Common Signs and Symptoms of Unhealthy Plants Plants symptoms may be caused by biotic (living organism) or abiotic (nonliving) agents. Many abiotic factors can cause symptoms in a landscape or garden. These factors include nutrient imbalances, drought or excess soil moisture, limited light, reduced oxygen availability, air pollution, soil pH extremes, pesticide toxicity, compaction, cultural practices, mechanical damage, and low or high temperatures. Stunting: Hindering of normal growth or overall development of a plant. Insects, mites, fungi, bacteria, nematodes, viruses, parasitic…