Pecan Diseases and Pests and Their Control

MP-313 NOVEMBER 1958
TEXAS AGRICULTURAL EXPERIMENT STATION ... TEXAS AGRICULTURAL EXTENSION SERVICE College Station, Texas
David W. Rosberg and D. R. King
Respectively, associate professor, Department of Plant Physiology and Pathology, and associate professor, Department of Entomology.
The pecan tree must be protected from attack by the many destructive diseases and insects that affect it to produce a bountiful nut crop.
The diseases that affect the pecan, especially those caused by fungi, are rapidly spread throughout the trees in an orchard in the early spring. During this season of frequent rains, the spores of the disease fungi germinate and invade the young tender tissues of the shoots, leaves and nuts. Under conditions of prolonged damp weather, when the humidity remains high, the disease organisms reproduce at a rapid rate and cause severe shedding of leaves and nuts.
Pecans are attacked by more than 20 species of insects that cause damage to leaves, nuts, twigs, buds, branches and even the bark. The development of commercial pecan acreages has provided ideal conditions for the increase in severity of both disease and insect damage because of the abundant food supply in a concentrated planting of pecans. In its natural habitat the pecan is less subject to the devastations of diseases and insects.
The many destructive insects and diseases must be controlled for successful pecan production. The pecan grower must also understand the nature and habits of the various disease and insect pests that threaten his crop and use certain cultural practices which help to reduce damage from diseases and insects.
The diseases which affect the pecan are of four different types: namely fungus, bacterial, virus and physiological. The fungus diseases, the most numerous and widespread, are caused by small microscopic molds. Approximately 12 different fungus organisms cause harmful diseases of the pecan.
The bacterial disease organisms, unlike the disease producing fungi, are single celled and can be seen only under a microscope. Bacterial diseases are fewer and of less economic importance than fungus diseases.