Corn borer infestations in a garden can be a serious problem for gardeners, causing significant damage to corn crops. The European corn borer, Ostrinia nubilalis, is a common pest in North America and attacks a variety of crops, including corn, peppers, tomatoes, and beans.
The female corn borer lays its eggs on the leaves and stem of the plant, and the larvae then burrow into the stem, causing the plant to become weakened or even to break. The larvae also feed on the kernels of corn, reducing the yield and quality of the crop. It’s important for gardeners to be aware of the signs of a corn borer infestation and to take measures to prevent and control infestations in order to protect their crops.
Symptoms
- Wilting or yellowing of leaves: As the larvae feed on the inside of the stem, the plant may start to wilt or yellow, indicating that its ability to transport water and nutrients has been compromised.
- Stunted plant growth: The damage caused by the larvae feeding on the stem can also result in stunted plant growth.
- Shrivelled or rotting kernels on the ear of corn: As the larvae feed on the kernels of corn, the kernels may become shrivelled or start to rot.
- Holes in the stem or leaves: As the larvae burrow into the stem and leaves, they may leave behind holes or ragged edges, making the plant more susceptible to disease and further damage.
- Frass (insect excrement) near the base of the plant: Frass may accumulate near the base of the plant, indicating that there are larvae present and feeding on the plant.
- Discoloration and sawdust-like material near the base of the plant: As the larvae burrow into the stem, they may cause discoloration and a sawdust-like material may accumulate near the base of the plant, also indicating their presence.
What is a Corn Borer
- Wingspan of approximately 1.5 cm
- Light-brown to greyish-brown color
- Dark markings on wings, including a thin, white stripe down the center of each wing
- Plump, yellowish-green caterpillar body with dark head
- Small, black spots along the body
- Legs and prolegs (leg-like structures) that aid in crawling and burrowing
- Rounded, dark-colored head capsule for biting and chewing plant material
- Long, cylindrical body with a soft, fleshy appearance.
Treating a Corn Borer Infestation
It may be necessary to use multiple methods to effectively control a corn borer infestation in a garden. For example, crop rotation, hand picking, and pheromone traps can be used together to reduce the build-up of the pest population and reduce the number of eggs laid, while Bt insecticide or chemical insecticides can be used to control a heavy infestation. The best approach will depend on the severity of the infestation and the gardener’s preferences for using chemical or natural methods.
Crop rotation
- Crop rotation is a method of growing crops in different locations each year
- In the case of corn borer infestations, planting corn in a different location each year helps to reduce the build-up of corn borer populations in the soil
- By growing corn in a new location, the previous year’s population of corn borers will not be present to infest the new crop
- Additionally, growing corn in a new location also allows beneficial insects to help control the pests
- Crop rotation is most effective when combined with other methods of pest control, such as hand picking and destruction of infested plants or the use of insecticides
Hand picking and destruction of infested plants
- This method involves regularly inspecting plants for signs of infestation and hand picking and destroying infested plants, along with any egg masses
- This method is effective for small gardens or for controlling a minor infestation
- It is important to regularly inspect the plants and destroy any infested ones, as this will help to reduce the number of corn borers that are able to mature and lay eggs
- This method may not be sufficient for controlling a heavy infestation, but it can be used in combination with other methods, such as crop rotation or the use of insecticides
Use of insecticides
- Chemical insecticides can be applied as a spray to the leaves and stems of the plants
- Insecticides should be applied at the correct timing and rate, according to the label instructions
- This method can be effective for controlling a heavy infestation, but it may also have negative effects on beneficial insects and the environment
- It is important to follow the label instructions and not apply insecticides in excess, as this can harm the plants and the environment
- This method can be used in combination with other methods, such as crop rotation or hand picking and destruction of infested plants, for a more effective control of the pest population
Use of Bacillus thuringiensis (Bt) insecticide
- Bt insecticide is a natural bacterium that is toxic to certain insects, including the corn borer
- Bt insecticide can be applied as a spray to the leaves and stems of the plants
- This method can be effective for controlling a moderate infestation, while being less harmful to the environment and beneficial insects compared to chemical insecticides
- Bt insecticide works by being ingested by the larvae and causing digestive disruption, leading to death
- This method can be used in combination with other methods, such as crop rotation or hand picking and destruction of infested plants, for a more effective control of the pest population
Use of pheromone traps
- Pheromone traps can be used to trap male corn borers and reduce the number of mating opportunities for the females
- Pheromone traps should be placed in the garden before the adult moths begin to emerge
- The traps contain a pheromone lure that attracts the male moths, which are then trapped in the sticky interior of the trap
- This method can help to reduce the number of eggs laid, but it may not be sufficient for controlling a heavy infestation
- Pheromone traps can be used in combination with other methods, such as crop rotation or hand picking and destruction of infested plants, for a more effective control of the pest population.