There are weeping forms of many ornamental plants. Site conditions such as compaction or poor drainage may cause the death of roots, leading to problems with the foliage, and the eventual death of the plants. Under application of fertilizer can result in plants with yellow leaves, over application of fertilizer can kill roots. There are many other site-related problems that result in poor plant performance that can be blamed on the use of herbicides. There are cultural or physical problems that can mimic the injury caused by herbicides.
Nutrient deficiencies can cause discolored or stunted foliage.
Disease problems can cause browning of some leaves that can mimic the damage caused by contact herbicides. Insect and some disease problems can cause leaf curling that resembles the injury caused by some herbicides. Frost can kill young, tender foliage and stem tips, or cause bark splitting. Most herbicides have distinctive injury symptoms that can be used to determine whether or not the injury observed could have been caused by the herbicide. If the injury symptom is a yellowing of the foliage, it could not have been caused by a contact herbicide.