Common Signs and Symptoms of Unhealthy Plants

Plant symptoms may be caused by biotic (living organisms) 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. Insects, mites, fungi, bacteria, nematodes, viruses, parasitic higher plants, protozoa, and grazing or browsing animals are all examples of biotic agents that damage plants.