RIPENING OF THE FRUIT. 79 



two the style also falls. The calyx remains permanently attached to 

 the ovary and berry. About a Aveek after the opening of the corolla, 

 the ovar3^ which at first was much narrower than the expanded calyx, 

 begins to swell and grow. This growth continues for about a month, 

 and then for about another month the green berry makes little in- 

 crease in size. A few days before the time of ripening the calyx 

 turns purplish, next the green color of the berry takes on a trans- 

 lucent appearance, the next day it turns to a light purple, and the 

 following day to a dark purple or whatever its permanent color may 

 be. During these few days the berr3^ makes a very rapid growth, its 

 diameter often increasing 50 per cent. After reaching its permanent 

 color the berry changes little in size, but for several days continues 

 to improve in sweetness and flavor. 



It is a characteristic of blueberries, important from the standpoint 

 of picking, that after ripening they will remain on the bush a long 

 time, often a month or more, without losing their plumpness or their 

 flavor. This makes possible the removal of all the berries from a 

 bush at one clean picking, unless to catch a fancy market a partial 

 early picking is desired. 



It is of interest to record that although the largest berry observed 

 on the parent bush of the seedlings of September, 1907, was 0.46 of 

 an inch in diameter, a berry ripened in the greenhouse on one of these 

 seedlings measured on April 24, 1909 (PI. XV). 0.49 of an inch in 

 diameter, and August 2, 1909. one of the same seedlings had a ripe 

 berry 0.5 of an inch in diameter. 



(36) So FAR AS OBSERVED THE SWAMP BLUEBERRY WHEN GROWN IN ACID SOILS IS 

 LITTLE SUBJECT TO FUNGOUS DISEASES OR INSECT PESTS. 



Like all plants grown in greenhouses, blueberry seedlings need to 

 be watched in order to detect and stop promptly any fungous or 

 insect pests that may appear. 



With the exception of the Asterocystis-like root fungus described 

 on page 65 as occurring on sickly plants in alkaline soils, the only 

 parasitic fungus found on an^^ of the plants was a mildew identified 

 by Mrs. Flora "W. Patterson as Microsphaera alni vae&inii, which ap- 

 peared sparingl}' when the atmosphere of the greenhouse was too 

 moist. This mildew is abundant on Vaccinium rariUans, both wild 

 and cultivated, but the swamp blueberry is very little subject to its 

 attacks, an important characteristic. This fungus would doubtless 

 respond readily to the ordinary treatment for mildew with pulverized 

 sulphur. 



Among insects a green aphis sometimes threatened to damage the 

 growing twigs, but it was easily destroyed by tobacco fumigation. 



The greenhouse red spider ( Trfivnif/rhns hrmaryldtns) infested 

 some of the cultures, especially in the warmer greenhouses, occurring 

 chiefly on the backs of the leaves, and serioush' injured the plants 



193 



