MSU Extension

General comments for this week

Good weather for harvesting is continuing. More labor is becoming available for apple harvest as vegetable crops wind down. Fruit are attractive this year with generally good skin color for newer redder strains and classic fruit shape.

Harvesting of the last of the Golden Delicious, Red Delicious and Fuji is underway. Braeburn, Goldrush and Granny Smith have yet to be harvested. Rome, Fuji and Red Delicious fruit are relatively large this year. Watercore and red in the flesh are becoming more common for Red Delicious and Romes.

Apple feeding damage by brown marmorated stink bugs is still relatively minor in the few locations where the insect has been detected feeding on fruit. The beetles moved into the orchards in late summer when fruit were nearly full sized. As a result, external signs of feeding on fruit are inconspicuous and look like tiny pinpricks from the slender feeding tube, sometimes with a barely visible drop of ooze. Internal feeding damage are small, slightly discolored flesh areas 0.25 to 0.33 inches below the peel. The internal damage darkens and becomes more obvious in storage. The discoloration can be mistaken for corky spot caused by calcium deficiencies.

This is the final apple maturity report from southwest Michigan in 2015.

Detailed tests for this week – see suggested firmness and starch levels for harvest in Table 1

No more reports for Ida Red. Most in the area are picked. This variety is very mature.

This is the fifth report for Golden Delicious. Fruit firmness this week tested 16.3 pounds with starch clearing index of 6.3. Golden Delicious has a predicted harvest date for long-term storage of Sept. 28 for Berrien County. Golden Delicious has a target firmness of at least 17 pounds for long-term and 16 pounds for mid-term CA storage and starch index of at least 3 for flavorful short-term direct sales. All sites are testing mature for starch clearing (eating maturity). Firmness readings indicate fruit are suitable for long to short-term CA storage, depending on the site. Skin coloration in a few sites is showing the yellow orange hue of very mature fruit.

This is the fifth report for Red Delicious. Fruit firmness this week tested 16.8 pounds, slightly less than last week’s 17.1 pounds, with the starch clearing index now averaging 4.5. Red Delicious has a target firmness of at least 18 pounds for long-term CA and 17 pounds for mid-term CA. Four out of six sites have firmness testing in the mid-term or short-term CA storage category. Vascular bundles at the core line are staining red in fruit of some highly colored Red Delicious strains. Watercore is evident in the largest, most mature fruit.

This is the third report for Rome. Fruit firmness this week averaged 20.8 pounds compared to 21.2 pounds for last week, with starch clearing index of 5.0 compared to 3.8 for last week. The target firmness for long-term storage is at least 18 pounds, and recommended starch index for direct sales is 3.0 or higher. Harvesting of Rome for processing has been in progress for the past four weeks. All four sites tested had sufficient starch clearing and firmness for successful long-term CA. The mature date for this variety for central Berrien County was predicted to be Oct. 5.

This is the third report for Fuji. Fruit firmness this week tested 17.6 pounds, slightly less than last week, with a starch clearing index of 5.7, same as last week. Fuji has a target firmness of at least 18 pounds for long-term and 17 for mid-term CA storage and starch clearing index of 3.0. Predicted harvest dates for Fuji for central Berrien County is Oct. 20. This variety typically softens slowly and brix increase seems to be triggered by cooler weather. Better eating quality is obtained by holding off harvesting until the background loses both the strong green color and the very smooth skin of an immature apple.

This is the second report for Braeburn. Fruit firmness this week tested 19.8 pounds, only slightly less than last week, with a starch clearing index of 4.0 compared to 2.9 last week. Braeburn has a target firmness of at least 18 pounds for long-term CA storage and minimum starch index of 3 for more immediate direct sales. Predicted harvest dates for Braeburn for central Berrien County is Oct. 20. Current fruit firmness will allow harvest to be delayed to wait for better brix, skin color and fruit size. Little amounts of watercore can be found in fruit in some orchards.

*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 clearing 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 by Blanpied and Silsbey, Cornell Extension Bulletin 221.)

* Indicates revised dates

The samples for these reports are collected primarily in Berrien and Van Buren counties – the maturity is only a broad indication of trends for this area. Sites north of here, closer to Lake Michigan, on heavier soils or with heavier crop loads will generally harvest later.

Contact Bill Shane at the Southwest Michigan Research and Extension Center (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 Michigan State University Extension Apple Maturity page by Wednesday afternoon each week.

Looking for more? View Michigan State University Extension’s Apple Maturity page for regional reports throughout the state and additional resources.