-9- 



posltlon In the cluster was noted. The ultimate size seems to be largely deter- 

 mined during the initial growth period," 



Bags of aluminum foil and white and black cloths were used to control 

 light conditions for berries on the bush and special chambers were used to study 

 temperature Influence on the harvested berries. They found that "alumintjm 

 and both black and white cloth bags delayed maturity but resulted in larger 

 fruits » Harvested berries ripen faster at high temperature and in the light. 

 However, color formation will proceed in the absence of light." 



-~W. J. Lord 



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FACTORS TO CONSIDER IN THE CONTROL OF 

 BROWN ROT OF PEACH AND OTHER STONE FRUITS 



The brown rot fungus organism attacks blossoms, twigs, and fruit to cause 

 blossom blight, twig blight, stem cankers, and fruit rot. The fruit and trees 

 can be protected by spraying at the right time. 



The source of spores for spring infection are mummies on the tree from fruit 

 rotted and previous year, mummies on the ground, and twig and stem cankers from 

 infections of the previous year. The spores on these organs may be overwintered 

 spores or newly produced spores. They Infect blossoms and twigs which in turn 

 produce additional spores to infect fruit and twigs later in the season. 



There are two critical periods when most of the infections take place and 

 which need careful grower attention if conditions are favorable for Infection. 

 They are (1) during bloom and (2) as the fruit approaches ripening. 



Blossoms are especially vulnerable during the 7 to 14 days of the bloom period. 

 The fungus attacks the flower parts, especially when they start to wither, and causes 

 blossom blight. It then grows down into the twig to cause twig blight and stem 

 cankers . 



Infection can occur dally if there is rain or moisture from fog or heavy dews. 

 Infection will take place in 6 to 7 hours when the temperature is 45°F, in 4 hours 

 at 60°F, and in 3 hours at 70°F. A tight protective schedule with sulfur or dichlone 

 Is necessary for control of blosscm blight If there are rains during bloom. When 

 rains are heavy and wash off spray deposits, it pays to spray or dust again without 

 delay. 



The other critical time for control of brown rot is when fruit approaches 

 maturity and the closer to maturity the more easily it become infected and the 

 faster the fruit rots. Here again, Infection depends on moisture and also there 

 is more of it if insects are not controlled and there are feeding injuries. 

 Beginning one month before harvest, it will pay the grower to watch the weather and 

 spray to protect during rains and to renew spray if heavy rains wash off spray de- 

 posits. The last spray of the season can be with captan which will delay rot longer 

 than other fungicides after peaches are harvested. 



— C. J. Gllgut 

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