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

Reports of brown marmorated stink bug juveniles and adult catches have increased sharply over the past week according MSU entomology technician Mike Haas. “Brown marmorated stink bug numbers were up this week in the southwest. The catching traps were in three different sites: two Stevensville sites and one near Niles. A total of 36 insects were captured, 22 in three rescue traps and 14 in three pyramids. Eleven were adults and 25 were nymphs. These traps are included in the MSU trapping network and are baited with both the Harlequin bug and the Halyomorpha halys lures.”

Ongoing rains have made it difficult to keep up with summer disease spray programs. Insects of concern include larvae for the end of the second generation codling moth and for the third generation of oriental fruit moth. Recent weekly trap catches of oriental fruit moth have exceeded 90 moths per trap in a few area orchards.

Specific apple variety comments

Harvest of Gala has begun in the area. Growers are focusing on red strain types with good color and decent size. Firmness average dropped approximately 3 pounds with the current average at 20.2 pounds. Starch conversion average moved from 2.2 last week to 4.1 for this week. Galas intended for long-term controlled atmosphere (CA) storage should be harvested before firmness drops to 18 pounds.

Gala maturity summary

The predicted long-term storage harvest date for 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 starch index is 3.

McIntosh harvested from SWMREC are still testing above the 16-pound firmness and 5 starch index recommended for long-term CA storage.

McIntosh maturity summary (both samples from SWMREC)

The predicted long-term storage harvest date for main season McIntosh in 2014 based on the SWMREC Enviro-weather station is Sept. 11. Target starch index for McIntosh is 5.

Honeycrisp samples are testing close to the recommended firmness – 17 pounds – and starch index – 3.5 – recommended for long-term CA. This variety seems to be ahead of the predicted long-term storage date of Sept. 19. Spot-picking of Honeycrisp has started in some of the most advanced blocks.

Honeycrisp maturity summary

The predicted long-term storage harvest date for Honeycrisp in 2014 for SWMREC is Sept. 19. Target starch index for Honeycrisp is 3.5.

Early Fuji varieties were not sampled, but should be ready on some farms. Early Fuji is a group of varieties that ripen approximately six weeks ahead of main season Fuji varieties. Early Fuji varieties include the blush types September Wonder, Rising Sun, Auvil and Daybreak, and the stripe types Morning Mist and Nickell. Quality is not quite as good as the main season selections.

Suggested firmness and starch index levels for long-term and shorter-term storage by variety

*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.