22 



Decay can be controlled adequately with postharvest fungicide dips but 

 resistance to applying pesticide after harvest and problems with application 

 preclude their use. Other means must be used to control postharvest decay. 



Postharvest Handling 



The simplest and most effective way of maintaining blueberry quality after 

 harvest is with the use of refrigeration . Cold temperatures slow ripening and 

 nearly stop decay. Some resistance to the extensive use of refrigeration of 

 blueberries exists because many growers are concerned that the sweating of 

 fruit after removal from the cold can increase decay, but research has shown 

 that decay is not significantly increased by sweating (4). 



The optimum conditions for holding blueberries are 31 to 32*^F and 95% 

 relative humidity. Even at 40° there is substantially more loss to decay than 

 at 32" (Table 4). Under most circumstances, blueberries may be kept for 2 



Table 4. Percentages lost associated with holding temperature, 

 and Kushman (6). 



From Hruschka 



Length of storage 



weeks at 32° with very little loss (4). However, if some loss can be tolerated 

 they may be kept for up to 6 weeks. Late-harvested berries will not store as 

 well as early-harvested fruit, and any decay present at harvest will reduce 

 storage potential by providing an inoculum source (7). 



Also, it is critical to cool the berries as quickly as possible. Ceponis 

 and Cappellini (5) studied the differences in losses associated with cooling 

 rate. Berries were cooled in 2, 48, or 72 hours and kept at 35°F for 2 weeks, 

 after which they were removed from storage and kept at 70° for up to 3 days. 

 Table 5 shows their results, and it is obvious that rapid cooling reduced 

 losses, particularly in the first 2 days after being transferred to 70°. Many 

 growers may not have cooling equipment available to reduce the temperature of 

 their berries to 35° in 2 hours, but it is important to cool them as quickly as 

 possible . Some success has been obtained by supplementing existing cooling 

 equipment with liquid nitrogen or CO2 to speed the cooling process (9). 



Modified atmospheres around the fruit may improve longevity. Elevated CO2 

 (10 to 15%) seems to be the most advantageous modification because it inhibits 

 the growth of decay organisms. Table 6 shows data on fruit losses to decay 



