FURTHER LINES OF INQUIRY. 45 



INQUIRIES SUGGESTED BY THE FOREGOING EXPERIMENTS. 



Three special lines of inquiry are now under consideration, and will 

 receive undivided attention as soon as the laborious experiments 

 with fertilizers have been completed. These are as follows : 



(1) The period of incubation of the disease prior to its first appear- 

 ance, i. e. 9 the greatest length of time a tree may be aftected before it 

 shows any symptoms of yellows. 



(2) The exact nature of the contagium. 



(3) Its method of spread other than by bud inoculation. 



PART II. PEACH ROSETTE. 

 I. INTRODUCTORY, 



The second part of this report will be devoted to a peculiar disease 

 prevalent in Georgia, and first referred to as probably a Southern vari- 

 ety of peach yellows,* but since described under the name of The Peach 

 Rosette.] 



The disease does not appear to be due to any ordinary fungus, or to 

 insects. In some respects it is quite like peach yellows, but in others 

 it differs very materially. This year additional observations have con- 

 firmed the belief that it is a disease distinct from yellows, and I shall 

 so consider it until proof to the contrary is forthcoming. 



(1) Plants attacked. As stated elsewhere (I. c.), the Rosette attacks 

 many varieties of peaches. None appear to be exempt. It occurs in 

 budded fruit and seedlings. The latter do not escape even when grow- 

 ing in fields and thickets without cultivation. This disease is not con- 

 fined, however, to the peach, but also occurs in plums budded trees 

 and seedlings, cultivated, uncultivated, and wild, and is equally 

 destructive. I have not seen it in varieties of Prunus domestica or in 

 the Mariana, but it occurs in the wild Prunus Chicasa, in the Cumber- 

 land, and Wild Goose, and also in the Japanese varieties known as 

 Kelsey and Botan. Probably the disease is capable of attacking many 

 other sorts, and requires only a suitable opportunity. 



This year in an orchard near Griffin, Georgia, which I know to have 

 been nearly free from disease in 1890, and quite thrifty and well cared 

 for, 1 counted about 40 bad cases of rosette, divided nearly equally 

 between Kelsey and Botan. These trees were 5 or 6 years old, and 

 the loss must have been considerable. 



(2) Characteristics of the disease. As in peach yellows, this disease not 

 infrequently attacks one or two branches only at first, but in a much 

 larger per cent of cases, the whole tree is diseased from the start, and 

 the disease runs its course in a much shorter time. Six months is 

 usually sufficient to destroy a tree, and I have known no cases to last 



* Peach yellows : A preliminary Report, IT. S. Dep. Ag. 1888. 

 t The Journal of Mycology, Vol. 6, No. iv. 



