Which types of fungi do Metalaxyl and Mefenoxam specifically target?

Metalaxyl and Mefenoxam are systemic fungicides that specifically target water molds, commonly referred to as Oomycetes. These types of fungi are primarily responsible for issues like seed rot and damping-off diseases, which can lead to significant losses in crops by affecting seedlings when they are most vulnerable. These pathogens thrive in moist conditions, leading to rotting of seeds and damping off, where seedlings fail to emerge or establish due to infection.

The action of Metalaxyl and Mefenoxam interrupts the growth and reproduction of these water molds, thereby preventing the diseases associated with them. Their effectiveness lies in their ability to penetrate plant tissue and provide protection from infection once applied to the seed or soil.

Choosing this response highlights an understanding of the specific diseases that these fungicides address, illustrating the importance of targeted treatments in managing plant health. The other types of fungi listed in the other choices do not represent the primary targets of Metalaxyl and Mefenoxam, making this answer not only correct but also crucial for effective seed treatment strategies.