17 
9 and 15 had no effect visible. Nos. 0, 7, 10, and 14 made a better 
growth than Nos. 17-20. Root-knot was present on all but Nos. 13, 
14, and 20. 
On still larger trees, applied at the rate of 27 pounds to the tree, Nos. 
6, 13, 14, 17, 18, 19, and 20 gave good results, especially and 17, G and 
18, 6 and 19. These mixtures seemed to promote a vigorous growth of 
healthy roots, and Nos. G and 20, each 27 pounds to the tree, well mixed 
with the surface soil, appears to be as near a preventive of the " knot" 
as anything I have tried. 
I tried the bisulphide of carbon without any effect other than the death 
of the trees, some fifty or more, and the kerosene emulsion to saturation 
of the surface soil produced asimilar result, and in view of the expense 
and labor involved I did not repeat the experiment. (Note 7.) 
A number of the prepared artificial fertilizers were tried ; those con- 
taining ammonia, guano, bone, and fish produced a rapid growth, soft 
and easily attacked by the Anguillula3. 
In a field near my place, heavily fertilized with a bone and potash 
compound, the roots of the pea nut became masses of knotty roots, the 
worst cases of the disease I ever saw, and peach-trees growing in that 
field are ruined. 
I have found nothing of value when applied to old bearing fruit trees, 
if badly affected, as any insecticide capable of absorption by the roots 
invariably has killed the trees when used to the amount of ^ the 
weight of the surface soil, 1 foot in depth and the area of the circle 
filled by the roots. Alkaline mixtures, 20 to 40 pounds to each tree, or 
caustic lime, kainite, muriate and sulphate potash or wood ashes, used 
several years in succession, have come nearest a cure, destroying no 
doubt many free worms, and inducing a vigorous, tough growth of roots, 
more difficult of penetration, and possibly rendering the sap in some 
way obnoxious. (Note 8.) 
The addition of tobacco dust in large quantities supplies nitrogen, 
and makes a very vigorous growth of roots and limbs. It also seems to 
have considerable preventive effect on the worms. Experiments con- 
ducted by one^ of our market gardeners has convinced him that the 
mixture of tobacco dust and muriate of potash in old fields in great 
measure prevents the ravages of the Anguillula in Okra, Cabbage, and 
Egg-plant, and he has adopted this as a standard fertilizer for all his 
products. I have seen his use of this, and am nearly prepared to sus- 
tain his views. Kainite is no doubt fully as good, but further experi- 
menting is necessary. 
Another series of experiments was made upon plants to determine 
the time and degree of infection. 
No. 21. Sterilized pots with T ^ cubic foot of sterile soil, in which four 
cow-peas were planted at various depths, one-half inch, three-fourths 
inch, and 1 inch, were covered L inch with infected earth and kept wa- 
tered. The results showed infection of the roots in about the same ra- 
23495—Bull, 20 2 
