MSU Extension

General comments

With the definite change in the weather, apple growers should see an increase in color development in varieties yet to be harvested. The high amount of rain lately is increasing splitting of prone varieties (Gala) and leading to higher bruising. Harvest is mostly complete for Gala and Honeycrisp, which means the fall harvest period has reached a peak in the Grand Rapids, Michigan, area. Next varieties to go after will be Golden Delicious, Jonagold and Jonathan.

Labor sourcing has been reported as good for the majority of growers. Some smaller acreages might be running into a bit of difficulty finding enough workers.

Brown marmorated stink bugs have been found in higher numbers in known hot spots in the last few weeks. There seems to be a marked increase in fruit damage being reported as well. Golden Delicious seemed to be especially hard hit in high pressure areas and some suspect damage is being reported in Empire as well. If you see damage that looks like bitter pit at first glance, please look closer – it is very difficult to tell the difference between bitter pit and stink bug injury. Typically bitter pit is on the clayx end of the apple and stink bug injury can be anywhere on the fruit. Photos 1-2 were taken this fall from orchards on the south end of the Ridge, closer to urban areas.

Photo 2. Empire with suspected brown marmorated stink bug injury. Photo: Phil Schwallier, MSU Extension.

Water core

The rains continue to be above normal, and water core should be on your radar for varieties susceptible to it (Red Delicious and Fuji, in particular). High water core presence reduces storage-ability. Surprisingly, water core on early varieties has not been unusually high, but that could change.

Fruit diseases – rots and summer diseases

We continue to see higher incidence of fruit rot in some blocks. Summer diseases are also very much increased with the near ideal environmental conditions for this complex of fungi. All fruit remaining on trees is very susceptible to summer diseases from now until harvest. If you have late varieties that have 10 to 14 days before you harvest them (Fuji, in particular), a fungicide application for summer disease and fruit rots should be considered in light of recent heavy rainfall totals. Fruit is essentially uncovered if you have not sprayed in the last week or so. Captan alone is not enough to prevent summer diseases and an SDHI fungicide is highly recommended.

Photo 3. Sooty blotch and flyspeck. Photo: Amy Irish-Brown, MSU Extension.

Apple maturity sampling parameters

• % fruits with internal ethylene over 0.2 ppm = indicates when ethylene begins to influence fruit ripening and it cannot be held back easily after this is reached.
• Color % = the visual percentage of red color from 0 to 100; range is of all fruits tested.
• Background color: 5 = Green, 1 = Yellow; range is of all fruits tested.
• Firmness in pounds pressure = measured with a Güss Fruit Texture Analyzer; range is of all fruits tested.
• Starch: 1 = all starch, 8 = No starch; range is of all fruits tested.
• Brix = % sugar measured with Atago PAL-1 Pocket Refractometer

Variety sampling results

The majority of Gala on the Ridge have been harvested. There are a few left and they are quickly moving into the short-term storage window, even if treated with ReTain or Harvsita. Some Gala fruits are splitting nearly in half due to rainfall and perhaps increased stem bowl russeting this season. With such a wide range of maturity on Gala this year, it is not uncommon to see very over-mature fruits in the same bins as very immature fruits.

Honeycrisp harvest is all but complete in the Grand Rapids area. Any fruit left hanging is fit for immediate sales or short-term storage.

Empire harvest began late last week on the Ridge and this variety continues to move very slowly through the maturity process as is typical. Our samples this week indicate Empire is still in the long-term CA storage range and will move to a mid-term range by the end of the week. 

Jonagold is now ready for mid to long-term CA storage for fruits not treated with AVG or 1-MCP. Treated fruits are slightly delayed, but harvest could begin any time. Jonathan are similar to Jonagold and our sample block has been harvested.

Cortland is still immature, but has made a leap forward in its maturity from last week. Cortland harvest is usually between Jonagold and Red Delicious, and they need some time yet to mature.

Golden Delicious fruits have made a definite movement forward in maturity and some harvest has begun. Our predicted harvest date is Oct. 5 and that might be on the too late side compared to the maturity data we see this week. Keep a close eye on Golden Delicious and harvest accordingly. Our maturity data indicates they are ready for long-term CA and could quickly move to a mid-term window over the next five to seven days.

Nova Spy is now moving into the mature range, but they do eat very starchy still. Nova Spy harvest is typically slightly ahead of Northern Spy.

Red Delicious was sampled for the first time this week. We should have sampled it last week. Size is excellent on Red Delicious and even blocks with a lighter crop seem to have low incidence of bitter pit. Color will improve with the cooler weather now settling in. Our predicted date for peak Red Delicious harvest is Oct. 5, which seems to be on target according to this week’s data.

Ida Red was sampled for the first time this week and like Reds, we should have sampled them last week as they seem to be a bit farther ahead than expected. Our predicted date for peak Ida Red harvest is October 10, which could be a little on the late side. We will have better idea of what Ida Red is doing with next week’s samples.

Next week we will add all the late-season varieties, including Fuji, Rome, etc.

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