MSU Extension

This is a weekly Michigan State University Extension apple maturity report for southwest Michigan from early September until mid-October. The samples for these reports are collected primarily in Berrien and Van Buren counties. Sites north of here, closer to Lake Michigan, on heavier soils or with heavy fruit loads will generally harvest later.

Reports from the current and past years for southwest Michigan and other regions are posted at the MSU Apples website.

General comments

Fruit picking and apple hauling truck activity in southwest Michigan has increased as growers target the last of Jonagold and turn their attention to Golden Delicious and some Red Delicious.

Brown marmorated stink bug trap numbers are continuing to climb. Homeowners close to ravines, rivers and creeks are noticing these insects climbing on windows and sidings looking for overwintering sites.

The Trevor Nichols Research Center (TNRC) still reports catching apple maggots last week near Fennville, Michigan. Codling moth catches are near zero, but oriental fruit moths are still active and could still be a threat in late harvested apple orchards.

Specific apple variety comments

Gala testing reports have ended in southwest Michigan. Most of the larger blocks have been harvested. Waxiness and cracking is common on fruit still on the trees. Gala firmness last week was down to an average of 18.4 pounds and a starch conversion index of 6.8, well into the mature zone.

The predicted long-term storage harvest date for Gala in 2014 for the Southwest Michigan Research and Extension Center (SWMREC) is Sept. 7. The long-term normal harvest date for Gala in Berrien County is Sept. 8. Target minimum starch index for immediate direct sales is 3.

Honeycrisp testing reports have ended in southwest Michigan. Honeycrisp firmness last week averaged 15.9 pounds with starch conversion of 6.1. The recommended firmness for mid-term controlled atmosphere (CA) storage is 16 pounds, with a minimum starch conversion of 3.5 needed for good flavor. The predicted long-term storage harvest date for Honeycrisp in 2014 for SWMREC is Sept. 19.

Jonagold testing reports have ended in southwest Michigan. Last week’s samples from Berrien County averaged 17.1 pounds firmness, the recommended minimum firmness (17 pounds) for long-term CA storage. Fruit in general had sufficient internal maturity last week for harvest as indicated by this week’s average starch index of 5.0, above the 3.5 minimum recommended for long-term CA storage.

Jonathan testing reports have ended in southwest Michigan. Last week’s samples averaged 16.9 pounds firmness – the ideal minimum firmness for good, long-term CA storage is 16 pounds. Starch index at that time averaged 3.9, slightly better than the minimum target maturity of 3.5 for optimal long-term CA storage for apples intended for fresh market sales. The predicted long-term storage harvest date for Jonathan in 2014 for SWMREC is Oct. 1.

Golden Delicious orchards in central Berrien County are testing an average of 17.9 pounds firmness with an average starch index of 3.8, now with sufficient internal maturity for good flavor in short-term sales and sufficient firmness still for long-term CA storage. Minimum recommended firmness for long-term CA is 17 pounds with a starch reading of 3 or more. Current brix is at 13.7, slightly better than last week.

Golden Delicious maturity summary

The predicted long-term storage harvest date for Golden Delicious in 2014 at SWMREC is Oct. 3. Target starch index for Golden Delicious is 3.

Red Delicious picked Monday, Sept. 29, are averaging 18 pounds firmness at the minimum recommended firmness for fruit destined for long-term CA. Starch conversion index averaged 2.6, slightly above the target of 2.5 for long-term CA. Based on these tests, some blocks could be harvested successfully for long-term CA storage. The firm skin of Red Delicious allows harvest to be delayed, waiting for better size and skin color or harvest crew availability.

Red Delicious maturity summary

The predicted long-term storage harvest date for Red Delicious in 2014 for central Berrien County is Oct. 7. Target starch index for Red Delicious is 2.5.

Ida Red picked Monday are averaging 18.2 pounds firmness, considerably above the 16 pounds minimum recommended firmness for fruit destined for long-term CA. Starch conversion index averaged 2.2, below the 3.5 sought for best long-term CA. Based on these tests, harvest could be delayed.

Ida Red maturity summary

The predicted long-term storage harvest date for Ida Red in central Berrien County is Oct. 11. Target starch index for Red Delicious is 2.5

Fuji picked this week are averaging 19.6 pounds firmness, above the 18 pound minimum recommended firmness for fruit destined for long-term CA. Starch conversion index averaged 3.3, slightly above the target of 3.0 for successful long-term CA storage. Based on these tests, some blocks could be harvested successfully for long-term CA storage. However, the excellent firmness will allow harvest to be delayed to wait for better size, skin color, brix and eating quality. Fuji approaching the maturity for good eating quality has more noticeable lenticels, which gives the skin of the fruit a slightly bumpy texture.

Fuji (traditional season strains) maturity summary

The predicted long-term storage harvest date for Fuji in central Berrien County is Oct. 25. Target starch index for Fuji is 2.5.

Suggested firmness and starch index levels for long-term and shorter-term (CA) storage for selected varieties

*Firmness is measured with a mechanical 11-millimeter wide probe inserted into the pared flesh of a fruit to a distance of 8 millimeters. Starch index is measured on equatorial cross section of an apple stained with iodine solution and rated using the Cornell University starch-iodine index chart for apples on a 1-8 scale (“Predicting Harvest Date Window for Apples”).

Contact Bill Shane at the SWMREC, 269-944-1477 ext. 205, or 269-208-1652, if you would like to have samples from your farm tested for maturity. Statewide reports will generally be available on the MSU Apple Maturity Program and Reports page by Wednesday afternoon each week.