Category Archives: Harvest maturity

Predicted Harvest Dates for Winchester and Central Virginia

Predicting harvest date depends upon many factors, including full bloom date, accumulated heat units (growing degree days) over the course of the growing season, physiological stressors (e.g., disease and insect damage or drought), day to night temperature differentials as harvest approaches, and the amount of precipitation. However, the number of days between full bloom and harvest has been shown to be the most reliable predictor of harvest date.

More than two decades ago, researchers in Michigan determined that there there are an average of 143 days between full bloom and the first commercial pick of Red Delicious apples that are to be held in controlled atmosphere storage (i.e., firmness between 17-18 lbs; starch between 2.5-4 on the 8-pt scale Cornell Starch Chart). Additional seasonal adjustments above or below the average number of days until harvest are made based upon the average daily minimum temperatures for the 15 days after full bloom.

For the past several seasons I have tested the Michigan model using fruit from a block of Bisbee Red Delicious on MARK rootstock. Results to date have shown that this model is very good at predicting harvest maturity in Virginia.

Based on the Michigan model, here are the predictions for 2013:

In Winchester, Bisbee Red Delicious full bloom was April 23 and average minimum temperature for the 15 days after full bloom was 8.0°F less than 50°F. Using this data in the Michigan model, harvest is predicted ~8 days more than 143 days between full bloom and harvest. This puts the predicted harvest date for the first CA pick of Red Delicious at September 19.

In Central Virginia (Piney River), full bloom for Red Delicious was estimated to be April 20 and the predicted harvest is September 14.

Since most growers have Red Delicious trees in their orchards, other cultivars (and strains of Red Delicious that ripen earlier than Bisbee) can be estimated based upon experience on their picking date relative to Red Delicious.

Another method for estimating harvest date uses the rule-of-thumb that says, “for each 2-3 days departure for the normal bloom date, there will be a one-day departure from the normal harvest date.” (Blanpied and Silsby, 1992).

You can find more information about harvest maturity indices in a post from last year.

In the next week or two, I will start conducting maturity evaluations of fruit from the Winchester AREC and surrounding orchards.

References

Blanpied, G. and K. Silsby. 1992. Predicting Harvest Date Window for Apples. Cornell Information Bulletin 221. <<pdf>>

Beaudry, R., P. Schwallier, and M. Lennington. 1993. Apple Maturity Prediction: An Extension Tool to Aid Fruit Storage Decisions. HortTechnology 3(2): 233-239.

Maturity Report — October 11, 2012

Today we measured the maturity of Stayman, Granny Smith, and Pink Lady grown on the AREC farm. Picking of Stayman and Granny Smith for long-term storage should be finishing up. Pink Lady’s have colored really well over the past week and can be spot picked, or in blocks that have well colored fruit, trees can be picked clean.

This will be the last maturity report for 2012. Good luck with the final stretch!

2012 Fruit Maturity Oct 11

Maturity Report — September 25, 2012

Cool weather over the region for the past week has helped space out the harvest for mid- to late-ripening apple varieties. Expect similar conditions, with a bit more rain over the upcoming week. Nonetheless, we’re still running 10 to 14 days early on the later ripening varieties.

In the Winchester area, Rome harvest is in full swing and York harvest is starting to ramp up.

Most Fuji strains are ready for harvest. This is probably the last week Fujis should be harvested for long-term storage.

Surprisingly, Granny Smith apples are ready for spot picking for long-term storage.

Stayman and Pink Lady apples are coloring very nicely, but have not yet started to develop varietal flavors.

Open this pdf to see the full dataset:

2012 Fruit Maturity Sept 25 (pdf)

Maturity Report — September 17, 2012

Harvest maturity report for Sept. 17:

2012 Fruit Maturity Sept 17 (pdf)

In general, the cool weather has greatly reduced fruit maturity over the past week. Along with today’s rain, this should give everyone a chance to catch their breadth. Other than a less than 50% chance of rain over the weekend, the next 10 days looks like excellent weather for picking. The cool nights have also further increased red color development. Overall, fruit quality seems to be very good this year.

At the AREC, Fujis, Romes, Idareds are ready for harvesting for long-term storage. Staymans and Yorks have not started to ripen on the trees yet.

Maturity Report — September 11, 2012

Here’s the latest maturity report using apples grown at the AHS Jr. AREC in Winchester or nearby:

2012 Fruit Maturity Sept 11

We’ve had adequate rainfall, which has helped overall fruit size in most orchards. Additionally, with the cooler night temperatures that we’ve been experiencing in the northern Shenandoah Valley, ripening has moderately slowed down which will allow for increased red color development.

Nonetheless, Reds, Goldens, early Fuji strains, and Empire without ReTain are ready for harvest and may be past their prime by the middle or end of next week. Many of these apples are already moving past the ideal starch readings for long-term CA storage.

Romes are probably going to be ready shortly (next week?), followed by Stayman and Idared. Additional fruit size increase will be gained for Yorks that are allowed to stay on the tree for a couple of more weeks.

Many of the blocks that we are collecting fruit from were sprayed with ReTain, so ethylene and starch readings in our reports are going to be lower than in non-sprayed blocks. As always, please check with your buyer before you harvest.

Maturity Report — September 5, 2012

The pdf linked below contains the maturity measurements through yesterday, September 5.  Samples were only taken from the Alson H. Smith, Jr. AREC and a few nearby farms in Winchester. With a small sample size, this information is only meant as a general guide as to the maturity of apples in the area. Maturity at your own orchard may be different. Additionally, the use of NAA, ReTain, and 1-MCP (SmartFresh) will affect maturity. For more information on maturity testing, please see my previous post.

Cultivars tested include:

  1. Red Delicious
  2. Golden Delicious
  3. Empire
  4. Fuji
  5. York
  6. Rome
  7. Idared
  8. Stayman

According to these data, Red Delicious, Golden Delicious, and Empire can still be picked for long-term storage and for about another week for shorter term storage. Some early coloring strains of Fuji are ready for harvest. Later strains will benefit from additional time spent on the tree to develop red color and varietal flavor. Rome, Idared, and Stayman are at least one to two weeks away from harvest.

Will any fruit still be on the trees in October?!

2012 Fruit Maturity Sept 5

Maturity Report — August 30, 2012

The below linked pdf contains the fruit maturity data to date. Please note that the August 28 sampling consists only of measurements from fruit grown at the Alson H. Smith, Jr. AREC. Due to differences in location, soils, rootstocks, strains, etc. these data may not represent the fruit maturity in your own orchards.

Please see my previous post about maturity indices for more information about the different maturity measurements. And, my post on the annual end of August maturity testing to see how this year compares to previous years.

Maturity Report 8_30_12

Annual End of August Apple Maturity Report

For 26 years, researchers at the Alson H. Smith, Jr. AREC have recorded Golden Delicious and Red Delicious apple maturity data from orchards based in and around Winchester. Data for Empire has been taken for ten years and for Gala for five years. In recent years, we have added other commercially important cultivars to the analyses in order to generate long term averages. These data provide an interesting insight into the current season’s harvest, and can help growers make decisions on when to pick different blocks.

Earlier this season, I discussed the potential for a very early harvest. Based on a model developed at Michigan State University, the first Red Delicious harvest was estimated to be August 27 in Winchester and August 25  in Central Virginia (see post from June 28). While extraordinarily early, this prediction may be fairly accurate. Red Delicious Brix are already at 11.9 (two brix units greater than the long-term average) and firmness is down to 18.2. I have already heard of Reds being picked in Central Virginia, but not yet in the Winchester area.

Another one of my concerns with this early season was the potential for there to be poor color development. This has not come to fruition, and in fact, on Red Delicious, Gala, and Empire red color is the highest it has ever been at this time of year. The cool nights predicted for the next 10 days, should further enhance color development.

Below are the data from this year’s end of August apple maturity sampling. In each year, the samples were taken around August 25 and consist of apples from the AREC and a few local growers. Thanks to Dave Carbaugh, Mark Sutphin, Rachel Marple, and Nick Leaverton for helping to collect and process the fruit. Please refer to my post from yesterday if you need help interpreting the different maturity indices. You can also download a pdf  of this data.

Golden Delicious Maturity Report 1986-2012

 

 
Year

Background Color (1-4)*

Firmness (lbs)

Soluble Solids (ºBrix)

Starch-iodine Index

(1-8)**

Ethylene (ppm)

Bloom Date

1986

2.2

19.5

12.7

1987

20.0

12.2

1988

18.6

11.0

1.5

1989

17.7

10.3

2.0

1990

18.0

10.5

1.6

1991

1.8

19.7

12.0

2.1

1992

1.8

20.1

12.0

1.6

1993

1.9

19.8

11.6

1.5

1994

2.3

19.8

12.0

1.7

1995

0.9

18.8

10.9

2.1

1996

2.9

19.6

11.2

2.9

1997

2.0

21.8

11.7

2.0

1998

2.5

19.2

12.2

2.1

1999

1.9

20.3

11.7

1.4

2000

1.8

17.5

11.9

2.5

2001

1.9

20.1

11.0

1.4

2002

2.2

21.2

11.4

2.1

2003

2.6

20.3

11.1

1.2

2004

2.3

18.2

12.3

2.0

2005

1.8

20.1

11.4

1.7

2006

1.9

18.5

12.4

1.8

2007

1.6

18.0

12.3

1.6

2008

2.1

18.3

12.9

1.6

22-23 Apr

2009

1.8

17.2

12.4

1.7

22-Apr

2010

1.6

18.6

12.9

1.4

13-Apr

2011

2.1

20.1

12.9

1.2

20-Apr

2012

2.5

18.5

12.5

1.3

0.00

2-Apr

Mean

2.0

19.2

11.8

1.8

16-Apr

Max

2.9

21.8

12.9

2.9

23-Apr

Min

0.9

17.2

10.3

1.2

2-Apr

* 1 = green, 2 = light green, 3 = yellowish green, 4 = yellow.
** 1 = 100% starch, 5 = 60% starch, 8 = 0% starch.

 


 


 

Red Delicious Maturity Report 1986-2012

Year

Red Color (%)

Firmness (lbs)

Soluble Solids (ºBrix)

Starch-iodine Index

(1-8)*

Ethylene (ppm)

Bloom Date

1986

72.0

18.8

11.2

1987

68.0

19.8

10.8

1988

54.0

18.4

10.0

1.6

1989

69.0

18.6

8.7

1.6

1990

73.0

18.1

8.9

1.5

1991

69.0

18.8

10.4

1.6

1992

76.0

20.8

10.2

1.3

1993

68.0

21.7

9.5

1.7

1994

68.0

19.7

9.5

1.9

1995

68.0

19.2

9.1

1.6

1996

62.5

19.3

8.9

2.0

25-Apr

1997

66.7

22.4

9.4

1.2

25-Apr

1998

81.9

19.3

9.9

2.5

15-Apr

1999

65.5

19.8

10.5

1.9

28-Apr

2000

87.4

16.2

9.6

2.3

11-Apr

2001

61.0

20.5

8.3

1.8

28-Apr

2002

60.2

21.4

9.4

2.1

22-Apr

2003

58.4

20.4

8.5

1.9

22-Apr

2004

88.2

16.7

10.0

2.3

20-Apr

2005

73.7

18.7

9.2

2.0

24-Apr

2006

63.8

18.7

10.7

2.0

16-Apr

2007

81.1

18.1

11.0

1.7

22-Apr

2008

86.6

18.1

9.4

2.0

22-Apr

2009

79.2

17.5

10.2

1.9

24-Apr

2010

65.9

18.2

11.5

1.7

8-Apr

2011

67.5

19.8

11.5

2.1

21-Apr

2012

92.5

18.2

11.9

1.8

0.03

29-30-Mar

Mean

71.4

19.2

9.9

1.8

19-Apr

Max

92.5

22.4

11.9

2.5

28-Apr

Min

54.0

16.2

8.3

1.2

29-30-Mar

* 1 = 100% starch, 5 = 60% starch, 8 = 0% starch.


 

Gala Maturity Report 2008-2012

 

 
Year

Red Color (%)

Firmness (lbs)

Soluble Solids (ºBrix)

Starch-iodine Index

(1-8)*

Ethylene (ppm)

Bloom Date

2008

93.5

18.3

13.6

5.6

21-Apr

2009

86.8

17.5

13.4

4.5

22-Apr

2010

78.0

16.3

14.9

6.4

9-Apr

2011

77.5

19.4

13.7

4.9

19-Apr

2012

91.1

18.0

13.2

4.1

7.13

29-30-Mar

Mean

85.4

17.9

13.8

5.1

14-Apr

Max

93.5

19.4

14.9

6.4

22-Apr

Min

77.5

16.3

13.2

4.1

29-30-Mar

* 1 = 100% starch, 5 = 60% starch, 8 = 0% starch.

 

Empire Maturity Report 2002-2012

 

 
Year

Red Color (%)

Firmness (lbs)

Soluble Solids (ºBrix)

Starch-iodine Index

(1-8)*

Ethylene (ppm)

Bloom Date

2002

42.0

25.3

10.4

2.1

2003

60.4

21.9

9.6

1.7

2004

78.1

17.2

10.9

2.2

2005

55.3

20.3

10.1

1.9

2006

46.0

19.7

10.7

2.1

2007

64.0

17.9

10.6

2.1

2008

66.3

18.2

11.0

2.1

21-Apr

2009

52.4

16.6

10.9

1.1

20-Apr

2010

44.3

18.1

10.7

1.8

2011

49.8

19.7

11.2

2.0

2012

85.9

19.2

12.5

1.7

0.01

29-Mar

Mean

58.6

19.5

10.8

1.9

13-Apr

Max

85.9

25.3

12.5

2.2

21-Apr

Min

42.0

16.6

9.6

1.1

29-Mar

* 1 = 100% starch, 5 = 60% starch, 8 = 0% starch.

 

Maturity Report – Other Varieties 2012

 

 
Variety

Red Color (%)

Firmness (lbs)

Soluble Solids (ºBrix)

Starch-iodine Index

(1-8)*

Ethylene (ppm)

Bloom Date

Fuji Early Strain

65.5

16.7

14.65

4.1

0.03

5-Apr

Fuji Late Strain

30.0

20.9

12.1

2.1

0.03

5-Apr

Ida Red

36.7

17.0

12.3

1.3

0.00

2-Apr

Rome

39.8

22.5

12.3

1.5

.

12-Apr

York

41.8

22.4

10.7

1

0.00

3-Apr

* 1 = 100% starch, 5 = 60% starch, 8 = 0% starch.

Harvest Maturity Resources

As we work our way through the 2012 harvest season, I’ve had several questions about maturity testing. Maturity testing helps growers plan their harvest scheduling to ensure optimal prices from buyers and, if desired, allow for the longest-term storability.

Here is a quick review of some of the different maturity indices that can be used for apples.

Starch-iodine test: As apples ripen, starch is converted to sugars. In the starch test, iodine binds with starch granules in the fruit and develops into a dark purple to almost black color. The less iodine development (less dark purple color) that you see, the more ripe the apple. Several visual rating scales have been developed to assist with understanding how to rate the various degrees of starch development. A commonly used starch index in the Eastern US was developed by Blanpied and Silsby and can be downloaded for free here: Predicting Harvest Date Windows for Apples. The color chart is located in the centerfold and is often referred to as the Cornell Starch-Iodine Chart (you can also download the below jpg file). Variety specific charts can be found through Google searches on the internet.

Pre-mixed iodine solution can be purchased through Wilson Irrigation in Yakima, WA. However, you can also make your own starch solution following either of the two recipes below:

Recipe 1: Purchase a 2% alcoholic solution of medicinal iodine from your local drug store and mix with an equal amount of water. (Purchasing the iodine at a drug store will be costly if you are going to need a lot of iodine solution during the harvest season.)

Recipe 2: Add 10 grams of potassium iodide and 2.5 grams of iodine crystals to 1 liter of distilled water. The solution may need to sit overnight before the iodine is fully dissolved. The reagents can be purchased through chemical suppliers such as Sigma-Aldrich or Fischer Scientific.

Store the iodine solution in an opaque container, or wrap the container with aluminum foil to prevent direct sunlight exposure. Sunlight will cause the iodine color to fade over time.

Growers and field managers who are visiting numerous orchards throughout the day often fill spray bottles with the iodine solution to conduct tests in the field. A 10-apple sample from a uniform block will usually suffice as long as proper sampling is conducted. Make sure to pick the samples from trees with an average crop load for that block and at a similar location on each tree to reduce within- and between-tree variability. The apples should be cut through the equator since apples do not ripen uniformly from stem- to calyx-end.

Soluble solid content: Soluble solids are measured in the unit •Brix and are a fairly close approximation for the total sugar content. You can find both handheld digital and optical refractometers through several sources, including QA Supply in Norfolk, VA and Wilson Irrigation in Yakima, WA.

Ethylene: In my lab, we use the internal ethylene method where a hypodermic needle is inserted through the calyx into the core cavity of an apple and a 1 cc gas sample is removed. This sample is analyzed by using a gas chromatograph (GC) that has been calibrated with known ethylene standards. As a rule of thumb, when apples are above about 1 ppm they are considered to have started the autocatalytic process known as climacteric ripening. Once apples begin this ripening process, they will increase many of the desirable eating characteristics (increased flavors, aromas, and sugars, and decreased firmness), but they will also begin to decrease in their capacity to maintain quality during long-term storage. Refrigeration, controlled atmosphere storage, AVG (ReTain), and 1-MCP (SmartFresh) will help to minimize additional ripening during storage. However, once the climacteric ripening process begins, it can not be reversed.

Firmness: Apples can be tested for firmness using a penetrometer. You can find handheld and bench-top instruments through several sources, including QA Supply in Norfolk, VA and Wilson Irrigation in Yakima, WA. While not an exact measure of maturity, firmness does decrease during the ripening process and is a very important apple quality parameter.

Size: For processing fruit, fruit size is often used to as a standard for quality. Many processors desire fruit to be a minimum of 2.75 inches, although market demands may influence that size standard. Sizes will also determine the packout and ultimately the value of the apples using USDA grading standards.

Red and background color: Many varieties have market standards for the percent of red surface or background green to yellow color needed to meet USDA grading standards. In general, cool nights will aid the development of color. Poor coloring strains of Red Delicious, Gala, and Fuji apples may need to be left on the tree for longer than their high coloring counterparts.

Flavor: Although we can use sophisticated instruments to quantify the concentration of individual flavor molecules in apples, the best measure is probably the human mouth. Always sample a few bites of your apples before picking to make sure they have the desired varietal characteristics. Picking good tasting fruit is important for all operations, but for those with direct marketing businesses, flavor might be the most important characteristic for determining harvest maturity.

As always, check with your buyer before picking so that you can ensure that you deliver to your customers the apples that will receive highest return.

I will share harvest maturity information for many of the commercially important apple cultivars found in the Winchester area at tonight’s Commercial Fruit Twilight Meeting and on this blog in a few days.

References

Blanpied, G.D. and K.J. Silsby. 1992. Predicting Harvest Date Windows for Apples. A Cornell Cooperative Extension Publication. Info. Bull. 221.

Anon. 1986. Apple Maturity Program Handbook. Washington State Apple Maturity Program. Wenatchee, WA.

Predicting harvest dates

With bloom being three to four weeks earlier than average this year, most tree-fruit crops are also being harvested earlier than usual. In a cherry trial that I have at the AREC, what few fruit survived the March 27 frost were harvested about three weeks ahead of last year. Likewise, we are picking peaches two to three weeks ahead of last year.

In our apple blocks, we are already seeing large fruit sizes for this time of year.

 

 

 

 

 

 

 

For apples, there are several prediction models that are used to estimate harvest dates. I used a model from Michigan State University that was published in HortTech by Randy Beaudry et al. (1993) to predict harvest maturity for apples.

The model predicts the first Red Delicious pick for Controlled Atmosphere (CA) storage, assuming that:

  • For this pick the desired starch is between 2.5-4 and the firmness is between 17-18 pounds.
  • There are 143 days between 80% full bloom and the first CA harvest
  • Deviations from 143 days are based upon the minimum temperatures for the 15 days after 80% full bloom. For each degree Fahrenheit change from 50F there is a 1 day plus or minus change in the harvest date.
  • For Winchester, using March 29 as the 80% full bloom date, the model is predicting August 27 as the date for the first CA harvest.
  • For Batesville, using March 29 as the 80% full bloom date, the model is predicting August 25 as the date for the first CA harvest.

(As a side note, it is interesting that both Winchester and central VA called March 29 the full bloom date. I choose the date for Winchester, and a grower choose the date for central VA.)

While the model isn’t perfect, when I ran data from 2011 and looked at harvest maturity indices, it was remarkably close. The model predicted Sept 10 as the harvest date; on Sept 12, Reds were at starch = 4.2 (8-pt scale), Brix = 13, and firmness = 17.9 lbs.

Since most growers have at least a few Reds, harvest dates for other varieties can be approximated. Otherwise, a rule of thumb is “for each 2-3 days departure for the normal bloom date, there will be a one-day departure from the normal harvest date.” Blanpied and Silsby (1992).

While there might be other factors that affect these predicted dates, especially given the oddities of this year, growers should be advised about the potential for such an early harvest. Some things to consider with an early harvest: the availability of labor when the fruit is ready to be picked, PHI, seasonal maximum rates for pesticides, and when to start applying stop-drop materials. I’ll talk more about stop-drop strategies when we meet at Cline’s Orchard and Graves Mountain Lodge in July.

Please let me know if any questions arise about this model or the predicted dates. Or, for that matter, horticultural questions in general.

Best regards,

Greg

References

Beaudry, R., P. Schwallier, and M. Lennington. 1993. Apple Maturity Prediction: An Extension Tool to Aid Fruit Storage Decisions. HortTechnology 3(2): 233-239.

Blanpied, G.D. and K.J. Silsby. 1992. Predicting Harvest Date Windows for Apples. Information Bulletin 221: A Cornell Cooperative Extension Publication, Ithaca, NY.