Nasturtiums are popular garden plants, valued for their vibrant, edible flowers and peppery leaves. While generally robust, nasturtiums can attract common garden pests, and this guide helps identify them, recognize damage signs, and implement effective control and prevention strategies.
Common Nasturtium Pests
Aphids are small, pear-shaped insects, typically 1/10 to 1/8 inch, appearing in various colors. They cluster on new growth and undersides of leaves, feeding on plant sap.
Cabbage worms are velvety green caterpillars, the larval stage of white butterflies. They have faint yellow stripes and are frequently found chewing on nasturtium leaves.
Flea beetles are tiny, shiny insects, 2 to 4 millimeters long, often black, striped, tan, or brown. They jump quickly when disturbed and are typically observed on foliage.
Slugs and snails are soft-bodied mollusks, identified by the shiny mucus trails they leave. They feed at night and hide during the day in damp, dark places.
Spider mites are minute, eight-legged arachnids, often less than 1/50th of an inch. Yellowish or reddish, they reside on leaf undersides. Fine webbing indicates their presence.
Whiteflies are small, moth-like insects, 1/16 to 1/8 inch long, with yellowish bodies and waxy white wings. They fly up in a cloud when disturbed from leaf undersides.
Signs of Pest Damage
Pest infestations on nasturtiums manifest through several visual cues. Chewed leaves with holes or ragged edges often indicate larger pests like cabbage worms, slugs, or snails. Flea beetles create tiny pin-hole marks across the leaf surface.
Leaves may show yellowing, curling, or distortion, symptoms of sap-sucking insects such as aphids, whiteflies, or spider mites. These pests extract fluids, leading to weakened or stunted plant growth.
A sticky residue, known as honeydew, often appears on leaves and stems, indicating aphid or whitefly infestation. This sugary substance can lead to sooty mold, a black fungus. Fine, silken webbing on leaf undersides signals spider mites.
A shiny, slimy trail across leaves or the ground confirms slug and snail activity. In severe cases, these mollusks can devour young plants or strip leaves down to their veins.
Controlling Nasturtium Pests
Physical removal effectively manages many nasturtium pests. Hand-pick larger pests like slugs, snails, and cabbage worms, especially during early morning or evening. For smaller insects like aphids, whiteflies, and spider mites, a strong stream of water dislodges them. Prune and dispose of heavily infested leaves or stems to reduce populations.
Organic sprays offer another defense. Insecticidal soaps are effective against soft-bodied insects by disrupting cell membranes. Neem oil controls aphids and spider mites by interfering with their feeding and reproduction. A mild solution of two and a half tablespoons of dish detergent per gallon of water can also be used for aphids.
Encouraging beneficial insects is a natural biological control. Ladybugs, lacewings, and hoverflies prey on aphids and other small pests. Parasitic wasps help control cabbage worms. A diverse garden environment with nectar-producing plants attracts these helpful insects.
Cultural practices also manage pest issues. Removing weeds around nasturtiums eliminates hiding spots and alternative food sources for pests.
Preventing Pest Problems
Proactive gardening strategies significantly reduce pest issues. Proper plant spacing, typically 8 to 12 inches apart, promotes good air circulation, deterring pests that thrive in humid conditions and allowing foliage to dry quickly.
Maintaining overall plant health through appropriate watering ensures nasturtiums resist pest attacks. They prefer well-drained soil and do not require overly rich conditions; too much nitrogen can attract aphids.
Companion planting is a powerful preventative measure. Nasturtiums can serve as trap crops, attracting pests like aphids, cabbage worms, whiteflies, and flea beetles away from other plants (plant five to six feet away). Their strong scent can also deter pests suchs as squash bugs and cucumber beetles.
Regular garden clean-up, including removing plant debris, minimizes hiding spots for pests like slugs and snails.