Potato Growing Guide: Wireworms

Symptoms of Wireworm Contamination

• Presence of bites, holes and galleries in the tubers : Wireworm larvae attack the tubers directly, creating visible galleries that can facilitate the entry of pathogens.
• Degradation in late summer and spring : The damage is more visible during these periods, corresponding to times of intense larval activity.
• Loss of market value : An infested harvest sees its value decrease significantly, especially in the case of heavy infestation, which can lead to the downgrading or non-marketing of batches.

In the face of these signs, it is essential to adopt strict management measures to prevent the proliferation of wireworms and protect the harvest.

Ways to Prevent Wireworms

Long Crop Rotation

A rotation of at least three years is recommended to disrupt the wireworm's life cycle and limit their population. Ideally, a rotation of four to five years would be recommended, thus avoiding immediate replanting of potatoes or crops that encourage wireworm development.

Avoid Wireworm-Friendly Crops

Previous crops such as permanent grassland, clover, alfalfa, and flax are favorable environments for wireworms to thrive. It is therefore best to avoid planting potatoes after these crops. Instead, opt for rotations with crops that are less attractive to wireworms, such as corn, cereals, rapeseed, or beets.

Regular Tillage

Plowing and the use of a rotary harrow reduce the number of larvae by exposing them to natural predators and disrupting their environment. This tillage, in addition to aerating and optimizing the soil structure, helps reduce the wireworm population.

Choice of Resistant Varieties

Some potato varieties are more resistant to wireworm attacks , or are less appealing to these pests. It may be a good idea to check with specialist suppliers, such as Patativerse, for the most resistant varieties.

Early Harvest and Regrowth Management

Early harvesting helps minimize wireworm damage at the end of the crop cycle, when wireworm activity is at its peak. In addition, proper management of volunteer potato growth is essential, as volunteer growth can serve as a refuge for wireworm larvae, increasing their numbers for the following season.

Ways to Control Wireworms

Preventive Insecticide Treatment

Applying insecticide treatments to the soil before planting remains one of the only authorized chemical options for controlling wireworms. These treatments can significantly reduce the larvae population even before the start of cultivation, although their use must comply with environmental and safety standards.

Biological "Attract and Kill" Method

The "Attract and Kill" technique involves luring wireworm larvae to traps containing entomopathogenic fungi, which infect and kill the larvae. This method, while innovative, requires regular monitoring and the well-timed installation of traps to maximize its effectiveness.

Bait Plants and Natural Barriers

Planting bait plants such as rows of barley can also deter wireworms from potato crops. These plants attract the larvae, thus limiting damage to the tubers. This technique, while simple, requires some expertise to manage the placement and maintenance of bait plants without affecting overall yield.

Application of Entomopathogenic Fungi

Entomopathogenic fungi are biological agents that attack insects. Their application in infected fields helps reduce wireworm populations in an environmentally friendly manner, limiting environmental impacts while maintaining the natural balance of the soil.

Surveillance by Trapping

Setting "FURLAN" traps with specific pheromones from April onwards allows wireworm populations to be monitored and infestations to be detected at an early stage. This proactive monitoring allows for rapid response to any increase in the population and appropriate management measures to be taken.

Additional Information on Wireworms and Their Management

Wireworm management requires an integrated, long-term approach. Curative treatments are often limited in effectiveness once an infestation has taken hold. Therefore, it is essential to prioritize prevention and combine control methods to achieve the best results. Wireworms thrive particularly in clay-limestone soils and permanent grassland fields, so it is important to consider soil and climate conditions when planning crops.