31 



similar, although apparently not identical condition. x\nd there 

 are cases where improper painting of trunks has caused trouble. 

 But when all these things are considered, I am not satisfied in my 

 own mind that I can satisfactorily account for half of the so-called 

 Collar Rot that I have seen. 



Though we can not yet speak certainly about its causation, we 

 ought to take precautions against its possible spread. In hunting 

 borers in orchards afifected with collar rot, free use should be made 

 of disinfecting solution on all wounds and tools. Close watch should 

 be kept for the fi.rst signs of the trouble, and the afifected area cut 

 out as thoroughly as may be, leaving the live bark with, a smooth 

 edge for healing. The cut surface should be washed with bi- 

 chloride of mercury or strong lime-sulphur as a disinfectant, and 

 the surface painted with pure lead and oil paint or tar. When the 

 exposed surface is large, and alcove ground, a coating of grafting 

 vrax will prevent drying out, and promote healing. Diseased trees 

 should be prevented from carrying a full crop of fruit, and atten- 

 tion should be paid to securing proper soil moisture and aeration 

 and fertilization. Judicious reduction of foliage by summer prun- 

 ing would doubtless be helpful. 



We come next to those constitutional disorders that we call 

 physiological diseases. They are not caused by organisms of any 

 sort; they result from derangements of the normal physiological 

 functions of the plant parts, usually due to unfavorable environ- 

 mental conditions. Our knowledge of them at present is meagre ; 

 and from their nature control measures are unfortunately of limited 

 applicability. Such troubles are Fruit Pit (perhaps more usually 

 known as Baldwin Spot, although this term is also sometimes con- 

 fusingly applied to Fruit Spot mentioned above), W^atery Core, 

 Watery Apex, Sun Scald. Sticky Skin, and probably Jonathan Spot. 



Fruit Pit shows rather large, vaguely outlined, slightly de- 

 pressed spots, that suggest finger print bruises. Under these the 

 flesh is dead for some distance, and later the surface becomes dead 

 and brown. Frequently afifected areas can be found in the interior 

 of the flesh. The cause is supposed to be lack of sufficient moisture 

 at certain periods in fruit development, especially sudden changes 

 from wet to very dry conditions. It mav be that tillage methods 

 can be so developed as to equalize the soil water supply sufficiently 

 to reduce this trouble to a minimum. 



Watery Core and Watery Apex seem to be diff^erent forms of 

 the same trouble. Continued deficiency of water may cause the 

 cell sap to reach such high concentration as to kill the living sub- 

 stance, and there is a consequent diffusion of sap into the small 

 spaces in the apple tissue, giving the watery, instead of the whitish, 

 opaque appearance ; or a sudden access of water after the cell sap 

 has become highly concentrated, may result similarlv. 



Sun Scald is injury to the cells from intense heat. It is ac- 

 companied by abnormal ripening of tissues in the vicinity. It may 

 be aggravated by liquid on the surface of the exposed fruit and is 

 frequently seen on fruit suddenly exposed to the sun's rays after 

 being shaded. 



