Two severely affected orchards were routinely surveyed for 

 this disease in 1980 and the data in Table 1 show the percent 

 of infected fruits for the period between mid-July and mid- 

 September . 



Table 1. Percent calyx-end rot fruit infection in two severely 

 affected orchards in Massachusetts, 1980. 



Average 3.95 7.45 3.25 3.20 3.15 1.90 



The highest incidence of calyx-end rot was observed on July 

 16 with an average of 7.451. Many of the diseased fruit dropped 

 prematurely and only 1.9% of the fruits on the trees September 17 

 were infected. Visual examinations of infected fruits on the 

 trees at harvest showed a successful walling-off and healing of 

 the previously rotted calyx-end. 



Calyx-end rot and other blossom end rots of apple fruits can 

 easily be confused. The only reliable way to determine the cause 

 of calyx-end rots is to culture tissues on media in the laboratory 

 and identify the fungi that grow out. Many different fungi have 

 been associated with calyx-end rots of apple, including Botrytis 

 cinerea , Alternaria spp . , Physalospora obtusa , and Sclerotinia 

 sclerotiorum . 



Isolations were made in mid-July from 200 fruit with early 

 symptom expression and in early August from the same number of 

 fruit with late symptom expression (Table 2) . 



Table 2. Occurrence of various fungi from calyx-end rot isolations , 



Early symptom isolations Late symptom isolations 



I Incidence % Pure culture 1 incidence % Pure culture 



Sclerotinia 



60 36 18 



57 21 



20 1 



13 6 



