I love the look of a potted lemon tree with lemons growing on it. So I bought a lemon tree that had been grafted onto dwarf stock, and planted it in a nice big pot. I set it up with a drip line for watering, positioned it on the patio near the swimming pool, and admire it every time I see it.
You can just imagine my anger and disappointment to discover one morning that I wasn’t the only one who was noticing the tree. Something was eating the leaves! This mysterious critter seemed to favor the fresh new leaves. I looked closely in the soil of the pot and on the leaves and didn’t see any insects. I suspected snails because the leaves had big chunks chewed out of the edges, but I didn’t see that slimy trail that snails leave. The damage continued and it seemed to be happening at night.
My next step was to go out at night with a flash light and look for the culprit. That was when I discovered, not snails, but three little earwigs munching away on different leaves. I picked them off and mercilessly threw them into the swimming pool. The next day I researched earwigs on the UC IPM web site, so that I could learn more and try to prevent them from returning.
Earwigs are little insects that come out at night and hide during the day. They hide in the soil and under leaf litter. I really didn’t know how they were getting up into the pot, but I assumed they were probably in the soil. I tried a few things to keep them off the lemon tree. I made an earwig trap from a piece of rolled up newspaper thinking that would give them a place to hide during the day and I could throw them out when I found them. I also set out a little tin can partially filled with vegetable oil that was supposed to entice them and then they would drown. I also bought some gummy resin (called “tree tanglefoot) that would trap them as they climbed up the trunk. (The gummy resin should not be applied directly to the trunk of the tree, so I wrapped the trunk in quilt batting first and applied the resin to the quilt batting).
I checked the tree every day for weeks. I caught a few earwigs in the oil and a few in the sticky stuff, but I never did find any in the newspaper trap. The chewing damage stopped and the tree recovered. It had a nice spurt of growth during the rest of the summer and now there is a beautiful lemon ripening on the tree. I felt like a detective who had solved a mystery!
Earwigs, however, are not the only pests that attack a lemon tree. We had another pest take a liking to our tree and its damage still persists. It is the citrus leafminer. Citrus leafminers are small moths that lay their eggs on the upper and lower surfaces of citrus leaves; they are particularly attracted to new foliage. The caterpillars hatch and eat their way through the leaf, making little curved trails as they munch away and grow. The serpentine mines on leaves are a dead give-away in identifying the pest. The leaves are damaged and distorted, but the fruit is rarely touched. If the fruit showed the serpentine mines, then that would be caused by another insect moth called the citrus peelminer. Natural insect enemies can keep this pest under control for the home gardener and pesticides are not recommended because the caterpillars cannot be reached by the spray when they are mining the leaves.
There are several other pests common to citrus grown in the San Joaquin Valley, but most are only occasionally problematic in home gardens. The list includes the citrus red mite, California red scale, citricola scale, cottony cushion scale, citrus thrips, the fork tailed katydid, glassy winged sharpshooter, and whiteflies.
The greatest concern is over the Asian citrus psyllid because it carries the devastating citrus greening disease (huanglongbing), which could destroy our important citrus industry. More information on all of these pests can be found on our Master Gardener web site: tinyurl.com/4cxudpuj.
This column is not a news article but the advice of the writer and does not reflect the views of Mid Valley Times newspaper.