Which statement correctly describes the risk associated with systemic fungicides?

Which statement correctly describes the risk associated with systemic fungicides?

• A. Pathogens can develop resistance to them
• B. They never lose effectiveness
• C. They are always safe for all plants
• D. They work instantly in every case

Answer: (A)

Systemic fungicides move through the plant, reaching and protecting new growth. Because they provide internal, ongoing exposure to pathogens, they can impose strong selective pressure. If the same product is used repeatedly or at suboptimal doses, some pathogens may survive and pass on resistance traits to their offspring. Over time, the population shifts toward those resistant individuals, making the fungicide less effective. That’s why the risk described is that pathogens can develop resistance to systemic fungicides. Fungicides don’t stay perfectly effective forever, and relying on them alone without rotation or integrated practices can lead to reduced performance due to resistance. They aren’t safe for every plant in every situation, and they don’t act instantly in all cases—there’s a lag while they are absorbed, translocated, and reach the target tissues, and results can vary with environmental conditions and disease pressure.

Systemic fungicides move through the plant, reaching and protecting new growth. Because they provide internal, ongoing exposure to pathogens, they can impose strong selective pressure. If the same product is used repeatedly or at suboptimal doses, some pathogens may survive and pass on resistance traits to their offspring. Over time, the population shifts toward those resistant individuals, making the fungicide less effective. That’s why the risk described is that pathogens can develop resistance to systemic fungicides.

Fungicides don’t stay perfectly effective forever, and relying on them alone without rotation or integrated practices can lead to reduced performance due to resistance. They aren’t safe for every plant in every situation, and they don’t act instantly in all cases—there’s a lag while they are absorbed, translocated, and reach the target tissues, and results can vary with environmental conditions and disease pressure.