Which term describes a substance that is harmful or toxic to plants?

The term that describes a substance that is harmful or toxic to plants is "phytotoxic." Phytotoxicity refers to the capacity of a chemical, often a pesticide or herbicide, to cause damage to plant tissues, which can lead to symptoms such as leaf burn, stunting, or even plant death. This is a critical concept in turf and ornamental management, as understanding the phytotoxic effects of various substances helps ensure that treatments do not inadvertently harm desirable plants while managing weeds.

In contrast, herbicidal specifically refers to substances designed to kill or inhibit the growth of unwanted plants, particularly weeds. While these chemicals can be phytotoxic, not all phytotoxic substances are herbicidal.

The term invasive refers to non-native plants that spread aggressively and can disrupt local ecosystems, but it does not pertain to toxicity. Beneficial substances or organisms, such as certain fertilizers or pest predators, contribute positively to plant health and are the opposite of harmful substances. Recognizing the distinction among these terms is essential for effective weed management and maintaining the health of ornamental and turf landscapes.