Aphids are small, soft-bodied insects that cluster on the undersides of sweet pea leaves and stems. They pierce plant tissues to suck sap, causing leaves to curl, yellow, and stunt growth. Aphids also excrete honeydew, which attracts ants and promotes sooty mold growth. To control aphids, spray plants with a strong jet of water to dislodge them or apply insecticidal soap. Introducing natural predators like ladybugs can also help reduce aphid populations.
Spider mites are tiny arachnids that thrive in hot, dry conditions. They feed on sweet pea leaves, causing stippling, yellowing, and eventual leaf drop. Severe infestations may produce fine webbing on the plant. To combat spider mites, increase humidity around plants by misting them regularly. Use miticides or neem oil for severe cases, and remove heavily infested leaves to prevent spread.
Slugs and snails chew irregular holes in sweet pea leaves, especially in damp conditions. Young seedlings are particularly vulnerable. To deter these pests, create barriers like copper tape or diatomaceous earth around plants. Handpick slugs and snails at night or use beer traps to lure and drown them. Organic slug pellets can also be effective if used sparingly.
Thrips are slender, tiny insects that scrape sweet pea leaves and flowers, leaving silvery streaks and distorted growth. They also spread viruses like tomato spotted wilt virus. Control thrips by removing weeds and debris where they hide. Apply spinosad or neem oil, and use reflective mulch to repel them. Blue sticky traps can help monitor and reduce their numbers.
Caterpillars, such as those of the pea moth, feed on sweet pea foliage and pods, causing significant damage. Look for chewed leaves and frass (droppings). Handpick caterpillars when possible, or use Bacillus thuringiensis (Bt), a natural bacterial spray that targets them without harming beneficial insects. Encourage birds and predatory wasps to help control caterpillar populations.
Whiteflies are small, winged insects that congregate on the undersides of sweet pea leaves, sucking sap and weakening the plant. They excrete honeydew, leading to sooty mold. Control whiteflies with yellow sticky traps or by spraying plants with insecticidal soap or neem oil. Introduce natural enemies like parasitic wasps for long-term management.
Leaf miners are larvae that tunnel inside sweet pea leaves, creating winding, white trails. While they rarely kill plants, they reduce photosynthesis and aesthetic appeal. Remove and destroy infested leaves to break their life cycle. Use spinosad or parasitic wasps for biological control. Avoid broad-spectrum insecticides, which harm beneficial insects.
Powdery mildew appears as white, powdery spots on sweet pea leaves, stems, and flowers, often in humid conditions. Improve air circulation by spacing plants properly and avoid overhead watering. Apply fungicides like sulfur or potassium bicarbonate at the first sign of infection. Resistant sweet pea varieties can also help prevent outbreaks.
Root-knot nematodes are microscopic worms that attack sweet pea roots, causing galls, stunted growth, and yellowing leaves. Rotate crops annually and plant nematode-resistant varieties. Solarize soil before planting to kill nematodes, or apply organic amendments like compost to boost beneficial soil microbes that suppress them.
