100 



■ No DPA 



HsoOppm DPA 



DlOOOppm DPA 



SiSOOppm DPA 



§2000ppm DPA 

 First bar in pair is 

 Wilbraham 

 Second bar is HRC 



^Trfk^^Cfa ■7br>^& 



Harvest = 



Days <50F = 



Starch = 



Predict = 



Sept 19/21 



14/10 



1.9/2.0 



> 60% 



scald 



Oct 3/4 

 23/21 

 3.0/2.3 



20-60% 



scald 



Oct 10/11 



26/26 



3.6/4.5 



<20% 



scald 



Oct 17/19 



32/32 



4.9/5.9 



<20% 



scald 



Figure 3. Effects of DPA concentration and harvest date on scald development , 1995. 



how the dipped fruit fared after storage. 



Based on these limited data from 1995, it 

 appears that the eariest harvested fruit needed 

 2000 ppm DPA to control scald, but none of the 

 others did. A 500ppm treatment was adequate 

 for the second harvest, and DPA provided no 

 benefit for fruit from the last two harvests. It 

 should be noted that rating fruit from the last 

 harvest was difficult since the fruit were in poor 

 condition, and probably not all superficial 

 browning was really scald. 



All the data included here are from orchards 

 within 35 miles of the HRC [HRC and Orchards 

 2 (Wilbraham) and 3 (Storrs, CT) in the 

 figures], and they have climates similar to that 

 at the HRC, so it is not clear that these 

 equations will be appropriate for other areas. 

 The balance of calendar date, preharvest hours/ 

 days below 50''F, and starch score is important 



in generation of the equations. Some may 

 wonder that increasing the number of 

 preharvest days below 50°F would increase the 

 likelihood of scald incidence, and that 

 decreased starch score (less mature fruit) could 

 lead to reduced scald resistance. The reason for 

 this apparent contradiction is that these three 

 variables are themselves interrelated such 

 that, for example, scald may decrease with 

 later harvest, but the rate of decrease may slow 

 later in the season when the temperature is 

 cooler and fruit are riper. Because of the 

 importance of these relationships, and because 

 the relationships will be different in different 

 climates, we are expanding the area of data 

 collection this year to see how effective our 

 equations are in both cooler and warmer 

 regions, and we will report on Cortland as well 

 as Delicious. We should have some results in 

 the spring! 



s^ s^ ^^ ^^ ^^ 

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Fruit Notes, Volume 61 (Number 4), Fall, 1996 



