Apple Maturity Assessments

Routine measurements of fruit starch levels, ground color and other maturity indices allow growers to make improved decisions about optimum harvest dates for long-term storage. During August through the end of October, 2017, this site will be updated weekly with both tables and photos that demonstrate progressions in apple maturity.
Blush and ground color changes as fruit mature. Photo by Brianne Redman.

Blush and ground color changes as fruit mature. Photo by Brianne Redman.

The Mid-Atlantic apple industry is going through a number of dramatic changes due to the planting of high density orchards with newer cultivars. These transitions, coupled with climate and weather changes, make it difficult for growers to predict optimum fruit maturity for long-term storage.

To track developments in physiological maturity, we will measure starch pattern, firmness, soluble solids, fruit size, % red color and ground color changes (visually and with a Delta A meter). The cumulative data will be presented here, and summaries of Starch Pattern Index and Delta A values will be posted each week at Fruit Times. The starch index measures the loss of starch in the flesh, while Delta A values are being evaluated as a measure of changes in ground color.

Our working hypothesis is that ethylene—sometimes referred to as the fruit ripening hormone—increases as fruit mature, leading to the coordinated ripening of apples. Ethylene initiates new enzyme production in fruit that affects visible attributes like surface color and ground color, as well as hidden attributes like starch pattern index, flesh firmness and soluble solids.

The project is supported by the State Horticultural Association of Pennsylvania Research Committee and is a cooperative effort of University of Maryland Extension and Penn State Extension.

Subscribers to the electronic version of Fruit Times will receive the weekly reports by emails easily read on a smart phone. If you receive the paper copy of Fruit Times, visit your library for the weekly updates that will be posted at Penn State Extension Tree Fruit Production. To sign up for electronic updates, visit Subscribe to Our Email List.

For more information contact:

2017 Apple Maturity Assessment Articles 

In response to an early bloom, wet spring and dry summer, apples matured earlier than normal in 2017.

We again sampled Aztec Fuji, Cripps Pink (Pink Lady) and Granny Smith this week.

This week we sampled Aztec Fuji, Cripps Pink (Pink Lady) and Granny Smith grown in Maryland.

Apple harvest in 2017 has been well ahead of “normal.” This week we again sampled late-season apples, Cripps Pink (Pink Lady) and Granny Smith.

Granny Smith fruit harvested from Western Maryland are nearing storage maturity, and Cripps Pink fruit are beginning to lose ground color.

Apple harvest in 2017 has been well ahead of “normal.” To update you on late season apples, this week we sampled Nagafu Fuji and GoldRush.

This week we received three fruit samples from a Maryland grower who grows a wide variety of ‘newer’ apple cultivars for direct-market sales.

Daybreak Fuji and Olympic Asian Pear are ten days ahead of last year.

Focus on Honeycrisp, what a difference a week makes!

With the continued cooler temperatures and heavy rainfall in August, fruit size and red color are good. Gala harvest is in full swing; picking began soon after we sampled.

Week 3 maturity assessments indicate a need to be ready for an early apple harvest and possible spray applications to prevent preharvest drop.

This week, maturity of Premier Honeycrisp, Honeycrisp and two red Gala cultivars are compared.

August 1, 2017 we collected our first fruit samples for assessments of the maturity of Premier Honeycrisp, Honeycrisp, Buckeye Gala, and Ultima Gala.