Assessing Optimum Harvest Dates following the 2012 Early and Extended Bloom Season

Posted: July 30, 2012

Fruit growers recognize that attention to detail can mean the difference between a crop of high quality apples picked at the proper time and a crop that has reduced market potential. Predicting optimum harvest date in this season following an early and extended bloom will require extra attention to detail, particularly with early cultivars such as Honeycrisp and Gala.
Cornell University Starch-Iodine chart in Extension Information Bulletin 221

Cornell University Starch-Iodine chart in Extension Information Bulletin 221

Dr. Tara Baugher, Penn State Extension Tree Fruit Educator


If you grow peaches, you may have noticed that days between harvests of varieties varied from what you see in a normal year following a more condensed bloom period.  It also is important to remember that sensory evaluation trials performed at Penn State demonstrated that consumers can tell the difference in taste between Honeycrisp apples harvested too early and those harvested at the proper timing.  The same consumers indicated that color was not an important factor when selecting Honeycrisp for purchase (article in 2009 Fruit Times). 

The best test for predicting optimum harvest window is the starch-iodine index (SI).  Although fruit internal ethylene measurements are somewhat more accurate, a gas chromatograph is expensive and changes in starch-iodine tend to occur earlier than changes in ethylene.  Begin testing apples two weeks before anticipated harvest, selecting apples of uniform size that appear to be most mature.  Assess the disappearance of starch in fruit tissue using a 1 to 8 scale and following the procedure published in Cornell Information Bulletin 221.  In this publication you will also find tables and graphs that will help you better understand the process of maturity development as it relates to harvest prediction.  Begin keeping yearly block by block records, and you will find this information even more useful. 

Additional maturity tests are needed once SI values indicate fruit are close to harvest maturity.  It is important with Honeycrisp, Gala and Fuji to gauge harvest window based on background color.  Fruit should be harvested for long-term storage when the background color of the fruit is changing from green to yellow.  Fruit harvested for short-term storage or immediate sale should have a cream-colored background.  Flesh firmness and soluble solids are reliable harvest indicators for most other varieties.

Wes Autio and Jon Clements, University of Massachusetts, produced a short video that shows a "painless and efficient" way to conduct SI tests in the field.  The procedure takes less time than you may think, and you'll see the difference in the marketability of your crop! 

Blanpied and Silsby.  1992.  Predicting Harvest Date Windows for Apples.  University of Massachusetts Extension.

Cowgill, Clements, Compton.  2007.  Painless and Efficient Maturity Testing.  Cornell Cooperative Extension.

Baugher and Schupp.  2010.  Relationship Between Honeycrisp Crop Load and Sensory Panel Evaluations of the Fruit.  J. Amer. Pomological Soc.


Contact Information

Tara Baugher
  • Extension Educator, Tree Fruit
Phone: 717-334-6271 x314