Bonide’s All Season’s Horticultural Oil, now. The temperature range should be good for the next few, dry days. Too warm or too cold and it may not work or worse, further damage the plant. And it will wash off in rain.
I also pruned the plant and took out everything beyond the bad infestation in the picture, branches that were crossed or that had no leaves. The baby scale is so small that it may take multiple treatments to eliminate the population, if that’s even possible. The horticultural oil that I chose can be used on houseplants so I will be vigilant. I’d also planned to try the LED lights with some larger plants this year, just not sure about introducing a plant with pest problems into the environment where I grow things from seeds.