58 .1 " Wither Tip " of PInm Trees 



4. Inoculation of plum leaves with pure cultures of a strain of the 

 fungus obtained from a withered twig gave negative results. 



5. Inoculation of the stigmas of phun flowers resulted in every case 

 in infection and C()nse(|uent death of the flowers; in some instances the 

 infection not only killed the flowering spur but invaded the branch and 

 formed a canker, 



6. Inoculation of the fruit gave negative results on uninjured plums, 

 • but when the conidia were applied to wounds they produced a "brown 



rot"' which rapidly extended through the fruit and infected other plums 

 which were in contact with those primarily inoculated. 



7. Inoculation of apple flowers with conidia of the "wither tip" 

 strain resulted in the death of the inoculated flowers only; fihese fell off 

 and infection extended no further. On the other hand inoculation of 

 apple flowers with a "blossom wilt" strain from an apple tree not only 

 caused infection of the treated flowers but the fungus extended also into 

 the tissues of the spurs and killed all the flowers and leaves borne by 

 these spurs. 



8. The two strains of Monilia cinerea used in these experiments are 

 indistinguishable morphologically and, since they are dissimilar in their 

 powers of causing infection of the apple blossom, are to be considered as 

 "biologic forms"' or physiological strains. They can be distinguished by 

 applying cultural and biochemical methods. 



9. Spraying as a means of controlling the "Wither Tip" disease is 

 not to be recommended. All diseased twigs and fruit affected with 

 "brown rot"' should be removed from the trees, otherwise they will 

 prove sources of infection for the flowers and fruit of the following 

 season. 



BIBLIOGRAPHY. 



(1) Adkrhold, R. Die Monilia (6'r('e?-o///i(V/)-KrankfK'iton unscror Obstbauine uiul 

 ihre Bfkiinipfiinc;. Kdi.'^er!. Biol. A».'<l. f. Land- ii. Foi-.^tirirl.^chafl. Flughlatt 

 Nr. 14, Sept. 1905. 



(2) u. RuHLANi), W. Zur KenntnisdtT 01).stl)auin-Skl(>rotiiii(>n. Arbeit, hiol. 



All. Land und Forsl. KaiserJ. (lesundheilsa^nle, A, 1905, pp. 427-442. 



(3) Alsberc), C. L. and Black, O. K. < 'ondiljution to the study of niai/.c deteriora- 



tion. U.S. Dep. Agric. Bvr. Plaiil lndu,slry. Bull. 270. 191:}. 



(4) DucoAR, B. M. Fungom DiseaseH oj Planls. Boston, U.S.A., 1909. 



(5) Eyrk, J. V. and Salmon, E. S. The Fungicidal Proportie.^ of Certain Spray- 



Fluids, ./onrn. A(/rir. Science, vol. vn. Part iv, April 1910. 



(G) A new Fungicide ior usf against American Cooscbcrry-.Atiiilew . Jviini. 



Board of Ayrir. vol. xxn, Xo. II, Feb. 191(). 



