A Preliminary Study of IPI\/I Options for 

 Peaches: Brown Rot 



Daniel Cooley and Arthur Tuttle 



Department of Microbiology, University of Massachusetts 



Karen Hauschild and Joe Sincuk 



Department of Plant & Soil Sciences, University of Massachusetts 



Peaches have gained more attention from 

 Massachusetts tree-fruit growers, who in 

 recent years have been looking for crop options 

 in addition to apples. Peaches can produce 

 highly saleable fruit earlier in the season, and 

 usually command a good price, particularly for 

 direct market sales. High quality peaches 

 which have been allowed to ripen on the tree 

 longer than peaches shipped from California, 

 New Jersey, or the South can get a premium 

 price. However, the riper a peach is, the higher 

 the chances are that it will develop brown rot or 

 other postharvest decays. This may happen on 

 the tree, or worse yet, on the customer's shelf. 

 While other rots can be a problem, peach brown 

 rot, caused by the fungus Monilinia fruciico/a, 

 is the most serious fungal disease problem for 

 Massachusetts growers, and fungicides used on 

 peaches primarily are aimed at managing this 

 disease. The timing of these fungicide 

 applications is based largely on tree develop- 

 ment, but it is not clear what timing scheme is 

 most effective and efficient. 



The biology of the fungus suggests that 

 there are two critical times when peaches 

 should be protected: bloom and fruit ripening. 

 Brown rot infections on peach develop during 

 these two phenological stages. Blossom blight 

 may cause flowers to wither, turn brown, and 

 die, and later produce spores which later infect 

 fruit. These blossom infections may also move 

 into twigs and cause significant damage when 

 conditions for disease development are highly 

 favorable. Normally blossom infections remain 

 quiescent, or latent, until fruit starts to ripen. 



Then, the infections will start to grow, produce 

 spores, and spread to other ripe fruit. Between 

 bloom and harvest, fruit susceptibility to 

 brown rot remains quite low from pit hardening 

 to 2 weeks before full ripeness (Biggs and 

 Northover, 1988). By monitoring pit hardening 

 and ground color, growers might eliminate 

 fungicide sprays during this period, and get 

 better brown rot control. 



Materials & Methods 



To examine the effect of reducing fungicide 

 use for managing brown rot during pit 

 hardening, an experiment was conducted at the 

 University of Massachusetts Horticultural 

 Research Center during the 1996 growing 

 season. The experiment was conducted in two 

 blocks of peaches, one Redhaven and the other 

 Glohaven. Each treatment plot consisted of 

 three trees. There were three replications of 

 the experiment in the Redhaven block and four 

 in the Glohaven block. 



Sampling for pit hardening was done in 

 mid- through late June. Until pit hardening in 

 early June, all treatment plots received 

 standard calendar-based fungicide applica- 

 tions every 7 to 10 days, starting at early bloom. 

 These consisted Captan 80WP at 1 lb/100 gal. 

 After that time, fungicides were applied 

 according to four treatment patterns. In one 

 treatment, the calendar applications were 

 continued at 7 to 14 day intervals, using 

 Captan (SOW, 1 Ib./lOO gal.) on the early spray 

 dates or the same rate of Captan plus Benlate 



Fruit Notes, Volume 62 (Number 4), Fall, 1997 



