because of its inherent
toxicity to the non-cutinzed root surfaces.

5. Laboratory and field tests have shown juglone to be an excellent
fungicide

LITERATURE CITED

1. Bernthsen, A. and A. Semper Ueber die Constitution des Juglons
und seine Synthese aus Naphtalin. Ber. d. deutsch. Chem. Gesellsch.
20: 934-941. 1887.

2. Brissemoret et Michaud Sur une nouvelle classe de medicaments de
la peau; les quinones peroxydes. Jour. pharm. et chim. 7e ser.
16:283-285. 1917.

3. Brown, Babette I. Injurious influence of bark of black walnut on
seedlings of tomato and alfalfa. Northern Nut Growers' Assn., Proc.
1942:97-102. 1943,

4. Combes, R. Sur un procede de preparation et de purification des
derives oxyanthraquinoniques et oxynapthoquinoniques en general, du
juglon et de l'emodine en particulier. Bull. soc. chim. 4c ser. 1:
800-816. 1907.

5. Cook, Mel T. Wilting caused by walnut trees. Phytopathology
11:346. 1921.

6. Davis, Everett. The toxic principle of _Juglans nigra_ as
identified with synthetic juglone, and its toxic effects on tomato
and alfalfa plants. Amer. Jour. Bot. 15: 620. 1928.

7. Greene, K.W. The toxic (?) effect of the black walnut: Northern
Nut Growers' Assn., Proc. 1929: 152-156. 1930.

8. Jones, L. R. and W. J. Morse The shrubby cinquefoil as a weed.
16th Ann. Rpt, Vt, Agr. Expt. Sta. 188-190. 1902-03.

9. MacDaniels, L. H. and W. C. Muenscher Black walnut toxicity.
Northern Nut Growers' Assn., Proc. 1940 172-179. 1941.

10. Massey, A. B. Antagonism of the walnuts (_Juglans nigra I._ and
_J. cinerea_.) in certain plant associations. Phytopathology 15:
773-784. 1925.

11. Pirone, P. P. The detrimental effect of walnut to Rhododendrons
and other ornamentals. Nursery Disease Notes 11; 1-4. 1938.

12. Plinius Secundus, C. The historie of the world. English
translation by P. Holland, A. Islip, London. 1601.

13. Schneiderhan, F. J. The black walnut (_Juglans nigra L._) as a
cause of death to apple trees. Phytopathology 17: 529-540. 1927.

Possible Black Walnut Toxicity on Tomato and Cabbage

_By OTTO A. REINKING

New York State Agricultural Experiment Station_

The toxicity or antagonism of black walnut roots and those of certain
other plants has been a controversial question. L. H. MacDaniels and W.
C. Muenscher i