Southwest Michigan apple maturity report – September 4, 2014

The MSU apple maturity program reports for southwest Michigan helps the Michigan industry manage the apple crop.

This is the first weekly apple maturity report for southwest Michigan from now until mid-October. 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 heavy 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 program and reports webpage by Wednesday afternoon each week.

General comments

As always, the weather seems to be unusual each year and 2014 was no different. It began after an extremely long, cold winter with a late cool spring that eventually became somewhat normal in May and June. Little to no frost events occurred. This unusual spring was also characterized by considerable and seemingly unending record precipitation in most state locations.

MSU Extension predicted harvest dates for every MSU Enviro-weather station is now available on the MSU Enviro-weather website. In general, 2014 predicted apple harvest dates are roughly a week behind normal and a week behind last year. Bloom dates this spring were also behind normal across the state.

Frequent rains are requiring reapplication of pest and disease control chemicals. Marmorated stink bug reports are few so far this season. Empires and Jonathans are being picked for taffy apples. SweeTango harvest is finishing up. The lenticel russet problem is showing up again this year in some locations. The disorder appears to be worse on trees on low vigor soils and more dwarfing rootstocks like B9 and M.9 NAKB337.

Gala

Gala taste starchy. The predicted long-term storage harvest date for 2014 for SWMREC is Sept. 7. The long-term normal harvest date for Gala in Berrien County is Sept 8. Target starch index is 3.

Gala maturity summary

Date picked

Firmness (lbs)

Starch

Brix

9/2/2014

24.2

2.2

11.5

9/2/2014

23

1.5

11.6

9/4/2014

23

2.6

10.9

9/4/2014

24.8

2.2

12.4

9/4/2014

20.6

3.2

11.9

9/4/2014

26.1

1.4

11.6

McIntosh

The predicted long-term storage harvest date for main season McIntosh in 2014 for SWMREC is Sept. 11. Target starch index for McIntosh is 5.

McIntosh maturity summary (both samples from SWMREC)

Date picked

Firmness (lbs)

Starch

Brix

9/2/2014

17.5

3.4

12.7

9/2/2014

19

3.4

12.2

Honeycrisp

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

Honeycrisp maturity summary

Date picked

Firmness (lbs)

Starch

Brix

9/2/2014

18

2.2

12.4

9/4/2014

17.8

3.0

12.8

9/4/2014

19.6

2.2

11.3

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

Variety

Firmness (pounds)*

Starch index*

Short CA

Mid-CA

Long CA

Export CA

Mature

Over-mature

McIntosh

14

15

16

 

5

7

Gala

16

17

18

3

6

Honeycrisp

15

16

17

3.5

7

*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”).

Highlight – Gala maturity (thanks to Randy Beaudry, MSU Horticulture)

MSU guidelines for Gala apple maturity recommend a starch index of 3. Actually, Gala fruit with a starch index of at least 2 can be harvested for long-term storage without negative consequences. In fact, the fruit should store exceptionally well if placed in controlled atmosphere storage (CA) or treated with 1-MCP at this stage of development. Gala are a robust fruit without undue sensitivity to disorders like superficial scald, so an early harvest does not compromise storage quality. We wouldn’t, for instance, make the same early harvest recommendation for Cortland, which is extremely sensitive to superficial scald.

The Brix (percent sugars) in Gala with starch index of 2 will generally be low, but as the starch converts to sugars in storage, they should reach an adequate sugar level for the variety. However, if the fruit will be harvested, sold and consumed quickly, Gala harvest should be delayed to allow fruit to mature to better eating quality. Galas with a low starch index straight from the tree will taste starchy.

A reason for early Gala harvest is that these fruit will store well in a year in which there is a very large crop nationally, allowing us to hold on to the fruit as long as is needed to market them. Early harvest can be helpful for labor management, extending the overall harvest window. Gala fruit left on the tree will still grow in size, so an early harvest will reduce yields slightly. However, if the fruit are large, then an early harvest is advisable since larger fruit have the potential to soften more rapidly and extensively than modest-sized fruit.

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

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