Tobacco

Aphids

Aphis

Insect

5 mins to read

In a Nutshell

  • Curled and deformed leaves.
  • Small insects under the leaves and shoots.
  • Stunted growth.

Can also be found in

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Tobacco

Symptoms

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.

Recommendations

Organic Control

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.

Chemical Control

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.

What caused it?

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.


Preventive Measures

  • Maintain a high number of different varieties of plants around fields.
  • Remove plant debris from previous cultures.
  • Use reflective mulches to repel invading populations of aphids.
  • Monitor fields regularly to assess the incidence of a disease or pest and determine their severity.
  • Remove infected plant parts.
  • Check weeds in and around the fields.
  • Do not over-water or over-fertilize.
  • Control ant populations that protect aphids with sticky bands.
  • Prune the branches of your trees or remove the bottom leaves of your plants to favor the ventilation of the canopy.
  • If possible, use nets to protect the plants.
  • Control insecticide use in order not to affect beneficial insects.

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