-16- 



BROWN ROT OF PEACHES: AN UPDATE ON MANAGING THE DISEASE 



Daniel R. Cooley , Christopher M. Becker 



2 

 William J. Manning 



Department o£ Plant Pathology 



Where peaches, plums and cherries are still grown in Massa- 

 chusetts, brown rot remains the most serious disease problem on 

 these fruits. It attacks blossoms, spurs, twigs, stems and fruit. 

 Throughout the season, and after harvest, brown rot is a problem. 



The Life Cycle of The Fungus 



Brown rot is caused by a fungus, Monilinia fructicola . This 

 fungus survives the winter in cankers, on twigs and branches, or 

 in mummified fruit. In spring, when the first green tissue appears 

 on fruit trees, the fungus also starts to grow. It produces a 

 grayish fuzzy mold, which contains a huge number of spores called 

 conidia. These conidia will produce new infections when they are 

 carried to new, growing tree tissue. 



Conidia are not the only type of spore produced by the fungus. 

 Ascospores are also released in the spring. Tiny cup-like "mush- 

 rooms" grow from mummified fruit on the ground, and ascospores are 

 released as visible clouds from these structures when conditions 

 are right. 



Air currents carry ascospores and conidia to new tissue. Flowers 

 are particularly susceptible. It takes only a few hours for these 

 spores to germinate and cause infection. If unchecked, the fungus 

 grows in two ways. It quickly produces new tufts of conidia on 

 blossoms which are then released. It also grows down the blossom 

 petiole to the fruit spur and twig. In the twig, a reddish-brown, 

 sunken canker develops. The twig is often girdled by the fungus 

 and soon dies. The surface of lesions soon grows greyish tufts of 

 conidia. These conidia will infect fruit later in the season. 



Brown rot does not infect leaves and/or bark directly, but grows 

 in from blossom and fruit infections. Ascospores and conidia do 

 not live long. The apothecia which produce ascospores also disinte- 

 grate in late spring. Therefore, when fruit ripens, the ascospores 

 have disappeared. When ripening fruit become infected, the infec- 

 tion is caused by conidia from twig cankers. As fruit matures, it 



1 



Extension Technician 

 2 



Extension Plant Pathologist 



