Watering according to need with good quality water and fertilizing according to soil test represent the best means of prevention. Toxicity can also result in withering and scorching of foliage. Toxic materials vary in the way they affect plants. Excessive use of fertilizer burns roots and causes root failure described earlier. Certain herbicides may kill roots directly while others translocate to foliage tissue, with these often accumulating on leaf margins and scorching occurs.
Many substances are toxic to plants and their modes of action differ.
Atmospheric toxicity - Certain air pollutants may produce a scorching of the leaf surface. Several described pollutants are capable of causing damage and these are identified in the section on air pollution. Sulfur dioxide causes a scorching around leaf edges initially. This could be confused with damage caused by root failure or toxic substances. Vascular diseases - Plants or trees infected with vascular disease organisms such as Fusarium wilt, Verticillium wilt, or oak wilt may have scorched leaves.