Ask Your PCA: What are the best ways to deal with celery pests?

Celery is grown throughout the winter on the South/Central Coast. Early plantings of celery start in August and continue through March.

The main pest pressure in the fall is beet armyworm. There are a couple of hatches between September and the middle of October. Once the days become shorter, the worm pressure decreases.

Armyworms rout out the shanks of the celery, and the outside shanks have to be peeled off. This reduces the size of the celery.

Chemical treatments are applied to control armyworms. Some growers use pheromone traps, but the moths are visible in the field along with the egg masses.

Growers have more chemicals at their disposal than in past years, allowing for better control of this pest.

Green peach aphids are another fall pest of celery, and neonicotinoids are used to control them.

Organic growers fight aphids year-round. There are some chemical applications available for organic, but they are not really effective. Beneficials can be used, but they won't completely eliminate the aphids. As soon as there are signs of aphids, begin treatment immediately to prevent large numbers from building.

Celery leafminer can also be a problem. Typically, there is higher pressure in the fall and during a warm spring.

Leafminers damage the celery, making it unmarketable, and also provide an entrance for disease. Pesticide treatments are used to control this pest.

During the winter months, late blight can become an issue. Early symptoms of late blight consist of small, yellow spots on leaves and petioles. As the disease progresses, leaf lesions enlarge and usually grow together.

Chemical treatment is not necessary when field temperatures remain below 55 degrees. Monitoring celery fields for late blight symptoms is advised. If the disease is detected, fungicide applications should be made, particularly if sprinkler irrigation is used or there has been rain.