126 Journal of Agricultural Research voi. xii, no. 3 



a particular size was hardly sufficient to form a basis for conclusions, 

 but it is evident that the disease was worse on the large apples than on 

 the small, and that with the exception of one or two cases where there 

 were but few apples heavy irrigation increased the amount of disease 

 on the medium-sized as well as on the large fruit. 



DISCUSSION OF RESULTS OF BiTTER-PiT EXPERIMENTS 



The results of the various experiments have been uniformly consistent 

 in showing that heavy irrigation favors the development of bitter-pit. 

 Heavy irrigation throughout the season has given less of the disease 

 than medium irrigation followed by heavy, and light irrigation through- 

 out the season has resulted in more bitter-pit than heavy irrigation 

 followed by light. Heavy irrigation the first half of the season caused 

 the trees to develop a more luxuriant foliage and probably produced a 

 lower concentration of cell sap in the apples, both of which facts would 

 tend to make the fruit less susceptible to the forcing efifects of late irriga- 

 tion. The amount of irrigation in August and September has apparently 

 largely determined the amount of disease. 



Sudden changes in the amount of soil water do not appear to have 

 had any effect upon the amount of disease. No evidence has been 

 found that bitter-pit is brought about by a rupture or bursting of the 

 cells. 



Large apples have been more susceptible to bitter-pit than small 

 ones, but the increase in the disease from heavy irrigation has been 

 almost as great on the small and medium sized fruit as on the large. 

 This fact is brought out in Tables I, V, VI, and IX, and in a particularly 

 striking manner in figure 6. Apparently apples are not susceptible to 

 bitter-pit merely because they are large, but rather because of condi- 

 tions that may sometimes accompany an increased growth. 



The results as a whole point to the harmful effects of heavy late irri- 

 gation regardless of the size of the fruit. In looking for the final cause 

 of the disease not only the direct growth -forcing effects of the water 

 should be considered but also the effects of the excess water upon the 

 soil flora and soil solutes. This subject will be more fully discussed in a 

 later publication upon the effects of fertilizers. 



JONATHAN-SPOT 

 HISTORICAL REVIEW 



Jonathan-spot was first reported by Scott (17). He suggested the 

 possibility that the trouble might be due to the effects of arsenate of 

 lead. Later Scott and Roberts {18) gave a fuller report on the disease, 

 showing that it could not be due to the effects of spraying and that 

 while fungi were sometimes present in the spots they could not be taken 



