Apple Maturity Assessments

Routine measurements of fruit starch levels, ground color and other maturity indices allow growers to make improved decisions about optimum harvest dates for long-term storage. During August through the end of October, 2017, this site will be updated weekly with both tables and photos that demonstrate progressions in apple maturity.

The Mid-Atlantic apple industry is going through a number of dramatic changes due to the planting of high density orchards with newer cultivars. These transitions, coupled with climate and weather changes, make it difficult for growers to predict optimum fruit maturity for long-term storage.

To track developments in physiological maturity, we will measure starch pattern, firmness, soluble solids, fruit size, % red color and ground color changes (visually and with a Delta A meter). The cumulative data will be presented here, and summaries of Starch Pattern Index and Delta A values will be posted each week at Fruit Times. The starch index measures the loss of starch in the flesh, while Delta A values are being evaluated as a measure of changes in ground color.

Our working hypothesis is that ethylene--sometimes referred to as the fruit ripening hormone--increases as fruit mature, leading to the coordinated ripening of apples. Ethylene initiates new enzyme production in fruit that affects visible attributes like surface color and ground color, as well as hidden attributes like starch pattern index, flesh firmness and soluble solids.

The project is supported by the State Horticultural Association of Pennsylvania Research Committee and is a cooperative effort of University of Maryland Extension and Penn State Extension.

Subscribers to the electronic version of Fruit Times will receive the weekly reports by emails easily read on a smart phone. If you receive the paper copy of Fruit Times, visit your library for the weekly updates that will be posted at Penn State Extension Tree Fruit Production. To sign up for electronic updates, visit Subscribe to Our Email List.

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2019 Apple Maturity Assessments

Apple Maturity Assessments: Week 1

In the Mid-Atlantic region growers have either begun—or expect to soon begin, picking Premier Honeycrisp.

UPDATED: AUGUST 2, 2019

2019 Apple Maturity Assessments: Week One

Red-colored Premier Honeycrisp apples spot picked in Pennsylvania earlier this week. Photo: Chris Walsh, University of Maryland

The red-colored Premier Honeycrisp apples we spot picked in Pennsylvania earlier this week (Figure 1) represented a very small fraction of the crop on these trees. These fruit were large with 43% red color and yellowish-green to greenish-yellow ground color. These apples were slightly acidic, had low soluble solids (sugar) but had softened and lost a significant amount of starch.

In the July 31, 2019 edition of the Washington Post, it was reported that July temperatures at Reagan National Airport were 2.3°F greater than the thirty-year average for the month. This has been going on all year as the first seven months of 2019 were 2.6°F warmer than the thirty-year average. Weather forecast for the first ten days of August predicted cooler weather. Will that cooler weather last for the rest of August, or will the warm wet weather of August 2018 return? Hopefully, it won’t, as the 2018 weather led to rain cracking and an increase of storage rots.

In late July, we started apple maturity sampling in Adams County, focusing on a tall-spindle Premier Honeycrisp planting at a 900-foot elevation near Gettysburg (Figure 1). Fruits were spot-picked for size and color. While there was not yet adequate red color at this site, tree ripening on a few Premier Honeycrisp fruit had begun. Growers we talked with planned a light spot-picking this weekend.

Since we are evaluating fruit from just one orchard, our results should only be used as a guide. Of course, maturity varies greatly between orchards and even between blocks in the same orchard. That makes it important for you to follow these weekly reports but also continue to conduct your own maturity tests.

The following table shows data from pre-harvest apple samples taken on July 31, 2019.

Cultivar Date Diameter (inches) Red Color (%) Ground Color Firmness (pounds) Starch Pattern (1 – 8) Soluble Solids (°Brix)
Premier Honeycrisp July 31, 2019 3.4 43 *YG to GY 13.6 4.7 11.3
Buckeye Gala July 31, 2019 2.8 45 YG 20.8 2.1 10.9

*YG = Yellowish Green; GY = Greenish Yellow

Red color development in apples depends on light, temperature, and fruit physiology. In warmer weather, growers have to wait to pick until red color development is enhanced by ethylene production during maturation and tree ripening. By the time this happens, the fruit are more mature and have also lost starch and flesh firmness, which will shorten their storage life.

As our plantings of August apples have increased, growers report problems juggling Gala and Honeycrisp harvest. This week we are also reporting Buckeye Gala maturity data. Next week we will add Pacific Gala and Honeycrisp from the same location. These data should provide growers with an idea of the relative maturity of these valuable early varieties to help schedule their harvest.

Apple Maturity Assessments: Week 2

With mid-summer heat, Premier Honeycrisp apples in the Mid-Atlantic region are maturing rapidly. The fruit we spot-picked that had 50% red color had lost most of their starch and were softening.

UPDATED: AUGUST 9, 2019

2019 Apple Maturity Assessment: Week Two

Photo: Chris Walsh, University of Maryland

We also noticed that these apples were quite loose and easy to pick. While the apples still tested low in soluble solids and were slightly acidic, their size and crispness should make them easy to market.

This is our second week of maturity sampling in Adams County. We are focusing on four apple varieties: Premier Honeycrisp, Buckeye Gala, Pacific Gala, and Honeycrisp. Fruits were spot-picked for size and color and then taken to the laboratory in College Park, Maryland, for analysis.

Range of color on Premier Honeycrisp. Photo: Chris Walsh, University of Maryland

This week we added laboratory measurements to quantify ground color. We measured chlorophyll levels in the peel (Figure 1) and reported the results as the Delta A value. As the ground color changes from green to yellow, chlorophyll is lost in the peel and the Delta A value decreases. This week our spot-picked Premier Honeycrisp apples had 52.5 percent red color, a greenish-yellow ground color, and Delta A values of 0.52. They had also softened to 12.6 pounds.

Figure 1. Measuring ground color with a Delta A meter. Photo: Chris Walsh, University of Maryland

Honeycrisp and Premier Honeycrisp are unusual as they are crisp but soft. Why? Our perception of crispness comes with the first bite with our incisors. Firmness measurements with a penetrometer (or pressure tester) after the peel is removed reflect the feeling of chewing with our molars. Red color development in apples depends on sunlight, temperature, and fruit development. In hot weather, growers have to delay picking until red color development is triggered by ethylene during fruit maturation and tree-ripening. In the case of Premier Honeycrisp, much of the red color development is likely driven by this tree-ripening process.

In the mid-Atlantic region, the local acreage of August apples has increased. As a result, growers have recently had problems juggling Gala and Honeycrisp harvests. Last week we only reported data for Premier Honeycrisp and Buckeye Gala. This week we added Pacific Gala and Honeycrisp from the same location to provide a better idea on the relative maturity of these important August varieties.

While we have been watching Premier Honeycrisp mature rapidly, the maturation of Buckeye Gala and Pacific Gala has been slower. Spot-picked fruit of both Galas increased in size and red color. They have also begun to lose starch and firmness. While they are losing starch, they have not increased in soluble solids (sugar). As we tested these Galas, we also noticed a number of the smaller fruit were seedless. Based on these observations, the Gala harvest is likely to begin at this orchard “on time” during mid-August.

Since we are evaluating fruit from just one orchard, our results should only be used as a guide. Of course, maturity varies greatly between orchards and even between blocks in the same orchard. That makes it important for you to follow these weekly reports and also continue to conduct your own maturity tests.

The following table shows data from pre-harvest apple samples taken on July 31 and August 5, 2019.

Cultivar Date Diameter (inches) Red Color (%) Ground Color Visual Ground Color (Delta A) Firmness (pounds) Starch Pattern (1 – 8) Soluble Solids (°Brix)
Premier Honeycrisp                
  July 31, 2019 3.4 43 YG to GY 0.78 13.6 4.7 11.3
  August 5, 2019 3.4 52.5 GY 0.52 12.6 6.1 12
Honeycrisp                
  July 31, 2019 3.2 3.8 LT G 1.52 17.4 1 10.8
  August 5, 2019 3.2 7.5 LT G 1.49 17.2 1.3 11
Buckeye Gala                
  July 31, 2019 2.8 45 YG 1.2 20.8 2.1 10.9
  August 5, 2019 2.8 52.5 GY 1.1 19.2 3.7 10.6
Pacific Gala                
  July 31, 2019 2.8 15 YG 1.29 21.5 1.7 10.9
  August 5, 2019 2.8 25 YG 1.16 20.3 2.8 10.5

G = Green: LTG = Light Green; YG = Yellowish-Green; GY = Greenish-Yellow: LTY = Light Yellow

Red color development in apples depends on light, temperature, and fruit physiology. In warmer weather, growers have to wait to pick until red color development is enhanced by ethylene production during maturation and tree ripening. By the time this happens, the fruit are more mature and have also lost starch and flesh firmness, which will shorten their storage life. (Figure 2)

Figure 2. Red color development and tree-ripening of Premier Honeycrisp apples during the first week of August. Spot-picked apples with greater than 50 % red color had lost most of their starch. Photo: Chris Walsh, University of Maryland

Apple Maturity Assessments: Week 3

Both Buckeye Gala and Pacific Gala have begun maturing. Visible changes in ground color and red color were seen this week.

UPDATED: AUGUST 16, 2019

2019 Apple Maturity Assessments: Week Three

Photo: Chris Walsh, University of Maryland

A slight change in firmness and soluble solids was also noted, while the change in the starch pattern was much more dramatic. Starch was absent in the core of these spot-picked fruit and had begun to disappear in the flesh. Although the Gala were too small to bring a premium price, the visible red color, starch pattern index, and varietal flavor were evident. While still small, they now appear to be mature enough for long-term storage.

Buckeye Gala and Pacific Gala

Next week’s predicted heat wave will slow red color development and fruit growth. Watch your Gala blocks closely next week. Once they lose a little more starch and tree ripen, they become susceptible to stem-end cracking and then lose marketability, storage life, and shelf life. This week we noted a considerable loss of starch in the flesh (Figure 1). We also found a similar starch staining pattern in Brookfield Gala picked at a different orchard in Washington County, Maryland.

Gala is an unusual early apple as it produces lower amounts of ethylene during maturation. This is atypical for an August apple. Ethylene increases much more slowly in Gala than MacIntosh or Honeycrisp. Consequently, Galas are less likely to drop, but they can become mealy while still attached.

To minimize harvest overlap, watch your Galas closely to ensure late-picked Gala apples do not become overripe once Honeycrisp harvest begins. Premier Honeycrisp and Honeycrisp harvests are about three weeks apart. Galas are usually ready during the latter half of those three weeks. To avoid a stressful harvest and loss of Gala fruit quality, don’t let Galas become overripe when Honeycrisp picking begins.

 

The following table shows data from pre-harvest apple samples taken on July 31 and August 13, 2019.

Cultivar Date Diameter (inches) Red Color (%) Ground Color Visual Ground Color (Delta A) Firmness (pounds) Starch Pattern (1 – 8) Soluble Solids (°Brix)
Premier Honeycrisp                
  July 31, 2019 3.4 43 YG to GY 0.78 13.6 4.7 11.3
  August 5, 2019 3.4 52.5 GY 0.52 12.6 6.1 12
  August 13, 2019 3.6 53.8 LTY 0.35 11.2 7.2 13.5
                 
Honeycrisp                
  July 31, 2019 3.2 3.8 LTG 1.52 17.4 1 10.8
  August 5, 2019 3.2 7.5 LTG 1.49 17.2 1.3 11
  August 13, 2019 3.3 15 LTG 1.2 15.8 2.5 12.3
                 
Buckeye Gala                
  July 31, 2019 2.8 45 YG 1.2 20.8 2.1 10.9
  August 5, 2019 2.8 52.5 GY 1.1 19.2 3.7 10.6
  August 13, 2019 2.9 67.5 LTY 0.69 17.4 5 11.3
                 
Pacific Gala                
  July 31, 2019 2.8 15 YG 1.29 21.5 1.7 10.9
  August 5, 2019 2.8 25 YG 1.16 20.3 2.8 10.5
  August 13, 2019 3 47.5 WY 0.61 17.8 5.4 12.2

G = Green; LTG = Light Green; YG = Yellowish Green; GY = Greenish Yellow; LTY = Light Yellow; WY = Whitish-Yellow

Premier Honeycrisp

We sampled Premier Honeycrisp just before the crew began their third spot picking in our sampling area. Cooler weather in early August and a few nights in the 50s had triggered red color. Fruit size had increased as well, and almost all starch had been lost in the Premier fruit (Fig 2). They had some varietal flavor, crispness, and excellent size. With an average weight of 308 grams and 3.6 inches in diameter, it would take about 56 fruit to fill a 38-pound box. The same calculation last week would have estimated 66 fruit in a 38-pound box.

Premier Honeycrisps grow fast as they tree ripen. This was a three percent per day gain in fresh weight. This is not quite as great as the “final swell” in peaches, but it is still notable.

Figure 2. Color, size, and starch staining pattern of Premier Honeycrisp spot-picked on August 13, 2019. Photo: Kathy Hunt, University of Maryland

Apple Maturity Assessments: Week: 4

Hot weather continues to push early-season apples to ripen ahead of ‘normal.’ Premier Honeycrisp harvest is completed in much of the mid-Atlantic region while picking Gala, Honeycrisp and Daybreak Fuji will begin soon.

UPDATED: AUGUST 22, 2019

2019 Apple Maturity Assessments: Week Four

Photo: Kathy Hunt, University of Maryland

These three varieties are all maturing very quickly, responding to our warmer than average summer temperatures. The limited shading and cooling afforded to fruit grown in tall-spindle orchards further magnifies the effect of hot weather on fruit maturity.

Gala harvest will begin soon in Southern Pennsylvania. With the heat, you may be tempted to wait for increased fruit size and red color development in Gala. Be aware that waiting for those qualities that improve marketability can also decrease storage life and shelf life, and increase the potential for Gala fruit cracking before it is harvested.

Buckeye Gala and Pacific Gala

We noted dramatic changes in Gala fruit maturity when we spot picked this week. Red color increased from 67 percent last week to 76 percent this week. Ground color also changed, with spot-picked fruit now a whitish-yellow. Gala apples continued to soften, lose starch, and increase in sugar. Their soluble solids increased to 12.7° Brix.

Stem-end cracking is one of the most important disorders affecting Gala packout (Fig 1). Cracking occurs as the fruit starch is broken down into hexose sugars. This additional sugar pulls water into the fruit which cracks at weaker, russeted spots in the stem-end basin. While the cracks start at about ½ inch in length, continued softening followed by a heavy rain lengthens the crack from the stem end to the calyx end of the fruit.

Our past experience showed that cracking could occur once the starch pattern index reaches six on the Cornell chart. While we did not see any stem-end cracking in the Gala fruit sampled a week ago, cracking was evident this week. We noted 19 percent of Buckeye Gala fruit with cracking and 17 percent with stem-end cracks in Pacific Gala. As expected, there was little starch left in these cracked Gala apples. The starch pattern index of cracked Gala fruit averaged more than 6.0.

While fruit with small shoulder cracks can be sold at local markets, be aware that significant rainfall on tree-ripe fruits can lead to severe cracks that can render the fruit unsaleable.

 

The following table shows data from pre-harvest apple samples taken from July 31 until August 19, 2019.

Cultivar Date Diameter (inches) Red Color (%) Ground Color Visual Ground Color (Delta A) Firmness (pounds) Starch Pattern (1 – 8) Soluble Solids (°Brix)
Premier Honeycrisp                
  July 31, 2019 3.4 43 YG to GY 0.78 13.6 4.7 11.3
  August 5, 2019 3.4 52.5 GY 0.52 12.6 6.1 12
  August 13, 2019 3.6 53.8 LTY 0.35 11.2 7.2 13.5
  August 19, 2019 Harvest Complete            
Honeycrisp                
  July 31, 2019 3.2 3.8 LTG 1.52 17.4 1 10.8
  August 5, 2019 3.2 7.5 LTG 1.49 17.2 1.3 11
  August 13, 2019 3.3 15 LTG 1.2 15.8 2.5 12.3
  August 19, 2019 3.4 37.5 YG to GY 0.83 13.2 6.2 12.5
Buckeye Gala                
  July 31, 2019 2.8 45 YG 1.2 20.8 2.1 10.9
  August 5, 2019 2.8 52.5 GY 1.1 19.2 3.7 10.6
  August 13, 2019 2.9 67.5 LTY 0.69 17.4 5 11.3
  August 19, 2019 3.2 76.3 WY 0.47 16 5.9 12.7
Pacific Gala                
  July 31, 2019 2.8 15 YG 1.29 21.5 1.7 10.9
  August 5, 2019 2.8 25 YG 1.16 20.3 2.8 10.5
  August 13, 2019 3 47.5 WY 0.61 17.8 5.4 12.2
  August 19, 2019 3 43.8 WY 0.42 16 5.9 12.5
Daybreak Fuji                
  August 19, 2019 3.1 43.8 GY 0.74 17.5 4.8 15.6

G = Green; LTG = Light Green; YG = Yellowish Green; GY = Greenish Yellow; LTY = Light Yellow; WY = Whitish Yellow

Premier Honeycrisp and Honeycrisp

Premier Honeycrisp harvest in our sampling orchard near Gettysburg ended last week. A couple of cold nights increased red color development in Honeycrisp, while the hot days that followed increased internal maturity. Our spot-picked Honeycrisp apples had 37 percent red color, 13 pounds firmness, 12.5° Brix, and a starch pattern index of 6.2 (Fig 2). While they are now maturing, few of these spot-picked Honeycrisp had varietal flavor.

In 2018 we noticed a number of very small cracks in the shoulder region of Honeycrisp fruit as they were tree-ripening. These cracks would not affect direct marketers but did damage stored fruit as they became entry points for postharvest rots.

Figure 2. Color, size, and starch staining pattern of Honeycrisp spot-picked on August 19, 2019. Fruit that had lost all their starch (the three on the right side of the photo) were developing varietal flavor. Photo: Kathy Hunt, University of Maryland

Daybreak Fuji

Daybreak Fuji is typically harvested in early to mid-September. In our 2018 maturity studies, fruit were tree-ripe about two weeks earlier than the normal picking date. Soft, tree-ripe Daybreak Fuji fruit did not store well in 2018. As Daybreak Fuji was particularly responsive to last year’s hot weather, we added that variety to our trials this week. Daybreak Fuji fruit we spot-picked were mature. They had developed some varietal flavor, softened to 17.5 pounds firmness, lost some starch with a pattern index of 4.8, and measured a surprising 15.6° Brix.

How do temperatures actually affect fruit development? A good rule of thumb is that fruit respiration doubles for every increase in temperature of 18°F (10°C). This is called the temperature coefficient or Q10. While cool nights stimulate red color development, they also slow fruit development. Warm temperatures increase fruit respiration and biological activity, which reduces starch loss, increases soluble solids, and increases the rate of softening.

In addition to measuring visible and hidden attributes of quality and maturity, we have also been monitoring ethylene evolution (Fig 3). Ethylene is the primary plant hormone driving many of the changes that occur during fruit maturation and ripening. We are particularly interested in comparing ethylene evolution in Gala and Honeycrisp. Honeycrisp’s high level of ethylene production is characteristic of early-season varieties which are prone to fruit drop. Gala apples have a very strong parent-plant inhibition of ethylene production. This reduced ethylene production reduces preharvest fruit drop. Consequently, unpicked Gala fruit routinely hang on the tree until after they are overripe.

Apple Maturity Assessments: Week 5

Hot weather along the Mason-Dixon Line continues to push early-season apples to mature and ripen rapidly.

UPDATED: AUGUST 30, 2019

2019 Apple Maturity Assessments: Week Five

Photo: Kathy Hunt, University of Maryland

Within the last week, many growers rushed to complete harvest of Gala and Honeycrisp. Daybreak Fuji, one of the most heat-responsive varieties we’ve tested, was also maturing. Despite limited red color, growers have begun spot-picking that crop ahead of schedule as Daybreak fruit were softening and tasted sweet.

Gala

Gala harvest is in full swing in Southern Pennsylvania. In the past week, fruit at our maturity test site near Gettysburg continued to soften, lose starch, and increase in soluble solids. Gala has proven to be an unusual early-season apple with its heat tolerance. This year, with hotter weather in Virginia, Maryland, and Southern Pennsylvania it has softened quickly. Even with AVG (ReTain) treatment, growers are seeing Gala fruit rapidly tree-ripen.

Buckeye Gala at our test site were tree-ripe when they were picked. In the past two weeks, red color developed significantly. In that same period firmness decreased by two pounds to 15.5 lb, while soluble solids increased two degrees to 13.3° Brix.

While this increase in fruit quality was good, it was not without its drawbacks. We are always concerned that tree-ripe Gala apples are susceptible to stem-end cracking. As the starch is lost, stem-end cracking increases. In our small sample, fruit with a starch pattern index (SPI) of 6 had 16% stem-end cracks; those with an SPI of 7 had 22% cracking, and those with an SPI of 8 had 84% cracking.

With hurricane season ahead, be sure to monitor your Gala crop. Heavy rains on tree-ripe Galas can lead to disastrous on-tree cracking, as shown in Figure 1.

The following table shows data from pre-harvest apple samples taken from July 31 until August 27, 2019.

Cultivar Date Diameter (inches) Red Color (%) Ground Color Visual Ground Color (Delta A) Firmness (pounds) Starch Pattern (1 – 8) Soluble Solids (°Brix)
Premier Honeycrisp                
  July 31, 2019 3.4 43 YG to GY 0.78 13.6 4.7 11.3
  August 5, 2019 3.4 52.5 GY 0.52 12.6 6.1 12
  August 13, 2019 3.6 53.8 LTY 0.35 11.2 7.2 13.5
  August 19, 2019 Harvest Complete            
Honeycrisp                
  July 31, 2019 3.2 3.8 LTG 1.52 17.4 1 10.8
  August 5, 2019 3.2 7.5 LTG 1.49 17.2 1.3 11
  August 13, 2019 3.3 15 LTG 1.2 15.8 2.5 12.3
  August 19, 2019 3.4 37.5 YG to GY 0.83 13.2 6.2 12.5
  August 27, 2019 3.5 55 LTY 0.66 13.1 6.6 13.6
Buckeye Gala                
  July 31, 2019 2.8 45 YG 1.2 20.8 2.1 10.9
  August 5, 2019 2.8 52.5 GY 1.1 19.2 3.7 10.6
  August 13, 2019 2.9 67.5 LTY 0.69 17.4 5 11.3
  August 19, 2019 3.2 76.3 WY 0.47 16 5.9 12.7
  August 27, 2019 3 75 WY 0.33 15.5 7 13.3
Pacific Gala                
  July 31, 2019 2.8 15 YG 1.29 21.5 1.7 10.9
  August 5, 2019 2.8 25 YG 1.16 20.3 2.8 10.5
  August 13, 2019 3 47.5 WY 0.61 17.8 5.4 12.2
  August 19, 2019 3 43.8 WY 0.42 16 5.9 12.5
  August 27, 2019 3.1 55 WY 0.34 14.8 6.8 13.7
Daybreak Fuji                
  August 19, 2019 3.1 43.8 GY 0.74 17.5 4.8 15.6
  August 27, 2019 3 68.8 LTY 0.68 16.8 6.5 16.1

G = Green; LTG = Light Green; YG = Yellowish Green; GY = Greenish Yellow; LTY = Light Yellow; WY = Whitish Yellow

Honeycrisp

While there have been some cooler nights recently, the above-average temperatures in the mid-Atlantic region have accelerated Honeycrisp ripening. This week our spot-picked Honeycrisp apples had 55 percent red color, 13.1 pounds firmness, 13.6° Brix, and a starch pattern index of 6.6 (Figure 2). While the red color increased almost 20 percent in these fruit during the past week, firmness, soluble solids, and starch pattern index were similar to those measured a week earlier. They were tree-ripe with varietal flavor, and spot picking has begun in earnest.

Last week we noticed a number of very small cracks in the shoulder region of Honeycrisp fruit. While these would not affect direct-market sales, they can reduce the quality of stored fruit by browning and becoming an entry point for postharvest rots. As we evaluated this week’s tree-ripe Honeycrisp apples, we saw a number of small cracks when they were examined in the laboratory (Figure 3). While none were as dramatic as stem-end cracks on Gala apples, they certainly are a concern.

In addition to closely monitoring Honeycrisp fruit quality and maturity this year, we also followed changes in the plant hormone, ethylene. Ethylene synthesis drives many of the changes that occur during the maturation and ripening processes. One of the most sensitive responses to ethylene is the loss of starch, which is the reason starch-pattern data are included in these reports. Ethylene synthesis begins at the core region of the fruit which then triggers starch degradation in the apple flesh.

We noted a dramatic upsurge in ethylene evolution from our Honeycrisp samples in mid-August. That paralleled the dramatic decrease in starch and firmness, and the increase in red color that occurred between August 13 and August 19 (See data table).

Daybreak Fuji

Last year, we noted that Daybreak Fuji ripened well ahead of its normal time in September. We are seeing the same pattern in Daybreak Fuji this year. In last week’s sample, we noted that this variety was already maturing and had some varietal flavor. That increase in quality and flavor has continued.

Daybreak Fuji in our samples had softened to 16.8 pounds, lost considerable starch, and measured 16.1° Brix. The grower at the test site we sampled had begun spot picking Daybreak Fuji, which slightly reduced the size and quality of our samples. Other growers in the Mason-Dixon have also noticed this earliness; some have already completed harvesting this variety.

Our weekly results are from commercial orchards located in Adams County, Pennsylvania and, are a result of regional weather conditions and management practices. Local weather conditions, plant growth regulator usage, and tree management system has a great impact on apple maturity. Be sure to monitor your crop closely to see how fruit in your orchard compares with those we tested in Adams County, PA.

Apple Maturity Assessments: Week 6

With their high red color factor, some growers in northern Virginia, central Maryland and southeastern Pennsylvania began spot picking CrimsonCrisp apples this week.

UPDATED: SEPTEMBER 6, 2019

2019 Apple Maturity Assessments: Week Six

Photo: Kathy Hunt, University of Maryland

While CrimsonCrisp apples are not quite tree-ripe, they have adequate size, have lost much of their flesh starch, and are developing varietal flavor.

In addition to picking CrimsonCrisp, growers are also continuing to harvest Daybreak Fuji. The red color in Daybreak is still pale, but many fruit in our sample from Keedysville, Maryland were tree-ripe. They had high soluble solids, good flavor, whitish ground color and small stem-end cracks similar to those seen in tree-ripe Gala apples.

As this was a short week due to the Labor Day holiday, this week’s report summarizes our August harvests and looks ahead to those in September. Honeycrisp and Gala harvests are nearly complete along the Mason-Dixon line, so it’s a good time to summarize this season’s results.

The classic 2014 article by John Delong and Robert Prange, et al. of Nova Scotia reported that the Delta A meter could be used to predict the optimum harvest date for storing Honeycrisp apples. This meter measures ground color by non-destructively estimating chlorophyll in the peel. They reported that Delta A values (or IAD values) between 0.59 to 0.36 were optimum for long-term storage of apples in that Province. That corresponded to picking for storage in late September and early October.

Harvesting greener fruit led to bitter pit problems in stored Honeycrisp. Storing riper fruit than that led to a host of problems after storage. These included “chilling injury” and “soggy breakdown.”

Their work poses a couple of interesting questions in postharvest physiology. First, why would a Minnesota-bred variety be susceptible to chilling injury? Secondly, larger fruit are usually more susceptible to bitter pit. It is curious that during the last few weeks of maturation when Honeycrisp apples are growing so rapidly, they become less susceptible to bitter pit. Why is bitter pit decreasing as Honeycrisp fruit gets larger?

In our Premier Honeycrisp and Honeycrisp storage research using fruit from commercial orchards in Adams County, we were unable to detect any of the classic chilling injury symptoms, nor have we seen any bitter pit develop. Instead, the preconditioning and storage protocols we tested increased fruit rots. At this point, we hypothesize that the warmer, wetter than average summer temperatures during the past few years combined with the additional heat during preconditioning increased storage rots. Warmer temperatures and tree-ripening led to small cracks on the fruit. These were colonized by fruit-rotting fungi during storage.

Pennsylvania is a very large state with great geographic diversity, leading to wide differences in summer temperatures and rainfall. While we did not see a positive response to preconditioning with fruit grown in Adams County, fruit grown in cooler areas affected by the Great Lakes could respond differently. Growers who pick less-mature fruit than what we did, and plan for long-term storage should continue to follow preconditioning protocols used in Michigan, New York, Ontario, and Nova Scotia.

We hypothesize that the warm weather during maturation delayed red color development, but coordinated ripening. This may substitute for the ripening that occurs in the preconditioning process used in cooler growing regions. To test this, we followed the ethylene evolution of Honeycrisp fruit from our test orchard in Adams County. The following graph (Figure 1) shows the changes in starch pattern index and ethylene evolution during our five spot pickings.

Figure 1. Changes in Starch Pattern Index and Ethylene Evolution by Honeycrisp apples spot-picked in Adams County, Pennsylvania during maturation. Photo: Audra Bissett, University of Maryland

With their high red color factor, some growers in northern Virginia, central Maryland and southeastern Pennsylvania began spot picking CrimsonCrisp apples this week. While CrimsonCrisp apples are not quite tree-ripe, they have adequate size, have lost much of their flesh starch, and are developing varietal flavor. (Figure 2)

Figure 2. The typical color of CrimsonCrisp apples spot-picked on September 5, 2019, in Keedysville, Maryland. The fruit was grown on tall spindle planting budded onto G11 root stock. Photo: Kathy Hunt, University of Maryland

Apple Maturity Assessments: Weeks 7 & 8

As the weather cooled a bit and the rains slowed, we noted a dramatic improvement in fruit sweetness.

UPDATED: SEPTEMBER 19, 2019

2019 Apple Maturity Assessments: Weeks Seven and Eight

Photo 1. A small hand-held field refractometer and a larger laboratory refractometer. Photo: Kathy Hunt, University of Maryland

Photo 1 shows two refractometers; a small hand-held field refractometer and a larger laboratory refractometer. In this photo, water core was seen in the center of the fruit and also in the tissue surrounding the vascular bundles of a CrimsonCrisp apple. This glassy tissue develops when the sugar-alcohol sorbitol moves from the leaves to the fruit but is not taken into the cells in the fruit’s flesh. CrimsonCrisp apples with water core have usually lost most of their starch. As this sorbitol collects in the extra-cellular spaces, the fruit becomes sweeter and feels heavier. About 20 percent of the CrimsonCrisp fruit in our samples had water core when they were cut this week.

After Honeycrisp harvest ended, we began following the maturity of two, relatively new early-September apple varieties at the University of Maryland’s farm at Keedysville: Daybreak Fuji and CrimsonCrisp. That farm is located at about 540 feet elevation in the southern part of Washington County, MD. In 2018 Daybreak Fuji appeared to be much more responsive to excessive summer heat than the other varieties we sampled. This again appears to be the case in 2019. Daybreak Fuji responded to this summer’s high temperature by ripening early, but then they continued to hang and color into early September. Some of the early Daybreak Fruit we spot picked had sunburned areas on the peel. The fruit we harvested later from within the canopy had less sunburn.

By the middle of September, CrimsonCrisp apples still measured 22 pounds with 15.5° Brix. The fruit continued to maintain firmness and quality with little preharvest drop during the three weeks they were sampled. Some CrimsonCrisp apples developed 100 percent red color; at that point, they had lost all their starch.

The following table shows data from Daybreak Fuji and CrimsonCrisp apple sampled in 2019. Note the similarity of size, color, firmness, and soluble solids among the three CrimsonCrisp pickings.

Cultivar Date Diameter (inches) Red Color (%) Ground Color Visual Ground Color (Delta A) Firmness (pounds) Starch Pattern (1 – 8) Soluble Solids (°Brix)
Daybreak Fuji (Keedysville MD)                
  5-Sep-19 3.17 68.3 LTY 0.53 13.9 6.4 14.8
  9-Sep-19 3.42 60 WY 0.41 12 6.8 14.7
CrimsonCrisp                
  5-Sep-19 3.03 83 WY 0.48 21.7 6.7 15.6
  9-Sep-19 3.08 93 WY 0.6 21.1 6.6 15.8
  17-Sep-19 3.06 90 LY 0.24 22.3 6.7 15.5

G = Green; LTG = Light Green; YG = Yellowish Green; GY = Greenish Yellow; LTY = Light Yellow; WY = Whitish Yellow

Fuji is a particularly unusual variety. Fuji apples are edible before they are tree-ripe, as they do not taste astringent or bitter. This trait is coupled with the sweetness that develops well before harvest. Japanese apple breeders crossed two American apple varieties, Ralls Janet and Delicious to create Fuji. That breeding program combined the sweetness of Delicious—when it truly was ‘delicious’—with the firmness and storageability of Ralls, an antique Virginia winter apple.

Although the Daybreak Fuji fruit matured early again this year, their soluble solids were much greater than other apples we sampled. Soluble solids were almost 3° Brix greater in early-harvested Daybreak Fuji than tree-ripe Honeycrisp and Gala. On August 27, 2019 we reported the following readings: Daybreak Fuji (16.1° Brix), Buckeye Gala (13.3° Brix), and Honeycrisp (13.6° Brix).

During the past few weeks we’ve also been watching supermarkets in the Washington DC area for local fruit. Early season retail prices for Honeycrisp were good—they were almost double that of other varieties. In these same local supermarkets we also noted an additional half-dollar organic premium for Honeycrisp grown in Washington State. Those organic apples were redder and also greasier than the locally-produced Honeycrisp fruit.

We did notice a few stem punctures in a display of locally-grown Honeycrisp (Photo 2). This was quite unexpected as the fruit had short stems which appeared to have been clipped.

Apple Maturity Assessments: Week 9

Fuji is a particularly unusual variety with great consumer acceptance. Fuji apples are edible well before they are tree-ripe.

UPDATED: SEPTEMBER 27, 2019

2019 Apple Maturity Assessments: Week Nine

Photo 1. EverCrisp apple coloring on second leaf tree on Bud 9 rootstock. While they are already developing red color, picking won’t begin until mid-October. Photo: Kathy Hunt, University of Maryland

Unripe Fuji apples have high levels of soluble solids, good texture and do not taste astringent or bitter. This provides growers with some flexibility in harvest. Fuji has also yielded many bud mutations (or sports) and has been incorporated into apple breeding programs. Those qualities have combined to give growers the option to pick Fuji apples from the beginning of September until the end of October.

This year is on track to be the third driest and warmest September on record in Washington, DC. That city has already recorded 60 days of 90°F temperatures—well above the long-term average of 36 days. It is also above the recent average of the last five years, which recorded 52 days above 90°F. According to last night’s forecast, there is still more warm, dry weather to come. That dry heat will continue to retard red color development but accelerate fruit ripening.

In early September we began following apple maturity at the University of Maryland’s farm at Keedysville. That farm is located in the Southern part of Washington County, Maryland at an elevation of 540 feet. This Piedmont location has conditions similar to many orchards in the Mid-Atlantic region. Like many orchards in the region, apples there are showing the effects of a long hot summer.

Brak Fuji

This week we began sampling Brak Fuji in a rootstock trial at Keedysville. We spot-picked fruit from a slender-spindle rootstock planting. Samples were picked from trees on two rootstocks: Bud 9 and Geneva 202. While there was a great difference in tree vigor, there was little difference in fruit size and quality. The spot-picked samples were averaged from both rootstocks. They were 3.15 inches in diameter, 41 percent red color, with yellowish-green ground color. The fruit were still firm at 16.3 lb. with 13.9° Brix and a starch pattern index of 4.5 on the Cornell chart. While these fruit were edible, the lack of red color and soluble solids makes them unsuitable for the wholesale market. Their starch pattern index suggests they are riper on the inside than they appear on the outside.

Fuji selections have a number of qualities in common. First and foremost, they develop acceptable flavor before they are tree-ripe. They are very high in soluble solids and low in tannins, making them acceptable to consumers long before they have the red color required by the wholesale market. Secondly, Fuji apples will hang for a long time and have less preharvest fruit drop. Fuji does not produce the high levels of ethylene that are produced by varieties known for fruit drop. This makes it easy to delay harvest until fruit develops the desired color and flavor.

EverCrisp

EverCrisp is a remarkable apple. (Photo 1). It resulted from a cross of HoneyCrisp and Fuji, made by the Midwestern Apple Improvement Association (MAIA). The fruit combines the crispness of Honeycrisp with the storage ability of Fuji.

Bill Mackintosh, a well-known grower, nurseryman, and consultant in Northern Virginia, recently made the following comments about EverCrisp, “I’m amazed how much sugar the EverCrisp have at this time. I have tasted them, and they are already sweeter than BC2 Fuji, but we won’t pick them until late October.” He concluded by saying, “That’s an amazing variety.”

Daybreak Fuji

While the season for Daybreak has passed, some fruit continue to hang on the trees. Those late-harvested fruit have continued to develop sweetness and red color. While they have softened somewhat, they have maintained a pleasant sweet taste and are firm enough to be acceptable for direct-marketers.

Cultivar Date Diameter (inches) Red Color (%) Ground Color Visual Ground Color (Delta A) Firmness (pounds) Starch Pattern (1 – 8) Soluble Solids (°Brix)
Daybreak Fuji 5-Sep-19 3.17 68.3 LTY 0.53 13.9 6.4 14.8
  9-Sep-19 3.42 60 WY 0.41 12 6.8 14.7
Brak Fuji/Bud 9 24-Sep-19 3.14 36.3 YG 1.33 16 4.6 13.2
Brak Fuji/G202 24-Sep-19 3.19 51.2 YG 1.12 16.7 4.4 14.7

G = Green; LTG = Light Green; YG = Yellowish Green; GY = Greenish Yellow; LTY = Light Yellow; WY = Whitish Yellow

Apple Maturity Assessments: Week 10

August-like temperatures coupled with a lack of rainfall in September have delayed red color development in our Brak Fuji samples, but continue to decrease the firmness and starch content in these apples.

UPDATED: OCTOBER 3, 2019

2019 Apple Maturity Assessments: Week Ten

GoldRush tall-spindle planting with an Autumn Gala pollenizer tree. Photo: Kathy Hunt, University of Maryland

During the past three years of these maturity studies, we noticed that Fuji fruit were the most affected by unseasonable heat during the late summer and fall. Hot, dry weather leads to sunburn and peel browning and also delays red color development in Fuji. While the outside of the Fuji fruit says, “wait,” the condition of the flesh says, “pick now for storage.” Hopefully, this weekend’s change in weather will deepen the red color in these apples and improve wholesale packouts.

Brak Fuji

This was our second week of sampling Brak Fuji in a rootstock trial at Keedysville. We spot-picked fruit from a slender-spindle rootstock planting. Samples were picked from trees budded onto these rootstocks: Malling 9, Bud 9, and Geneva 202. The differences in quality among the rootstocks were less than one might have expected, and the data from these three rootstocks were averaged. Brak Fuji firmness decreased from 16.4 to 15 pounds in the past week, and their starch-pattern-index increased from 4.1 to 5.2. The soluble solids (sugar) were virtually unchanged, measuring 14.0° Brix. These fruit are mature and ready for storage. The external ground color was rated as yellowish-green using color chips, and the red color was rated as 52 percent. While that percentage seems good, the red-colored areas were quite pale. These Fuji samples did not have the deep red that would be expected in early October.

Daybreak Fuji

While the season for Daybreak Fuji has passed, some fruit continue to hang on the trees. Those rare fruit are still developing sweetness and deeper red color. While they have softened, they are not mealy and are still acceptable for direct-marketing. These later harvested fruit were smaller with lower soluble solids and less red color as they were picked from deep inside the canopy.

Cultivar Date Diameter (inches) Red Color (%) Ground Color Visual Ground Color (Delta A) Firmness (pounds) Starch Pattern (1 – 8) Soluble Solids (°Brix)
Brak Fuji 24-Sep-19 3.16 43.8 YG 1.22 16.4 4.5 13.9
  30-Sep-19 3.37 51.7 YG 1.17 15 5.2 14
Granny Smith 30-Sep-19 3.28 5 G 1.83 18.4 3 12.6
Cripps Pink 30-Sep-19 3.14 28.3 LTG 1.24 22.8 1.5 12.8
GoldRush 30-Sep-19 3.27 10 YG 1.58 23.2 1.6 12.8

G = Green; LTG = Light Green; YG = Yellowish Green; GY = Greenish Yellow; LTY = Light Yellow; WY = Whitish Yellow

Granny Smith, Cripps Pink, and GoldRush

This week we began sampling three additional late-season apples: Granny Smith, Cripps Pink, and GoldRush. These fruit were all picked from tall-spindle trees budded onto Bud 9 rootstocks. Apples of all three varieties had good size despite this past month’s dry weather. They also appear to have been less affected by this summer’s heat than the Fuji fruit we sampled. All three are well behind Fuji and were firm and starchy (Figure 1). Surprisingly these late-season apples had almost an identical level of soluble solids, which ranged from 12.6° to 12.8° Brix. Based on our firmness and starch measurements, Granny Smith apples have begun to start maturing while the Cripps and GoldRush apples have not.

These Grannies would be susceptible to superficial scald if they were picked and stored now. Superficial scald susceptibility is always a problem when green fruit are stored. This susceptibility diminishes once orchard temperatures have dipped below 50°F (10°C). This was initially reported in the 1990s by Dr. Bill Bramlage of the University of Massachusetts and then verified in a national storage trial conducted by a group of postharvest researchers. These lower temperatures will, of course, stimulate red color development in Granny Smith apples. While colder orchard temperatures reduce scald susceptibility, red-colored Grannies might be unacceptable to some wholesale markets.

Figure 1. Color and starch staining pattern of Brak Fuji (upper rows) and Granny Smith apples (lower rows). Photo: Audra Bissett, University of Maryland

Apple Maturity Assessments: Week: 11

The past week’s rainfall and cooler weather had a great effect on Cripps Pink apple color. Of the late-season varieties measured in our tests, Cripps seemed to respond best to these cooler conditions.

UPDATED: OCTOBER 11, 2019

2019 Apple Maturity Assessments: Week Eleven

Figure 1. The red color of Cripps Pink apples improved dramatically during the first week of October. Photo: Kathy Hunt, University of Maryland

While the red color percentage has not changed much during the past two weeks in Brak Fuji fruit, red color percentage in Cripps increased from 28 to 38 percent in spot-picked fruit. The Cripps are still weeks away from harvest but are shaping up to be a very attractive crop (Figure 1 and Figure 2).

Figure 2. Spot-picked Cripps Pink apples in the orchard in Week 11. Photo: Kathy Hunt, University of Maryland

While the red color in Cripps Pink improved nicely, these conditions have delayed red color development in Brak Fuji. During the past three years of maturity studies, we noticed that Fuji fruit were the most affected by unseasonable heat. Hot, dry weather also leads to sunburn and peel browning. While the outside of the Brak Fuji fruit we sampled says, “wait,” the condition of the flesh says, “pick now.”

Figure 3. Color and starch staining pattern of Brak Fuji (upper rows) and Granny Smith apples (lower rows) in Week 11. Photo: Audra Bissett, University of Maryland

Brak Fuji

This was our third week of sampling Brak Fuji in a rootstock trial at Keedysville. We spot-picked fruit from three different rootstocks in a slender-spindle planting. The differences in quality between rootstocks was small. Brak Fuji firmness decreased from 15.0 to 13.7 pounds in the past week, and their starch-pattern-index increased from 5.2 to 5.9. The soluble solids (sugar) increased from 14.0° to 15.2° Brix. These fruit are not dropping, but they are losing storageablility. The external ground color was greenish-yellow using color chips, and the red color was 47 percent. While that percentage seems good, the red-colored areas were still pale and were not the deep red expected in early October.

Cultivar Date Diameter (inches) Red Color (%) Ground Color Visual Ground Color (Delta A) Firmness (pounds) Starch Pattern (1 – 8) Soluble Solids (°Brix)
Brak Fuji 24-Sep-19 3.16 43.8 YG 1.22 16.4 4.5 13.9
  30-Sep-19 3.37 51.7 YG 1.17 15 5.2 14
  8-Oct-19 3.45 46.7 GY 0.8 13.7 5.9 15.2
Granny Smith 30-Sep-19 3.28 5 G 1.83 18.4 3 12.6
  8-Oct-19 3.31 10 WG 1.75 17.9 3.2 12.9
Cripps Pink 30-Sep-19 3.14 28.3 LTG 1.24 22.8 1.5 12.8
  8-Oct-19 3.15 38.3 YG 1.08 20.1 2.1 12.4
GoldRush 30-Sep-19 3.27 10 YG 1.58 23.2 1.6 12.8
  8-Oct-19 3.18 15 YG 1.53 20.1 3.2 12.2

G = Green; WG = Whitish Green; LTG = Light Green; YG = Yellowish Green; GY = Greenish Yellow; LTY = Light Yellow; WY = Whitish Yellow

Granny Smith, Cripps Pink, GoldRush, and Evercrisp

This is our second week of sampling Granny Smith. Fruit were spot-picked from tall-spindle trees at Keedysville, MD. While there was not much change in any external or internal maturity indices between the end of September and early October, many of the Granny Smith apples had water core. We also noted more BMSB feeding scars in the Grannies than in the other varieties sampled this week.

Cripps Pink and GoldRush had almost identical levels of starch and soluble solids. The starch pattern index of these was 2.1 (Cripps Pink) and 3.2 (GoldRush). The soluble solids measured in both were similar - approximately 12° Brix. We did not observe any water core in Cripps or GoldRush apples.

This week we added Evercrisp apples to our trials. While the fruit were still quite firm and harvest has not begun, we were surprised by their sweetness. They had already lost considerable starch with a starch-pattern index of 5.0. Many fruit also had visible water core, with soluble solids measuring 17.3° Brix.

Apple Maturity Assessments: Week 12

Cool-weather and early October rainfall enhanced red color development in Brak Fuji. While the percentage of red color only increased slightly to 52 percent, the loss of ground color and increase of anthocyanin left the fruit with deeper red than in past weeks.

UPDATED: OCTOBER 18, 2019

2019 Apple Maturity Assessments: Week Twelve

Figure 1. The red color intensity in Brak Fuji apples improved during the second week of October. Photo: Kathy Hunt, University of Maryland

Last week, Cripps Pink fruit began turning pink. This week Cripps fruit in full sun increased in the anthocyanin and appeared red, no longer pink. While the Cripps are still a few weeks away from harvest, their size and color makes them look promising.

In addition to improving red color in the peel, we also noticed a continued increase in soluble solids in Brak Fuji. This increase in soluble solids was enhanced by the continued degradation of starch into glucose coupled with the buildup of sorbitol, sugar alcohol. Water core was present in about 80 percent of the fruit in our samples. The watery tissue surrounded the vascular bundles and was also found in small patches of flesh.

Brak Fuji, Daybreak Fuji and Evercrisp

This was our third week of sampling Brak Fuji from a rootstock trial at Keedysville. Brak Fuji fruit firmness decreased slightly from 13.7 to 13.3 pounds in the past week and appears to have reached a plateau. These fruit were still crisp and juicy but have a shortened storage life. Decreasing starch coupled with water core development increased soluble solids (sweetness) from 15.2° to 15.7° Brix. External ground color was a light yellow using color chips, and the red color was 52 percent.

As we have been picking Brak Fuji, we have also been watching a few nearby Daybreak Fuji trees. Their continued attachment and tree-ripening has been surprising. Those fruit that were not picked three weeks ago have remained attached. While the fruit have continued to soften and are now over-mature, they still looked good and had acceptable eating quality. The strong parent-plant inhibition of ripening in Fuji certainly offers the opportunity to harvest fruit over a longer period than apple varieties that tree-ripen quickly and are prone to pre-harvest drop.

Last week we added Evercrisp to this maturity trial. While the fruit were still quite firm and commercial harvest had not yet begun, we were surprised by their sweetness. They had already lost considerable starch with a starch-pattern index of 5.0. Many fruit also had visible water core, with soluble solids measuring 17.3° Brix. Despite not having adequate red color, the Evercrisp apples had the highest level of soluble solids of any variety we have tested this season. The high level of soluble solids and firmness made them feel very dense. While Evercrisp apples will float, they are denser than the other apple varieties we evaluated.

Cultivar Date Diameter (inches) Red Color (%) Ground Color Visual Ground Color (Delta A) Firmness (pounds) Starch Pattern (1 – 8) Soluble Solids (°Brix)
Brak Fuji 24-Sep-19 3.16 43.8 YG 1.22 16.4 4.5 13.9
  30-Sep-19 3.37 51.7 YG 1.17 15 5.2 14
  8-Oct-19 3.45 46.7 GY 0.8 13.7 5.9 15.2
  14-Oct-19 3.29 51.7 LY 0.73 13.3 6.2 15.7
Evercrisp 9-Oct-19 3.47 71.3 GY 0.92 19.3 4.9 17.3
Granny Smith 30-Sep-19 3.28 5 G 1.83 18.4 3 12.6
  8-Oct-19 3.31 10 WG 1.75 17.9 3.2 12.9
  14-Oct-19 3.28 8.3 LG 1.73 16.1 3.6 13.5
Cripps Pink 30-Sep-19 3.14 28.3 LTG 1.24 22.8 1.5 12.8
  8-Oct-19 3.15 38.3 YG 1.08 20.1 2.1 12.4
  14-Oct-19 3.17 45 YG 0.98 19 3.1 12.9
GoldRush 30-Sep-19 3.27 10 YG 1.58 23.2 1.6 12.8
  8-Oct-19 3.18 15 YG 1.53 20.1 3.2 12.2
  14-Oct-19 3.24 10 YG 1.34 21.2 4 14

G = Green; WG = Whitish Green; LTG = Light Green; YG = Yellowish Green; GY = Greenish Yellow; LTY = Light Yellow; WY = Whitish Yellow

Granny Smith, Cripps Pink, and GoldRush

This is our third week of sampling Granny Smith, Cripps Pink and GoldRush. There was not much change in any external or internal maturity indices between the end of September and early October in these late-season varieties. Like Fuji, many of the Granny Smith apples had water core and more BMSB feeding scars than the other varieties at the same location.

Cripps Pink and GoldRush had almost identical levels of starch and soluble solids. The starch pattern index of these was 3.1 (Cripps Pink) and 4.0 (GoldRush). The soluble solids measured reflected the starch measurements, with 12.9° Brix (Cripps Pink) and 14.0° Brix (GoldRush). We did not observe any water core in the Cripps or GoldRush fruit.

As in past years, there was a poor relationship between ground color and starch-staining pattern in GoldRush, making it difficult to spot pick the ripest fruit. We also noted considerable sunburn on these apples as the canopy provided little shade for the fruit on these tall-spindle tree.

Apple Maturity Assessments: Week:13

Cool-weather and early October rainfall enhanced red color development in Brak Fuji and Cripps Pink. While the percentage of red color only increased slightly in Fuji, Cripps increased by almost 25 percent in one week.

UPDATED: OCTOBER 25, 2019

2019 Apple Maturity Assessments: Week Thirteen

Figure 1. The red color of Cripps Pink apples improved dramatically during the third week of October. Photo: Kathy Hunt, University of Maryland

A loss of ground color and an increase of anthocyanin left Cripps with a very attractive red color. While the Cripps are still one or two weeks away from harvest, their size and color make that crop look very promising.

Although the red color in the peel has improved, there has been little change in soluble solids in Brak Fuji during the past two weeks. Water core was also present in many of the sampled fruit. The watery tissue surrounded the vascular bundles and was also found in small patches of flesh.

Brak Fuji and Evercrisp

This was our fifth week of sampling Brak Fuji from a rootstock trial at Keedysville, Maryland. Brak Fuji fruit firmness has remained at about 13 pounds during the past three weeks. These fruit are still crisp and juicy but now have a shortened storage life. Decreasing starch coupled with water core development increased soluble solids (sweetness) to about 15° Brix. This week, the external ground color was a light yellow using color chips, and the red color has increased to 72 percent.

Despite softening and losing starch, the continued attachment and tree-ripening of Brak Fuji fruit is surprising. Fruit that were not picked three weeks ago have remained attached. The strong parent-plant inhibition of ripening in Fuji certainly offers the opportunity for growers to harvest fruit over a longer period than apple varieties prone to pre-harvest drop.

This month we also included Evercrisp in this maturity trial. While the fruit are still quite firm, red color and commercial harvest has begun. While Evercrisp apples have lost considerable starch in October, they have maintained their firmness at 19 pounds. Many fruit had visible water core, and their soluble solids measured 17° Brix. Evercrisp apples have the highest level of soluble solids of any variety we have tested this season. That high level of soluble solids and firmness made Evercrisp feel very dense. While they will float, Evercrisp are denser than any apple variety we have evaluated.

Cultivar Date Diameter (inches) Red Color (%) Ground Color Visual Ground Color (Delta A) Firmness (pounds) Starch Pattern (1 – 8) Soluble Solids (°Brix)
Brak Fuji 24-Sep-19 3.16 43.8 YG 1.22 16.4 4.5 13.9
  30-Sep-19 3.37 51.7 YG 1.17 15 5.2 14
  8-Oct-19 3.45 46.7 GY 0.8 13.7 5.9 15.2
  14-Oct-19 3.29 51.7 LY 0.73 13.3 6.2 15.7
  21-Oct-19 3.41 71.7 LY 0.69 13.6 6.5 15.8
Evercrisp 9-Oct-19 3.47 71.3 GY 0.92 19.3 4.9 17.3
  16-Oct-19 3.41 58.8 GY 0.83 20.3 5.3 17.5
  23-Oct-19 3.47 69.3 GY 0.81 19.1 5.8 17.6
Granny Smith 30-Sep-19 3.28 5 G 1.83 18.4 3 12.6
  8-Oct-19 3.31 10 WG 1.75 17.9 3.2 12.9
  14-Oct-19 3.28 8.3 LG 1.73 16.1 3.6 13.5
  21-Oct-19 3.42 10 WG 1.67 16.7 3.6 14.5
Cripps Pink 30-Sep-19 3.14 28.3 LTG 1.24 22.8 1.5 12.8
  8-Oct-19 3.15 38.3 YG 1.08 20.1 2.1 12.4
  14-Oct-19 3.17 45 YG 0.98 19 3.1 12.9
  21-Oct-19 3.21 68.3 YG 0.78 18.7 3.9 14
GoldRush 30-Sep-19 3.27 10 YG 1.58 23.2 1.6 12.8
  8-Oct-19 3.18 15 YG 1.53 20.1 3.2 12.2
  14-Oct-19 3.24 10 YG 1.34 21.2 4 14
  21-Oct-19 3.4 15 YG 1.25 21.8 4.1 14.6

G = Green; WG = Whitish Green; LTG = Light Green; YG = Yellowish Green; GY = Greenish Yellow; LTY = Light Yellow; WY = Whitish Yellow

Granny Smith, Cripps Pink, and GoldRush

This is our fourth week of sampling Granny Smith, Cripps Pink, and GoldRush. There was a slow, steady increase in soluble solids and a slight decrease in firmness in all these varieties. Like Fuji, many of the Granny Smith apples had water core.

Cripps Pink and GoldRush had almost identical levels of starch and soluble solids. The starch pattern index of these was 3.9 (Cripps Pink) and 4.1 (GoldRush). The soluble solids measured reflected the starch measurements, with 14.0° Brix (Cripps Pink) and 14.6° Brix (GoldRush). Although they are beginning to ripen, we did not observe any water core in the Cripps or GoldRush.

As in past years, there was a poor relationship between ground color and starch-staining pattern in GoldRush. This makes it difficult to spot pick the ripest GoldRush. We also noted rain cracking and sunburn on these apples. Since it is difficult to gauge the flesh maturity by looking at the ground color, it is easy to understand the reason that some fruit crack severely while others of similar-size and ground color do not crack.

Apple Maturity Assessments: Week 14, Final Picking

Cool-weather and early October rainfall enhanced red color development and fruit ripening in Cripps Pink. In the past few weeks, Cripps’ loss of ground color and increase of anthocyanin gave these fruit a very attractive, deep red color.

UPDATED: OCTOBER 31, 2019

2019 Apple Maturity Assessments: Week Fourteen, Final Picking

Figure 1. Red color of Cripps Pink apples improved dramatically during the third week of October. Photo: Kathy Hunt, University of Maryland

The Cripps Pink apples in our maturity sampling now have good size, color, and flavor for storage and for direct marketing. As the red color in the peel has improved during October (Figure 1), the soluble solids in Cripps’ fruit have also increased from 12° Brix to almost 15° Brix. With cold weather predicted during the next few weeks, it would be good to complete the apple harvest by Election Day.

Granny Smith, Cripps Pink, and GoldRush

This is our fifth-week sampling Granny Smith, Cripps Pink, and GoldRush. There has been a slow, steady increase in soluble solids and a slight decrease in firmness in these three varieties. Twenty percent of the Granny Smith apples had water core. Despite this, they had the lowest level of soluble solids.

Cripps Pink and GoldRush had almost identical levels of carbohydrates. The starch pattern indices were 5.0 (Cripps Pink) and 4.2 (GoldRush) (Figures 2 and 3). Their soluble solids also continued to increase with 14.8° Brix (Cripps Pink) and 16.8° Brix (GoldRush). Although these varieties have begun to ripen, we did not observe any water core in them.

As in past years, there was a poor relationship between ground color and starch-staining pattern in GoldRush. This makes it difficult to spot-pick the ripest GoldRush apples. We also noted considerable rain cracking and sunburn on these fruit. Since it is difficult to gauge the flesh maturity by looking at the ground color, it is easy to understand the reason some fruit crack severely while others of similar size and ground color are not cracked.

While the Granny Smith apples were more mature than Cripps and GoldRush at the beginning of October, these two varieties were riper by the end of the month. Sub-freezing weather is predicted soon. Growers should complete Cripps Pink and GoldRush harvest this week to avoid losses like those that occurred in November 2017, when these two late-harvested varieties froze solid on the trees.

Brak Fuji and Evercrisp

We did not sample Brak Fuji or Evercrisp apples this week as the harvest was completed at our test sites; however, it is worth looking back on Fuji maturation and tree-ripening. Despite softening and losing starch, the continued attachment of Brak Fuji fruit during October was surprising. Fruit that were not picked at the beginning of the month remained attached for weeks. The strong parent-plant inhibition of ripening in Fuji certainly offered the opportunity for growers to harvest fruit over a longer period than apple varieties prone to pre-harvest drop.

We also included Evercrisp in this year’s maturity trials. While Evercrisp apples lost considerable starch in October, they have maintained their firmness at 19 pounds. Like Fuji, many Evercrisp fruit had visible water core, and their soluble solids measured 17° Brix. Evercrisp apples had the highest level of soluble solids of any variety we tested this year. They were considerably higher than Fuji and Cripps, which have had the greatest levels of soluble solids during the past three years of maturity testing. High soluble solids and firmness made Evercrisp feel very dense. While these apples will float, Evercrisp are the densest apple variety we evaluated.

 

Cultivar Date Diameter (inches) Red Color (%) Ground Color Visual Ground Color (Delta A) Firmness (pounds) Starch Pattern (1 – 8) Soluble Solids (°Brix)
Brak Fuji 24-Sep-19 3.16 43.8 YG 1.22 16.4 4.5 13.9
  30-Sep-19 3.37 51.7 YG 1.17 15 5.2 14
  8-Oct-19 3.45 46.7 GY 0.8 13.7 5.9 15.2
  14-Oct-19 3.29 51.7 LY 0.73 13.3 6.2 15.7
  21-Oct-19 3.41 71.7 LY 0.69 13.6 6.5 15.8
  28-Oct-19 Harvest Complete            
Evercrisp 9-Oct-19 3.47 71.3 GY 0.92 19.3 4.9 17.3
  16-Oct-19 3.41 58.8 GY 0.83 20.3 5.3 17.5
  23-Oct-19 3.47 69.3 GY 0.81 19.1 5.8 17.6
  28-Oct-19 Harvest Complete            
Granny Smith 30-Sep-19 3.28 5 G 1.83 18.4 3 12.6
  8-Oct-19 3.31 10 WG 1.75 17.9 3.2 12.9
  14-Oct-19 3.28 8.3 LTG 1.73 16.1 3.6 13.5
  21-Oct-19 3.42 10 WG 1.67 16.7 3.6 14.5
  28-Oct-19 3.42 6.3 LTG 1.63 17 3.8 13
Cripps Pink 30-Sep-19 3.14 28.3 LTG 1.24 22.8 1.5 12.8
  8-Oct-19 3.15 38.3 YG 1.08 20.1 2.1 12.4
  14-Oct-19 3.17 45 YG 0.98 19 3.1 12.9
  21-Oct-19 3.21 68.3 YG 0.78 18.7 3.9 14
  28-Oct-19 3.21 53.3 GY 0.61 18.7 5 14.9
GoldRush 30-Sep-19 3.27 10 YG 1.58 23.2 1.6 12.8
  8-Oct-19 3.18 15 YG 1.53 20.1 3.2 12.2
  14-Oct-19 3.24 10 YG 1.34 21.2 4 14
  21-Oct-19 3.4 15 YG 1.25 21.8 4.1 14.6
  28-Oct-19 3.25 4.3 YG 1 20.7 4.2 16.8

G = Green; WG = Whitish Green; LTG = Light Green; YG = Yellowish Green; GY = Greenish Yellow; LTY = Light Yellow; WY = Whitish Yellow