Today, I caught my first imported cabbage moth in the high tunnel. More importantly, the moth crossed my radar before its larva, the imported cabbage worm, has had a chance to eat all of my turnip leaves.
Scouting is an important tool we use in the garden and landscape to stop problems before they have a chance to get out of hand. It's good to get out in the garden every day, checking plants for insect damage, disease, adequate water and fertility, and it's a good excuse to be outside. My daily scouting routine in the high tunnel usually ties into normal plant maintenance and watering.
Sometimes problems are evident, as was the cabbage moth. My arrival in the high tunnel was heralded by a flurry of white moths with a single black spot on each wing, flitting from turnip to turnip laying their eggs. Other problems are not so easy to see and require a gardener or landscaper to inspect the top and bottom of leaves closely, touch the soil to check for moisture, feel for ripeness of fruit, and so on. Some potential problems require help to diagnose.
My positive identification of the cabbage moth was near certain, but to be sure my next step was for confirmation. After a gentle capture of one offending moth, she quickly became a subject centered in the lens of my camera. I sent my photos to colleague and entomology guru Ken Johnson in Jacksonville. Ken confirmed the suspect as imported cabbage moth, which then propelled me to begin control measures.
The larval form of imported cabbage moth is known as imported cabbage worm (a caterpillar). These caterpillars can become quite destructive as they feed on plants in the brassica family, such as kale, turnip, bok choi, broccoli, and others.
Luckily the control is the simple application of a pesticide containing the active ingredient Bt (Bacillus thuringiensis), a microbe naturally found in soil. Always follow label directions and take steps to minimize exposure regardless if the pesticide is 'au naturel' or engineered in a lab.
This year I'm looking forward to caterpillar-free turnips and turnip greens.