What are the primary categories of pests in lawn and ornamental pest control?

The primary categories of pests in lawn and ornamental pest control encompass insects, weeds, diseases, and nematodes.

In this context, insects are significant because they can cause direct damage to plants, lawns, and ornamental features by feeding on foliage, roots, and stems or by transmitting diseases. Weeds compete with desired plants for nutrients, water, and light, ultimately reducing the aesthetic and health of lawns and ornamental landscapes. Diseases, typically caused by pathogens like fungi and bacteria, can result in a vast range of problems, affecting the growth and vitality of plants. Nematodes, although microscopic, are important as they can harm roots and affect a plant's ability to take up water and nutrients.

The other choices do not accurately describe the main categories relevant to lawn and ornamental pest control. For instance, while fungi, bacteria, and viruses are important to be aware of, they all group under the broader category of diseases rather than being separate entities as pests. Rodents and birds, although they might affect landscapes in some contexts, are generally not classified as pests in the realm of lawn and ornamental control. Thus, the comprehensive nature of the first option makes it the most fitting representation of the primary pest categories.