MSU Extension Apples

Apple maturity testing will occur weekly for the west central region beginning now through the end of harvest. Reports will be sent out every week, following the Michigan State University Extension fruit team apple maturity calls on Wednesday mornings. 

In the west central region, early varieties are being harvested which include Premier Honeycrisp, Zestar, and Wildfire Gala. Ginger Gold, Minneiska, September Wonder Fuji, and early strains of Gala are also showing signs of maturity development.  

Weather over the past week has been mostly warm and dry, and Thursday brought steady rain throughout the day. Daytime temperatures have been in the in the upper 70s to low 80s, and nighttime temperatures have been in the 50s and 60s. As of Aug. 24, the Enviroweather station for Hart has accumulated 2878 DD42 and 1889 DD50. Rainfall has been heavy in some locations over the past few weeks with some locations accumulating rainfall totals over 3 inches.  

Expect warm, dry conditions on Friday and Saturday this week. Another chance of rain is expected Sunday and Monday, with more accumulation. Medium range forecasts indicate slightly warmer and wetter conditions than normal. 

How to read maturity tables 

Each week, an apple maturity report will be provided and will include average values for several apple samples for varieties nearing maturity. Maximum and minimum values are included in tables below for the highest and lowest individual fruits evaluated for each, to give a full spectrum of maturity. All samples included in the reports have been untreated with ReTain or Harvista, unless otherwise noted. Samples were collected from two to four locations across Oceana County. 

For more information about apple maturity testing, review these resources compiled by Anna Wallis and Amy Irish Brown, MSU Extension. 

• Predicted apple harvest dates for 2022 from MSU  
• More information on harvest management tools and timings can be found in this article. 
• Guidelines from MSU to check for apple maturity in your own orchard, including specific pressure and starch recommendations by variety. 
• Predicting apple maturity and starch chart from Cornell University 
• Starch chart for Honeycrisp Apples developed by Washington State University. 

Maturity information for the west central region 

Ginger Gold  

Ginger Gold was sampled in two locations in Oceana County this week. Overall, samples indicate this variety is close to maturity. The main maturity index for Ginger Gold is color. Background color is largely green (4 or 5 on the background color scale, which changes from green to yellow and counts down from 5 to 1). Background color has not yet changed to pale yellow or cream (1 or 2 on the background color scale). Some fruit has developed slight pink color on sun-side of fruit. Fruit have softened from an average of 18.4 pounds of pressure (firmness) last week to 17.9 pounds of pressure this week. Sugars are increasing. Starch varied by location, and many fruit showed minimal clearing.  

Premier Honeycrisp  

Fruit were sampled from two locations on Aug. 12 and from four locations on Aug. 22 in Oceana County. Individual samples represent fruit closest to maturity or first pick fruit in each block. Some growers are harvesting first pick this week. This variety is expected to harvest about three weeks before standard Honeycrisp strains. Red color and size improved over the past few weeks following the rain and cool nights. Background color changed in early fruit to light yellow, indicating maturity, but some fruit still have green background color. Pressures are somewhat low, but Honeycrisp is typically not a very firm apple. Starch clearing varied widely across fruit with some fruit completely cleared. 

A note from Anna Wallis: Wait for acceptable varietal flavor and color to develop before picking. Picking fruit and getting it into the market early seems like an edge but will hurt repeat sales of this strain and standard Honeycrisp.

Bitter pit has been observed in some locations. Fruit that are high risk or are more susceptible to bitter pit development may be in blocks with younger trees, high-risk rootstocks, or high-vigor trees. Large fruit are also more susceptible to bitter pit development than small fruit. High bitter pit-risk fruit should be cooled quickly to the recommended 38 F storage temperature, as conditioning will exacerbate bitter pit. High risk fruit should be marketed as soon as possible. Fruit intended for longer storage should be pre-conditioned, with recommended conditions of 68 F (room temperature) for five to seven days. 

Wildfire Gala  

Fruit were harvested from two locations in Oceana County at both sampling dates. At one location, apples were treated with ReTain between sampling dates. This early strain of gala is expected to harvest approximately three weeks ahead of standard gala strains. Some growers have started first pick for Wildfire Gala. Samples this week showed maturity is at or very near harvest. Many fruit are near full red color, and background color is changing from green to a pale yellow color. Size has generally been reported as somewhat small for this variety, especially for trees with a heavy crop. Fruit firmness and starch was variable across locations. Sugars continued to increase and are at a good level.  

From Craig Kahlke, CCE LOF Program: “Exact maturity indices have not been developed yet, but near full red color, with firmness 15-20 pounds, brix 12-14, and SPI averaging 4-6 are my best guesses at this time.”

Brookfield Gala  

Early samples of Brookfield Gala were collected at one location on Aug. 12 and at three locations on Aug. 22 in Oceana County. Fruit is still mostly immature. Size is improving, especially in blocks with a moderate crop load. Red color is variable but generally improving. Background color is also improving and becoming more yellow in some locations. Fruit are generally firm, but firmness varied by location. Sugars are still low, and fruit starch is just beginning to clear.  

Pacific Gala 

A few samples of Pacific Gala were also tested this week at two locations in Oceana County. Fruit is still mostly immature, with regard to all maturity indicators. Red color and background color are still just beginning to change. On average, fruit are quite firm. Starch is just starting to clear, and sugars are low.

September Wonder Fuji 

Fruit were sampled at four locations in Oceana County this week. Fruit are generally immature, but some locations had more advanced maturity than others. Red color development is moderate, and background color is quite green. Starch is clearing at some locations, and sugars are still low.

Minneiska

Fruit were sampled at one location on Aug. 12 and at three locations on Aug. 22 in Oceana County. Minneiska (SweeTango) are an early apple with bright color. Some growers are leaf pulling or summer pruning to enhance color development for this variety. Fruit are close to maturity, and some locations had more advanced maturity than others. Red color development is increasing and will benefit from sun exposure and cool night temperatures. Background color is also changing from green to yellow. Starch is clearing at some locations, and sugars are good.

Zestar 

Fruit were sampled from one location on Aug. 12, one location on Aug. 18, and four locations on Aug. 22 in Oceana County. Fruit are showing signs of maturity, and growers are picking Zestar this week. Red color development was moderate, and background color yellowed. Starch clearing was present for fruit, and sugars are good.

Apple maturity sampling parameters 

• Ethylene (% 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. Indicates surface area covered in red and intensity of red color. 
• 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. Using Cornell Starch Iodine Index Chart.  
• Starch For Honeycrisp: will typically be rated using the standard Cornell SPI scale (1-8). However, a separate starch chart for Honeycrisp Apples developed by Washington State University (scale 1-6) also exists. 
• Brix = % sugar measured with Atago PAL-1 Pocket Refractometer 

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