Causes

• Plants require more nitrogen than any other mineral nutrient found in the soil; therefore, nitrogen is often the primary ingredient in inorganic fertilizers. Too much nitrogen, however, forms salts in the soil. These salts draw water out of the plant's roots, dehydrating it. As leaves, stems, flowers and other upper parts of the plant draw their water from the roots, they also get dry, as the sun continues evaporating water from them that they cannot replace with water from the roots.
  
  

Symptoms

• Although fertilizer burn acts on the roots and causes them to become dry and brown, the symptoms you're most likely to notice occurs in the leaves and other above-ground parts of the plant. Leaves wilt, then turn yellow or brown. Leaves become dry and wither and may fall from the plant.
  
  

Treatment

• Fertilizer burn to plant roots may be irreparable and cause long-term damage to or even death of the plant, according to the Cornell University Plant Disease and Diagnostic Clinic. To minimize harmful effects and possibly save your plant, try to leach the excessive nitrogen salts from the soil by slowly trickling water into the soil for 24 to 48 hours, the clinic staff members suggest. Ideally, this moves nitrogen salt beyond the root zone and allows the plant to begin taking in water again. You can repot houseplants into fresh potting soil to reduce the harm caused by overapplication of inorganic nitrogen fertilizer.
  
  

Choosing Fertilizers

• Selecting fertilizers with care also reduces the likelihood of fertilizer burn. Fertilizer burn occurs when too much nitrogen becomes available too quickly. Slow-release inorganic fertilizers release smaller amounts of nitrogen over an extended period of time. While they don't offer the rewarding results of greening and growth seemingly overnight, they also don't carry the risk of burning and damaging your plants and lawn like fast-release fertilizers do.
  
  

Applying Fertilizers

• When applying fast-release inorganic fertilizers, choose a cool, overcast day for fertilizer application. Immediately after application, water in the fertilizer to better distribute it in the soil and keep it from accumulating on plant foliage and around roots. Always follow the instructions on the fertilizer packaging for application rates. When it comes to fertilizer, more is not better.