MSU Extension

General comments

The most common question I’ve had over the last week has been, “Are apples slow to develop maturity, or is it just me?” All apple growing areas of Michigan are reporting similar situations. Growers around the Ridge are harvesting Gala and a few McIntosh. Honeycrisp are also being harvested where color is right. The biggest issue delaying harvest seems to be color; it is highly unusual to see the background color stay so green for so long. Cooler nights help with color development, but we still need some heat in the daytime to get ethylene moving. Warmer weather is in the forecast, so hopefully that will get color development and maturity moving.

Randy Beaudry, Michigan State University Department of Horticulture, wrote a summary of his thoughts on why 2014 apple maturity is moving so slowly in “Apple maturity in 2014 is slower than expected.”

Below is a table of the Grand Rapids, Michigan area predicted harvest dates for remaining apple varieties – we are surprised by how late the maturity is compared to these dates for 2014.

Predicted harvest dates for Grand Rapids, Michigan area

Pest comments

The apple maggot the trap line at the Trevor Nichols Research Center is reporting continued high apple maggot trap counts. Scouts around the Grand Rapids, Michigan area tell me that apple maggots have been low or zero for the last few weeks. If you have a sandier soil profile, you should continue watching traps for apple maggots just to be sure.

I’ve heard a few comments from growers about mice already being seen in orchards. This is the time to make an assessment of their presence to determine if you need to manage for them during post-harvest. Watch for feeding evidence in apples on the ground or for their tunneling in the orchard row middles.

Summary of Grand Rapids, Michigan apple maturity samples measured Sept. 23, 2014

Gala

Gala sampled this week compared to last have moved forward in maturity, but very slowly. Starch clearing has remained the same average of 3 this week with a similar range as last week. All fruit measured this week had ethylene over the 0.2 ppm climacteric level. Pressure readings are very similar to last week at an average of 16.8 pounds pressure this week, but the high end of the range is down a bit compared last week. Brix levels have improved only slightly at 11.3 this week compared to 11.1 last week.

Growers are reporting slow progress of Gala maturity and some blocks pick very hard off the tree. Gala are moving to the end of the long-term controlled atmosphere (CA) storage window right now and will move to the mid-term CA storage category by the weekend on the Ridge and early next week in areas north and along the lakeshore.

McIntosh

McIntosh continues to move very slowly in maturity from week to week. They are just in the window for long-term CA storage in the general Grand Rapids, Michigan area. Ethylene continues to read low with no fruits being over 0.2 ppm – very odd for McIntosh. Pressure readings are indicating good firmness at an average of 14.8 pounds, which is a decrease from the last three weeks of readings of around 16.5 pounds of pressure.

Color is excellent, particularly on the redder strains, but the background color is still surprisingly very green yet starting to change. Brix readings jumped to 12.6 this week from 11.1 last week. Starch clearing ranges from 3 to 5 with an average of 4. Like Gala, growers are reporting that McIntosh are hard to pull off the tree in some blocks without spur-picking.

Honeycrisp

Honeycrisp made a pretty big leap forward in maturity over last week’s readings. Ethylene jumped to some pretty high levels as is usual for Honeycrisp and the range of ethylene is very large with 90 percent of fruit measured being over the 0.2 ppm climacteric. A much greater number of fruits are now ready for fresh sales in the general Grand Rapids, Michigan region. Our predicted Grand Rapids area harvest date was Sept. 22.

Firmness readings are good at 13.4 pounds pressure on average. Starch readings moved from 6.4 last week to 7.7 this week and brix are up from 9.9 to 10.3 this week, which is still quite low for Honeycrisp. All the maturity indices show Honeycrisp to be right at the stage for the start of harvest. Be sure to condition Honeycrisp fruits correctly for any long-term refrigerated storage.

Varieties samples for the first time this year include Cortland, Red Cortland, Empire, Jonathan, Jonagold and Golden Delicious.

Cortland and Red Cortland

Both strains are immature at this time, according to maturity readings. Very few fruits have ethylene over 0.2 ppm. Firmness is very hard and starch clearing ratings are mostly in the 2 range with a few outliers. Brix are good at around 11 to 12. Cortland are usually ready around the same time as Empire, so if you were storing them for long-term, you could start in the next week or so.

Empire

Empire have very low ethylene levels with only 10 percent of fruits measured over 0.2 ppm. Pressure is good at an average of 15.9, but lower than usual for Empire at about a week before harvest. The range of pressure is from 13.2 to 19.8, which is more variable than usual this early in the game for Empire. Starch averages 4.2 and brix are 11.2. If the color and size are good for Empire, then they are just entering the optimum readings for long-term storage. Warmer weather later this week will likely cause ethylene to jump in Empire.

Jonathan

Ethylene is non-existent in our Jonathan samples this week. The predicted harvest date for Jonathan is Oct. 2, which will likely be a good target date for long-term CA storage. There is some harvest of Jonathan for taffy apples occurring now. There are some reports of red color bleeding in the very red strains of Jonathan.

Jonagold

Readings are very similar to the Jonathan samples with no ethylene production at this time. Firmness is lower than expected at 15.3 pounds on average. Starch clearing averages 3 and brix were 11.6. The predicted harvest date for Jonagold is Oct. 2, so they need some time.

Golden Delicious

Very low ethylene production with no fruits over 0.2 ppm. Firmness is good at 14.7 pounds, but lower than usual two weeks before harvest. Starch clearing ratings were 3.9 on average, which is higher than usual for this early in the game. The predicted harvest date for Golden Delicious for long-term CA storage is Oct. 6. Some are already in the bin for processing.

For the Hart/Shelby, Michigan area, growers can expect harvest dates for that area to be behind the Grand Rapids, Michigan area using this guide: along the lakeshore approximately six days behind Grand Rapids; areas inland about four days behind.

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.