This disease is caused by a microscopic nematode or true worm,
_Heterodera radicola_,[2] that infests the soft fibrous roots causing
small galls or swellings. When present in sufficient numbers it causes
the death of the roots and the consequent starvation and death of the
tree. It is by no means confined to the fig, but attacks the roots of
many other fruit and ornamental trees and shrubs and is especially
injurious to many garden vegetables and farm crops.[3] This pest thrives
best in moist sandy soils, and is troublesome throughout the entire
coast region.
No effective remedy is known when a tree is once infested, hence the
necessity for planting on land known to be free from the pest, and the
importance of not growing vegetables between the trees that will act as
a nurse crop for the disease.
Neal recommends thorough drainage of the land and the application of
tobacco dust mixed with unleached ashes or lime as the most promising
remedial measures. He advises against the excessive use of ammoniacal
manures as producing a soft, succulent root growth favorable to the
growth of the nematode. (See Bulletin No. 20, previously cited.)
Footnote 2:
G. F. Atkinson, “A preliminary report upon the life history and
metamorphoses of a root-gall nematode (_Heterodera radicola_ (Greeff)
Müll.) and the injuries caused by it upon roots of various
plants.”—Alabama Agr. Exp. Sta. Bul. No. 9.
Footnote 3:
J. C. Neal, in an account of the root-knot disease (Dept. Agr., Div.
Ent., Bul. No. 20) gives a list of over 60 species of plants known to
be infested by it.