Tag Archives: apple

MaluSim Carbohydrate Model for May 12, 2014

Fruitlets in the Central Virginia area are quickly sizing up (reports are in the 12-18 mm range), and growers have only a couple-few more days to use NAA and 6-BA products for thinning. In the Winchester area fruitlets are just entering the 10 mm thinning window, but with the hot weather over the past few days it is likely that fruit will be growing at a rapid pace (greater than 0.5 mm per day).

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Table 1. Fruitlet sizes at the Alson H. Smith, Jr.AREC in Winchester.

Fruit diameter (mm)
Cultivar 12-May
Empire 10.4
Fuji 7.0
Gala 8.7
Goldens 8.0
Idared 8.1
Pink Lady 9.2
Red Delicious 8.0
York 7.9

In Central Virginia, the MaluSim model is showing a moderate carbohydrate deficit for the next three days, and then the carbohydrates balance shows positive values through the weekend.  A large deficit that was predicted to occur over the past weekend never materialized, largely because there was more sunlight than forecasted. Additionally, as the expanding leaf surface transitions from being a carbohydrate sink to a carbohydrate source the model will continue to show a positive carbohydrate balance. Growers should target blocks that require more aggressive thinning on Tuesday and Wednesday at normal or slightly reduced rates (unless trying to thin larger fruit) and then target blocks with lighter starting crop loads towards the end of the week.

In Winchester, bud break was 6 days later than in Central Virginia, meaning that many leaves are still sinks for carbohydrates and more severe deficits occured over the past few days.  However, as the Winchester area enters into the thinning window, less severe carbohydrate deficits are predicted to occur. Growers should start thinning their earliest blooming cultivars on Tuesday evening or Wednesday and then move to more lightly cropped blocks towards the end of the week and over the weekend.

Click below to download the full pdf reports:

Central VA MaluSim 5_12_14

Winchester VA MaluSim 5_12_14

MaluSim Carbohydrate Model for May 8, 2014

Slide3Due the rapidly changing weather forecasts, I ran the MaluSim model again on Thursday. For Central Virginia, the model is showing values in the -20 to 20 range for the next seven days. This means Slide3that growers should expect an “average” response from their chemical thinners.  Growers in the Central Virginia region should target the next couple-few days to make their thinning sprays as fruitlets are at the ideal size for applications of NAA and 6-BA. Fruitlets grow at ~0.5 mm/day in cool temperatures, and as you can see from the table below, up to 1 mm/day with warmer temperatures.

 

Table 1. Fruitlet sizes at Silver Creek Orchards.

1-Apr 28-Apr 30-Apr 2-May 6-May 8-May
Empire Silvertip Petal Fall 5.6 7.3 10.9 12.1
Red Delicious 5.7 6.5 9.3 10.6
Pink Lady 5.4 7.5 8.3 10.4
Gala 5.4 6.4 8.8 10.6
Fuji 4.4 5.8 7.8 9.9

Much warmer day and night temperatures are forecast for the Winchester area, so the MaluSim model is showing a persistent carbohydrate deficit for the next five days. However, we are still at petal fall to ~5 mm for most cultivars, so hopefully by the time fruit are at 10 mm more moderate weather conditions will reduce the chance of over thinning. Chemical thinning applications made when either the day-by-day or running average value is below -60 g CHO/day will likely result in aggressive thinning.

I will run the models again early next week. Please download the below pdf files for the full report.

Central VA MaluSim 5_8_14

Winchester VA MaluSim 5_8_14

 

MaluSim Carbohydrate Model for May 6, 2014

Today, I ran the MaluSim model for both Central Virginia <pdf> and  Winchester <pdf>.

Central VA MaluSim 5_6_14 Winchester MaluSim 5_6_14

For Central Virginia, fruitlets are just starting to approach the 10 mm stage. It looks like the best chance to get a strong thinning response will be Wednesday and Thursday. After that, the model is showing that chemical thinners will have more of an “average” response. Target blocks that have a heavy crop load on Wednesday and Thursday, and leave blocks with more frost damage and lighter crop loads to thin on Friday and over the weekend.

 

 

 

 

 

Table 1. Fruitlet sizes at Silver Creek Orchards.

1-Apr 28-Apr 30-Apr 2-May 6-May
Empire Silvertip Petal Fall 5.6 7.3 10.9
Red Delicious 5.7 6.5 9.3
Pink Lady 5.4 7.5 8.3
Gala 5.4 6.4 8.8
Fuji 4.4 5.8 7.8

For the Winchester area, most blocks are at petal fall or just beyond. We’re forecasted to have some summer-like weather over the next several days, which will cause a fairly strong carbohydrate deficit in the trees. Petal fall thinning sprays rarely over thin, even in hot weather, however blocks with fruitlets approaching 10 mm may see a strong thinning response from applications made over the next three to four days.

I will run another set of models on Friday. I will also start posting fruitlet sizes from fruit at the AREC. Download the above linked pdf files to view the full reports.

Fruit Bud Damage from Cold Temperatures

Cold temperatures in the winter, such as we’re experiencing over the next couple-few days with a polar vortex can cause damage to plants, people, and livestock. Tmin forecast 1_6_14_midatlanticAt this time of year, fruit buds on our main tree-fruit crops (apple, peach, cherry, and pear) are still in their winter dormant state (endodormancy). During endodormancy, buds have a very low water content and tend to be more cold tolerant. However, absolute lows are not the only factor to consider. If warm temperatures precede a cold spell, then tree buds tend to be less cold tolerant and are more likely to be damaged. There is also considerable variation amongst species and cultivars. For this reason, critical temperature thresholds, like those developed for spring frost damage to flower buds, are not well defined. However, from an ongoing discussion among pomologists in the Eastern part of North America, the consensus seems to be that peach flower buds start to be damaged at -10F and complete crop failure and/or tree loss occurs at -20F. Cherry and plum flower buds are slightly more cold hardy than peach buds and damage will likely occur at -20F. Apple flower buds can withstand temperatures down to -25F. As of now, the forecast for most of Virginia does not show temperatures dropping below 0F. Hopefully, this means that fruit buds in Virginia will not be damaged by the polar vortex.

Plants are not affected by wind chills (plants do not lose heat to the wind). But people and animals will be impacted by the heat loss from the high winds that are accompanying this storm. I’ve seen several wind chill forecasts for Tuesday in the -10 to -20F range. If your pruning crews are outside, make sure they are dressed appropriately for the cold. Also, make sure that your farm animals at least have shelter from the wind. For more information on protecting farm animals and equipment from the cold, read Cory Childs’ (VCE-Warren Co.) blog post from earlier today.

 

 

Harvest Maturity Report for September 23

On Monday, September 23, we collected Rome, York, Fuji, and Stayman apple samples for this week’s maturity report (2013 Sept 23 Maturity Report). The weather in the northern Shenandoah Valley will remain cool, with clear sunny days for the next week. These conditions are continuing to promote excellent fruit color and varietal flavors, while also extending the harvest window for many cultivars.

Of the fruit we measured this week, Rome harvest should be starting soon (starch = 3.3; ethylene <1.0), while the main Fuji harvest crop will probably not be ready to pick until next week at the earliest. Staymans and Yorks still have very high firmness (>18.8 and 23.6 lbs, respectively) and very low ethylene (<1.0) and starch degradation (=1), indicating that it will be several more weeks until they will be physiologically mature enough for harvest.

Golden Delicious harvest is concluding for many growers, though fruit that is still on the trees has maintained a high level of quality. For a pre-harvest drop test, we did a large Red Delicious sampling late last week, and we will do another one next week. Red Delicious harvest is still ongoing, with many strains still viable for long-term storage and SmartFresh applications.

As always, due to location, rootstock, strain, and environmental factors, fruit in your orchards may be at a different maturity than the fruit at the AREC. For this reason, you should be checking blocks several times a week to ensure that you harvest at your desired maturity. More information about harvest maturity indices can be found at my post from last year.

Harvest Maturity Report for September 16

On Monday, September 16, we harvested Red Delicious, Golden Delicious, Empire, Idared, Rome, and Fuji BC2 (a late ripening strain) for this week’s Maturity Report. Based on the apples that we harvested at the AREC, Goldens are moving past the point where they should be harvested for long term storage. Reds are still OK for long term storage, but a few of the Red Delicious apples that we tested had very advanced maturity. Empires are eating well and should be picked soon. Earlier ripening blocks of Romes and Idared should be checked as they are starting to ripen at the AREC. We’re looking to start our Fuji harvest late next week.

Besides for a chance of showers over the weekend, the forecast for the next week continues  to look excellent for harvest.

Harvest Maturity Report for September 10

We harvested apples on September 10 for this week’s harvest maturity. Due to our annual Field Day and running samples for a pre-harvest drop trial, we only ran Golden Delicious, Red Delicious, and two strains of Fuji. From these data and my observations from around Frederick County, it appears that sugar content (soluble solids) are starting to come up in Golden Delicious, while starch degradation is still optimal for long term storage. Red Delicious are starting to ripen, and some early coloring strains are already being picked. I expect Red Delicious harvest to be in full swing by early next week. Early strains of Fuji are ready for harvest, but later strains still have several weeks before they will be ready for harvest. On Thursday, we’ll be harvesting Daybreak Fuji from a tall spindle planting and Rising Sun Fuji from a rootstock trial.

I expect the heat over these past couple-few days will advance apple ripening faster than what we have seen up until this time, so keep checking blocks that are near to your ideal harvest maturity. The heat is forecasted to break on Friday after which we’ll return to more moderate temperatures for at least seven days.

Click the link to the right for this week’s harvest maturity evaluation data.

Harvest Maturity Report for September 3

We collected fruit on Tuesday for this week’s maturity testing. Most growers in the Winchester area are finished or near to finishing Honeycrisp and Galas and moving into the main cultivars. Golden Delicious harvest has started, but the fruit has not advanced in maturity very much over the past week and is still very variable based on location and planting system. Compared to last week, the Goldens have lost firmness, but not starch and they have not increased in soluble solids or ethylene. Most Red Delicious strains are still at least a week away from early harvests for long term storage. This is despite the deep red colors that are developing. Picking of early strains of Fuji is underway, and like the other red skinned cultivars appear to have very nice color and size this year. Empires are starting to ripen and can probably be picked sometime in the next week, particularly if the fruit is going to be stored for any significant amount of time.

Over the next week, we are going to remain in a relatively dry weather pattern with warm but not hot days in the 80s and cool nights in the 50s and 60s. These conditions are ideal for developing color on red skinned cultivars and allowing the fruit to hang on the tree until ideal maturity and flavor has developed. We can only hope that these conditions will continue for several more weeks.

Click on the below link to download a pdf of the complete harvest maturity report for September 3, 2013.

2013 Sept 3 Maturity Report

Annual End-of-August Maturity Testing

This it the 28th year that 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. Including 2013, data for Empire has been taken for twelve years and Gala for six years. In recent years, we have also 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.

As discussed in a previous post, bloom date was about three weeks later than in 2012 and fairly close to the long-term averages. This should mean that harvest dates will be relatively “normal” or at least more similar to harvest dates in the late 1990’s through early 2000’s than they have been in the last several years.

As of this week, most growers in the Northern Shenandoah region are finishing up picking Ginger Golds, and have started picking Gala and Honeycrisp. Some growers in Central Virginia are finishing Gala and starting with Golden Delicious.

Many of the Golden Delicious blocks that we tested this week had very nice fruit finish, with minimal russet. Golden Delicious maturity was quite variable in the blocks that we tested, and it appears that some blocks will be ready to harvest within the next week, while others are probably 7-10 days away from being ready to harvest. The use of ReTain by some growers may explain some of this variability.

With the cool nights that we have experienced in August, red skinned cultivars have developed better than average color. However, be sure to check the starch and sugar levels before picking to be sure that the apples are mature enough to pick. Many Red Delicious apples that we tested this week had great color but very little starch degradation and soluble solids were only at 9-10 Brix.

Below are the data from this year’s end-of-August apple maturity sampling. In each year, the samples were taken around August 25 (August 26 this year) and consist of apples from the AREC and a few local growers. Thanks to Dave Carbaugh and Abby Kowalski for collecting and testing the fruit. Please refer to my post from last year if you need help interpreting the different maturity indices. You can also download a pdf of the 2013 Annual August Maturity Report.

Golden Delicious Maturity Report 1986-2013

 

 
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

13.0

1.3

0.00

2-Apr

2013

2.2

18.3

11.9

2.2

0.17

25-Apr

Mean

2.0

19.2

11.9

1.8

17-Apr

Max

2.9

21.8

13.0

2.9

25-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 1986-2013

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

92.1

18.2

11.9

1.8

0.03

29-30-Mar

2013

91.3

18.4

9.8

2.0

0.25

23-Apr

Mean

72.1

19.1

9.9

1.8

0.1

20-Apr

Max

92.1

22.4

11.9

2.5

0.3

28-Apr

Min

54.0

16.2

8.3

1.2

0.0

29-30-Mar

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

 

Gala Maturity Report 2008-2013

 

 
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

2013

91.1

18.0

12.4

5.4

1.71

23-Apr

Mean

86.3

17.9

13.5

5.2

4.4

15-Apr

Max

93.5

19.4

14.9

6.4

7.1

23-Apr

Min

77.5

16.3

12.4

4.1

1.7

29-30-Mar

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

 

Empire Maturity Report 2002-2013

 

 
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

2013

63.0

18.6

10.6

1.5

0.04

21-Apr

Mean

59.0

19.4

10.8

1.9

0.0

15-Apr

Max

85.9

25.3

12.5

2.2

0.0

21-Apr

Min

42.0

16.6

9.6

1.1

0.0

29-Mar

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

 

Maturity Report – Other Varieties 2011

Cultivar

Red Color (%)

Firmness (lbs)

Soluble Solids (ºBrix)

Starch-iodine Index (1-8)*

HoneyCrisp

66.2

15.8

13.0

5.1

Idared

17.0

19.9

11.1

1.2

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

Maturity Report – Other Varieties 2012

 

 

Cultivar

Red Color (%)

Firmness (lbs)

Soluble Solids (ºBrix)

Starch-iodine Index (1-8)*

Ethylene (ppm)

Bloom Date

Fuji Early Strain

65.5

16.7

14.7

4.1

0.03

5-Apr

Fuji Late Strain

26.0

20.9

12.1

2.1

0.03

5-Apr

Idared

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

0.00

3-Apr

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

Maturity Report – Other Varieties 2013

 

 

Cultivar (number of orchards tested)

Red Color (%)

Firmness (lbs)

Soluble Solids (ºBrix)

Starch-iodine Index (1-8)*

Ethylene (ppm)

Bloom Date

Cameo (1)

33.5

18.1

10.2

1.7

0.53

N/A

Fuji Early Strain (2)

80.3

16.3

13.6

4.3

1.51

25-Apr

Ginger Gold (2)

3.9**

16.0

12.8

3.5

0.00

24-Apr

Idared (6)

41.1

17.5

10.1

1.2

0.12

23-Apr

Jonagold (1)

35.5

18.7

11.8

2.8

0.00

23-Apr

Rome (1)

21.2

24.6

9.2

2

0.00

1-May

York (1)

53.5

24.4

9.4

1

1.20

25-Apr

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

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.