Fungicides are specifically used to control which of the following?

Fungicides are chemical agents specifically designed to target and manage fungal infections in plants. This includes diseases caused by fungi, such as plant rusts, mildews, and blights. These pathogens can cause significant damage to crops and ornamental plants, leading to reduced yields and compromised plant health. By utilizing fungicides, you effectively inhibit the growth and spread of these fungal diseases, protecting the plant and promoting healthier growth.

In contrast, the other options pertain to different types of pests or issues. Insect infestations require insecticides, which are tailored to control insect populations. Weed growth is managed through herbicides, designed to target unwanted plant species. Lastly, nematode populations are addressed with nematicides, which specifically target these microscopic roundworms that can harm plant roots. Each type of pest or disease necessitates a different management strategy, underscoring the importance of using the correct chemical for the specific issue at hand.