Low to moderate numbers are usually not harmful to crops. Severe infestation can cause leaves and shoots to curl, wilt or yellow and stunt plant growth. A general decline in plant vigor will be noticed. Aphids produce honeydew that can cause an additional infection by opportunistic fungi, indicated by the development of mold on the leaves. The honeydew also attracts ants. Even small numbers of aphids can transmit viruses from plant to plant in a persistent way.
Aphids are small, soft-bodied insects with long legs and antennae. Their size ranges from 0.5 to 2 mm and the color of their body can be yellow, brown, red or black, depending on the species. Their aspect ranges from the wingless varieties, that are generally predominant, to the winged, waxy or woolly types.Optimal conditions for their growth are dry and warm climates. They usually settle and feed in clusters on the underside of well-fed young leaves and shoot tips. They use their long mouth parts to pierce tender plant tissues and suck out fluids. After an initial invasion in late spring or early summer, the aphid population usually diminishes naturally due to natural enemies. Several species carry plant viruses that can lead to the development of other diseases.
In case of mild infestation, use an insecticidal soap solution or solution based on plant oils, e.g. neem oil (3 ml/l). Aphids are also very susceptible to fungal diseases when it is humid. A spray of water on affected plants can also remove them.
Always consider an integrated approach with preventive measures together with biological treatments if available. Be aware that the use of chemical pesticides can cause aphids to become resistant to those that are used. Stem application with flonicamid and water (1:20) ratio at 30, 45, 60 days after sowing (DAS) can be planned. Fipronil 2 ml or thiamethoxam (0.2 g) or flonicamid (0.3 g) or acetamiprid (0.2 per liter of water) can also be used. However, these chemicals can have negative impacts on predators, parasitoids, and pollinators.
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