The best way to defend against pest invasion in annual gardens is to start planting beds off right – from amending the soil and choosing healthy plants to proper planting technique. Unfortunately, sometimes our best efforts are no match for “bad bugs.”
Damage from pest infestation is easily noticed upon inspection. Make every effort to identify the specific pest responsible for the damage before attempting control, then treat with measures specifically tailored to that pest.
Photo Credit: ©2000 Dolezal Publishing/Tim Butler
Aphids are sucking insects that feed on plant juices. As a first defense, blast them off your plants with a strong stream of water from the garden hose.
Photo Credit: ©2000 Dolezal Publishing/John M. Rickard
Is your flower garden under attack? Use this guide to help identify common pest-problem symptoms on annuals, learn which pest is likely causing the issue and discover some remedies to try.
Symptom: Curled, puckered or twisted leaves, often with a sticky coating and/or black, sooty appearance. Stunted or deformed blooms on new growth.
Cause: Aphids. Look for tiny, green-yellow, reddish, brown or gray wingless insects clustered on buds, shoots and undersides of leaves.
Remedies: Spray with a strong stream of water from the garden hose, try insecticidal soap or remove and discard plants.
Symptom: Seedlings cut off at ground level.
Cause: Cutworms. Look for smooth, gray-brown, wormlike moth larvae under plant debris or just below the soil surface.
Remedies: Install cardboard collars (like toilet paper tubes) around plant stems and sink them 2 inches into the soil.
Symptom: Holes in leaves and flowers. Stems may be reduced to skeletons.
Cause: Japanese beetles. Look for half-inch-long insects with copper-colored bodies and green heads.
Remedies: Handpick, then kill the pests by either stomping on them or dropping them in a bucket of soapy water. Spray with insecticidal soap near soil. If that’s ineffective in controlling the infestation, spray insects with pyrethrin or rotenone, but only as a last resort.
Symptom: Leaves stippled with yellow; may be curled, dry and withered, with webs on tips and undersides. Plant may be stunted.
Cause: Spider mites. Look for reddish, green or yellow, pinhead-sized insects. Prevalent in hot, dry areas. (Lantana, verbena and sweetpea are particularly susceptible.)
Remedies: Spray with a steady stream of water or try insecticidal soap. If both are ineffective, spray with Neem or pyrethrin, but only as a last resort.
Symptom: Yellow leaves and stunted, sticky plants. When plant is shaken, a cloud of white insects may fly up.
Cause: Whiteflies. Look for minuscule, white, mothlike insects on the undersides of leaves.
Remedies: Catch with sticky cards, or try insecticidal soap. Horticultural oil may also work. If infestation continues, spray with pyrethrin, but only as a last resort.
Symptom: Off-color, stunted plants. Stems and leaves may have white, cottony clusters.
Cause: Mealybugs. Look for white, oval-shaped insects on leaves, leaf axils and shoots.
Remedies: Remove leaves and kill remaining pests with cotton swabs dipped in alcohol or spray with insecticidal soap. Horticultural oil or Neem may also work.
Symptom: Leaves with brown or black spots. Roots and shoots may be deformed.
Cause: Plant bugs. Look for greenish-yellow insects 1/4 an inch long.
Remedies: Handpick or spray with insecticidal soap. If infestation is severe, spray affected areas with pyrethrin or rotenone as a last resort.
Symptom: Leaves or stems are brown or speckled with white and may be gummy or deformed.
Cause: Thrips. Look for tiny yellow or black flies.
Remedies: Spray with water or try insecticidal soap. Ladybugs can also help.
Symptom: White trails on foliage. Papery yellow or brown blotches on leaves.
Cause: Leaf miners. Look for small, pale larvae and tiny, green or black insects.
Remedies: Remove infected leaves. Encourage beneficial insects, especially ladybugs or lacewings, to visit your garden. Remove infected leaves. Neem may also help.
Symptom: Discolored leaves and plants. Leaves are puckered, curled or twisted.
Cause: Leaf hoppers. Look for small, green, wedge-shaped insects.
Remedies: Trap with sticky traps, dust with diatomaceous earth, spray with insecticidal soap or try horticultural oil.
Symptom: Chewed leaves. Silvery slime trails are left on foliage and stems or on the ground nearby.
Cause: Slugs and snails. Look under rocks, boards and other hiding places for adult mollusks.
Remedies: Handpick after dark (don’t forget your flashlight), when snails and slugs emerge. Use copper foil barriers around the bases of containers, set out trays filled with beer or use commercial baits and gels.
Symptom: Chewed blossoms and petals, especially those with soft, fleshy parts.
Cause: Earwigs. Look for brown to black pests with sharp pincers extending from the rear part of their bodies.
Remedies: Set out crumpled or rolled newspaper – earwigs will hide inside, then you can collect and destroy. Apply bait or spray with solutions containing Sevin® as a last resort.
