Arugula, a fast-growing leafy green, is a popular choice for its peppery flavor. While relatively low maintenance, arugula plants are susceptible to various garden pests. These pests can compromise plant growth and yield, making effective pest control important for a healthy harvest.
Identifying Common Arugula Pests
Identifying specific pests affecting your arugula is the first step in addressing issues. Each pest leaves distinct signs, aiding in accurate diagnosis and targeted management.
Flea Beetles
Flea beetles are tiny, dark-colored insects, typically black or bluish-black, about 1/10 inch long. Named for their ability to jump when disturbed, these beetles are drawn to arugula and other mustard plants. Their feeding creates small, rounded “shot-hole” damage on leaves. Heavy infestations can severely damage young seedlings and render leaves unmarketable.
Aphids
Aphids are small, soft-bodied insects, 1 to 3 millimeters long, appearing in various colors like green, gray, yellow, or black. They cluster on new growth and the undersides of leaves, often in large colonies. Aphids feed by sucking sap, leading to curled or distorted leaves, stunted growth, and a sticky “honeydew” residue. Significant infestations impact plant health and make produce unappealing.
Cabbage Worms
Cabbage worms are the larvae of white butterflies, sometimes called cabbage whites. These velvety green caterpillars, up to 1 inch long, often have faint yellow stripes. They chew large, irregular holes in arugula leaves, leaving dark green fecal pellets. Cabbage worms can cause considerable defoliation, especially during seedling establishment.
Slugs and Snails
Slugs and snails are soft-bodied mollusks most active during damp conditions and at night. They leave irregular holes in leaves, often starting from the outer edges, and can consume entire young plants. A telltale sign is a shiny, silvery slime trail on leaves and the ground. These pests hide in moist, dark places during the day, such as under debris or in soil crevices.
Preventing Arugula Pests
Proactive measures minimize pest infestations on arugula plants. Healthy plants are more resilient to pest attacks, and certain cultural practices create an environment less appealing to common pests.
Proper plant spacing allows for good air circulation, reducing conditions favorable to some pests and diseases. Healthy soil, with organic matter and balanced nutrients, supports robust plant growth. Consistent watering prevents plant stress, as stressed plants are more vulnerable to infestations.
Physical barriers like floating row covers reliably keep many insect pests, including flea beetles and aphids, away from young arugula plants. These lightweight fabrics allow sunlight and water to pass through while creating a physical barrier. Crop rotation, which involves not planting arugula or other Brassica crops in the same spot year after year, disrupts pest life cycles and prevents populations from building up in the soil.
Companion planting can deter pests by interspersing arugula with plants that repel them or attract beneficial insects. For example, planting basil or mint near arugula may deter pests. Maintaining garden hygiene by removing plant debris at season’s end eliminates overwintering sites for pests.
Managing Arugula Pest Infestations
Once pests are identified on arugula, several organic and non-toxic methods can manage infestations without harming the edible crop. These techniques focus on direct removal or natural controls.
For larger pests like cabbage worms, hand-picking them off leaves is an effective direct approach, suitable for smaller infestations and regular application. A strong spray of water can dislodge aphids from plants, especially when focused on the undersides of leaves. This can be repeated every few days until the aphid population is reduced.
Insecticidal soaps are an option for soft-bodied pests like aphids. These soaps suffocate insects on contact and are safe for edible plants when used according to instructions. Neem oil, a natural insecticide from the neem tree, deters and kills pests by disrupting their feeding and reproduction. When using neem oil on delicate leafy greens like arugula, apply with caution to avoid foliage burns. Apply in early morning or late evening to avoid direct sunlight, which increases leaf damage risk.
Introducing beneficial insects, such as ladybugs and lacewings, provides natural pest control as they prey on aphids and other small insects. These natural predators maintain a balanced garden ecosystem. Bacillus thuringiensis (Bt) is an organic bacterium that targets and kills caterpillars like cabbage worms without harming other organisms. Applied as a spray, Bt is a suitable organic choice for managing these leaf-eating pests.