NOTICE 



The Massachusetts Cooperative Extension Service is 

 faced with a crisis situation relative to funds. There- 

 fore, in 1981 there will be only 4 issues of FRUIT NOTES 

 a winter, spring, summer and fall issue. 



CALYX-END 



ROT 

 1 



OF APPLES IN MASSACHUSETTS 



T.R. Bardinelli , C.W, 

 Department of 



McCarthy , and W.J. Manning" 

 Plant Pathology 



During the 1980 apple growing season, calyx-end rot disease 

 caused greater than usual losses. Calyx-end rot is caused by 

 the fungus Sclerotinia sclerotiorum . This organism has a wide 

 host range, including many vegetable and ornamental plants. 



The first symptoms were observed as a dry tan-colored rot 

 on the calyx end of young fruits during mid- July. Often the 

 surrounding tissue ripened prematurely causing the epidermis 

 in this area to turn red. The red areas make the diseased fruits 

 highly visible. Severely affected fruits may drop prematurely. 

 Other fungi can quickly invade the weakened fruit and furth( 

 decay results if adequate moisture is available. 



ler 



The 

 is not w 

 and may 

 periods 

 fected f 

 (1/4 - 1 

 the rest 

 can rema 

 small br 

 proper e 

 structur 

 again oc 



life cycle 

 ell unders 

 extend int 

 are probab 

 ruits drop 

 /2" diamet 

 ing or ove 

 in dormant 

 own apothe 

 nvironment 

 es are pro 

 cur. 



of S. sclerotiorum on app 



tood. Infections probably 

 o June from windblown asco 

 ly necessary for infection 



and decompose, small hard 

 er) called sclerotia are p 

 rwintering stage. On othe 



for up to 3 years, Scle 

 cia during late spring or 

 al conditions occur. Asco 

 duced and windblown to the 



les in Massachusetts 

 begin during bloom 

 spores. Wetting 

 After the in- 

 black structures 

 reduced. This is 

 r crops , sclerotia 

 rotia give rise to 

 early summer if 

 spores from these 

 host where infections 



The average incidence of calyx-end rot in Massachusetts 

 during 1980 was 2%. Severely affected orchards had losses of 

 4-8% in Red Delicious and Mcintosh blocks. The most susceptible 

 varieties appeared to be Milton, Macoun, and Mcintosh. Red 

 Delicious and Cortland fruit were also susceptible to calyx-end 

 rot but to a lesser extent and Golden Delicious appeared to be 

 the least susceptible. 



Extension Technician 



Extension Aide 



Associate Professor 



