In what ways do pests cause injury to plants?

Pests can significantly harm plants mainly by damaging various plant parts and competing for essential nutrients. When pests such as insects or nematodes infest a plant, they may feed on leaves, stems, roots, or fruits, leading to physical damage. This can result in reduced photosynthesis, weakened structural integrity, stunted growth, and reduced yields. Moreover, pests may also compete for vital nutrients and water resources, extracting these essentials from the plant, which further exacerbates the plant's stress and decline. This disruption of the plant's nutrient uptake can hinder its ability to thrive, making it more susceptible to diseases and other environmental stresses.

The other options do not accurately describe the impact pests have on plants. Increased water availability is not a factor influenced by pests; rather, they can create conditions leading to water stress. Promoting healthy growth is contrary to the nature of pests, as their presence typically results in stress or damage instead of enhancement. Lastly, pests do not enhance soil properties; instead, they may lead to a decline in soil health as plants become weakened and less capable of supporting beneficial soil organisms.