64 



BITTER PIT INVESTIGATION, 



possibly can that will be of value to the fruit-growers of Cape Colony, as to what the spot or 

 fungus is, what it is caused through, and what is the most effectual and cheapest remedy that 

 can be employed in the Cape Colony to get rid of it." 



These apples were affected with the disease known as Bitter Pit, although Massee dealt 

 with it under the general heading of " Apple Disease," and the information required is just what 

 is wanted in connexion with the present investigation. He decided that neither fungi nor insects 

 play any part in the disease, but that it is of a purely physiological nature, being due to 

 irregularities in the ripening of the fruit. He explained that the dead rusty patches of flesh were 

 due to certain groups of cells being killed by fermentation commencing before the starch was 

 converted into sugar, and this was owing to excess of temperature during the early period of 

 ripening. He observed that the dead rusty patches occurred just beneath the skin, the reason 

 being that starch is most abundant near the periphery of the apple, and almost absent towards 

 the centre. 



He sums up with a recommendation for the prevention of the injury as follows : — " The 

 injury was due to the fruit being subjected to too high a temperature during the first period of 

 ripening. The fact that the lower half of each apple that was buried in the packing material 

 remained perfectly free from disease suggests that if the fruit was completely covered with packing 

 material, so as to exclude the free access of air, no injury would be sustained." 



Pole Evans (31) investigated the subject in South Africa, and published an account of 

 his researches in 1909. He reviewed the more important literature on the subject, and added a 

 valuable contribution of his own. After an exhaustive examination of the internal brown spots 

 he failed to demonstrate the presence of either bacteria or fungi, and also excluded any external 

 agency. He, therefore, as the result of his studies arrived at conclusions which were undoubtedly 

 an advance on any of the views hitherto propounded, and can best be given in his own words. 

 He only claimed that the present conclusions were merely put forward with a view of suggesting 

 certain lines upon which apple-growers in South Africa should work, in order to minimize their 

 losses from this trouble. 



He sums up as follows : — " Bitter Pit is an 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 

 environment, 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 diseased conditions. The main 

 factors that are responsible for 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 great 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 his fruit." 



These lines were suggested by the fact that during his investigations he found that those 

 varieties which escaped Bitter Pit, and which showed immunity towards it, were those only which 

 might be described as colonial apples. They had originated from seed sown in the country, and 

 so he suggested that the same process should be repeated. " 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 ivhich we wish to plant our orchards. By this means alone it in firmly believed 

 thai the present difficulties will be overcome." 



