Verticillium Wilt

• This fungal disease attacks a range of woody trees and shrubs, including Texas ash. Verticillium wilt spreads from the roots of dead trees and is most likely to damage specimens already stressed from heat or drought. Leaves curl, turn yellow or red between the veins, wilt, eventually die and fall off. Verticillium wilt also kills entire branches and discolors sapwood. This condition kills the tree in time. Verticillium wilt cannot be treated once an infection begins. Maintaining good cultural conditions and avoiding damage to the roots and lower trunk prevents this disease.
  
  

Aphids

• Aphids are small insects that drink sap from leaves, stems and other soft parts of plants. They come in a range of species and attack many plant and tree types. When these insects feed on Texas ash leaves, the scar tissue they produce causes the leaves to curl and distort. The leaves also turn yellow and become stunted. Aphids produce a sweet substance called honeydew, which encourages fungi such as sooty mold. These insects are unlikely to kill Texas ash trees, but can weaken them to other diseases. Encouraging their natural enemies and by spraying small trees with neem oil or insecticidal soap controls aphids.
  
  

Leaf Rollers

• Leaf rollers are the larval form of medium-sized moths and feed on the leaves of oak, ash, birch, maple, poplar and other trees. These insects chew the edges of new leaves, causing them to become ragged looking. They also roll leaves up and tie them with silk, creating a hiding place for themselves. Severely damaged leaves may fall off the tree. In cases of serious infestations, these insects can defoliate the tree. The University of California - Davis recommends controlling leaf rollers in Texas ash by using Bacillus thuringiensis, a bacterial-control technique that kills caterpillars but not beneficial insects. Use conventional pesticides as a last resort.
  
  

Ash Leaf Rust

• Ash leaf rust is a fungal condition common in the Northeastern United States. This condition affects white, green and black ash, as well as Texas ash. This disease spreads via airborne spores and infects emerging leaves, causing galls on green twigs and dark or reddish spots on leaflets. The spots cause the leaf to distort and curl in time. Serious cases cause the tree to look burnt or lose its leaves. Serious cases can weaken trees to winter damage and other diseases, but most ash rust does not kill the host. Prevent severe infections by keeping trees in good conditions with regular irrigation and fertilizing. Apply fungicidal sprays as needed.