-17- 



becomes more susceptible to infection. Wounds made by insects, 

 wind or hail increase infections, but even without wounds the 

 fungus often invades the ripe fruit. As the fungus grows in 

 the fruit, it produces more conidia, which can spread the rot to 

 more fruit. Infected fruit can also dry on the tree to form a 

 shriveled mummy, which, after falling, can last in the ground for 

 two or more years. These mummies will produce apothecia and asco- 

 spores in the spring. The life cycle of the brown rot fungus is 

 outlined in Figure 1. 



Management 



To satisfactorily manage brown rot, it is important to pay 

 attention to the life cycle of the pathogen. In particular, the 

 following facts should be kept in mind. 



1. Spores which cause primary infections come from twig cankers, 

 stem cankers, and mummified fruit. Getting rid of cankers 

 and rotten or mummified fruit prior to growth in the spring 

 will reduce the number of spores in an orchard, and thus 

 reduce the chance of early infections. 



2. Reducing early infections reduces the number of later infec- 

 tions. Fewer spores are available to cause infection through- 

 out the rest of the season. 



3. When spores are available, they cause infection during wet 

 weather. At 45 F the infection is established in 6 to 7 hours; 

 at 70°F infection occur in 3 hours. To get protection fungi- 

 cides must be applied before a rain or before the time for 

 establishing an infection has gone by. 



4. There are two times when brown rot control is particularly 

 important; (a) during blossoming to protect from blossom 

 blight, spur blight and later twig blight; (b) during ripening 

 and harvest to protect against fruit rot. 



(a) Brown rot blossom blight: As mentioned, preventing infec- 

 tion at this time greatly aids in preventing fruit rots 

 later in the season. The number of fungicide applications 

 needed depends on rain and the fungicide used. All fungi- 

 cides should be applied around pink blossom, providing the 

 rain necessary for infection is occurring or expected. 

 Thereafter, applications may be necessary at as little as 

 3 day intervals if rain is heavy and tree growth is rapid. 

 These intervals may be extended as the rain allows. One 

 exception is the fungicide triforine 18.2% EC (Funginex) . 

 Start at pink, make a second application after 50% bloom 

 and a final after petal fall. In dilute sprays, use 12 to 

 16 fluid ounces per 100 gallons of water. For low volume 



