15 

 Summary and Conclusions. 



Bitter-pit is aij abnormal spotting of the fruit of the apple. It results 

 from the bursting and consequent breaking-down of certain cells of the 

 flesh due to too great internal pressure. This great pressure is set up by 

 the external conditions to which the trees are exposed. These trees are 

 not of themselves plastic enough to adapt themselves to their environ- 

 ment, and thereby regulate their physiological functions, with the result 

 that abnormal forces are brought into play with which the plant is unable 

 to cope in the ordinary course of events. In consequence thereof abnormal 

 physiology leads to disease conditions. The main factors that are respon- 

 sible for the spotting are believed to be excessive transpiration during 

 the day, followed by its sudden checking and complete abeyance during 

 the night, when root action is still vigorous owing to the warmness of the 

 soil. Under these circumstances water accumulation takes place to such 

 an extent in the cells of the fruit that an actual bursting of the cells may 

 occur. 



Although the results obtained thus far are in the main negative, from 

 my study of this disease I am unable to offer any ready remedy for the 

 evil, yet I can suggest lines upon which the apple grower in this country 

 should proceed if he is to succeed with the cultivation of this fruit. One 

 of the most significant facts in connection with this investigation is that 

 only those varieties of apples which escape bitter-pit and which show immunity 

 towards it are those which may be described as Colonial apples. The best 

 known amongst these are the Koo, Wemmers Hoek, and Bokveld, and 

 they undoubtedly originated from seed sown in this country. This being 

 so, it is worthy of our best attention, and it is in this direction, I am con- 

 vinced, that the future estabUshment of our apple industry lies ; that 

 is to say, we must raise our own varieties in this country and not 

 endeavour to grow foreign apples here, under the impression that because 

 certain foreign conditions appear similar to ours, fruits from those regions 

 will be suited to our climate. CHmate is the most important factor with 

 which we have to reckon in the cultivation of our plants ; in fact climate 

 practically determines the character of all plants in any geographical 

 region. Consequently, when we introduce a plant into any given 

 geographical region, it either flourishes or dies. If the former case occurs, 

 we know that the climate is congenial; if the latter, then we understand 

 that the plant has not been plastic enough to adapt itself to its surround- 

 ings. Now it may well be asked, but how is this adaptation to environ- 

 ment best brought about. It can only be done by following out nature's 

 methods, namely, by producing offspring which will be best fitted to their 

 surrounding conditions. 



We have then to make a clean start in this country so far as our apples 

 are concerned, and we have to raise South African seedlings in the localities 

 in which we wish to plant our orchards. By this means alone it is firmly 

 believed that the present difficulties will be overcome. In support of this 

 statement I have only to refer to the experience and present status 

 obtained in American horticulture, not only with the apple itself but with 

 many other familiar fruits, and from which it is abundantly clear that 



