The Arizona sentinel., 1899-12-09
THE GROWN GALL.

head or "l1melY HlntS 10 rarm-
 ers," published by the University
 of Arizona Agricultural Experiment
 Station:
 The crown gall is a disease very
 injurious to de2iduous fruit trees.
 particularly so to the almond, april
 cot, peach, plum and nectarine.
 The same, or closely allied gals,
 have been found upon the roots of
 the apple, pear, English walnut.
 grape, raspberry, and number of
 other plants, both cultivated and
 wild.
 The disease may bs readily re- cognized by the large knot-like out. growths which develop at the crown of the plant just beneath the soil or, in older plants, on the roots and root!ets. There is no disease of de. ciduous fruit trees in irrigated re- gions that is as widespread and that causes so much injury to the fruit industry as the crown gall. Not only is it prevalent and rapidly increasing in the irrigated reglons of southwestern United States. but It is becoming one of the most menacing diseases which threaten the fruit industry in practically all of the great fruit centers uf the United States.
 For the past six years have had the crown gall. under observation. and five years ago published pre- limir arY report regarding it, as Bulletin No. 12, of the Arizona Experiment Station. This report was based almost entirely upon ob servations in the field. Two years ago exter sive experiments were be- gun to ascertain the cOmmunicabll ity of tho gall. It is sufficient at this time to state that l have re- peatedly produced the disease by inoculation of young seedlings with | small bits of the gall, in some in dances the gall beginning 60 de 1 velop twenty days after inocula- l lion.
 Again, I have repeatedly pro- i luced the gall on almond seedling- 1 by planting the seeds in sterile soil, and at the time of plating placing d few pieces i'll minced gall in the coil.
 There is TO question regarding the communica bility of this disease; it is contagious. The disease is probably caused by a micro organ isr1 known ss 'lime fungus" the plasmodia of the organism, through irrigation, causing the gall to de- velop. Under certain conditions the plasmodia creep to the surface of the gal and form minute amoe- ba-like bodies which slowly make their way through the damp soil to "ther plants
 No details are here given, as r1p;ct soon to have ready for pub lication, as bulletin for this sta ton, detailed report of the inves- tiga,iOns, describing the cause and 1 nature of the disease, ond how best to deal with it. Knowing the na. turs of the disease, the question is how to eliminate it from the in- tested orchards. The best advice that can give to those intending to plant trees is to get trees from q nursery that is absolutely free from the crown gall. ltis not sufficient to cast aside aside as worthless only those trees with gails upon their roots. Every tree that comes from an infested nursery Is dan gerous, and when snch trees are planted, great chances are taken. If your orchard is already infested with crown gall, you cannot entire Iy get rid of it. All that you can do Is to hold it in check and keep 1 ths gall as much as possible from the crowns of the trees. When it appears on the main stem of tree a few inches below the ground, that is, at the crown, as 1t frequent ly does, particularly on young trees, 1t is almost certain in time. if un- checked, to cause the death of the tree. As this disease only affects the tree at the point where the gall develops and in the adjacent tissue, if the gall be renewed and some thing be applied to the wound tC prevent additional growth, 1t can be held in check, and minimum amount of harm will come to the