Everything you need to know about fungicides

Fungicides are indispensable tools in disease management, offering protection against fungal pathogens and ensuring the health and productivity of crops and plants. In this guide, Zunel van Eeden aims to improve producers’ understanding of the different types of fungicides, their various modes of action, and more.

- Zunel van Eeden

Fungal diseases represent a persistent threat to crops, causing significant economic losses and impacting food security. They occur when fungal spores germinate and penetrate a plant. The fungus grows in, on and through the plant and can reproduce by releasing spores that can lead to secondary infections.

Leonard Oberholzer, corn go-to-market lead for Africa at Bayer Crop Science, told Farmer's Weekly that for fungi to infect the crop, the fungi (pathogen), crop (host) and a favourable environment must be present at the same time. This phenomenon is known as the disease triangle.

To reduce the probability of fungal infections, integrated pest management (IPM) is handy to eliminate the host, manipulate the environment or reduce pathogens to help prevent their future spread. An example is alternating between crops (crop rotation), planting resistant cultivars, and managing the amount of crop residue left on the soil before planting a new crop.

CONTACT VS SYSTEMIC

Fungicides are broadly categorised based on their mode of action (MOA), encompassing two main types: contact and systemic. Contact fungicides primarily act on the surface of plant tissues, forming a protective barrier that inhibits fungal spore germination and growth. They do not penetrate plant tissues and instead provide localised protection, making them effective against foliar diseases and superficial infections. They offer immediate yet temporary protection as they can be washed away by rainfall or degraded by sunlight.