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WA 38 Defects Guide

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WA 38 Common Defects and Unique Characteristics Near Harvest and During Storage

Written by Ines Hanrahan, Executive Director, WA Tree Fruit Research Commission; Carolina A. Torres, Associate Prof., Endowed Chair in Tree Fruit Postharvest Systems, Washington State University Sept 2020

Collaborators
WSU: Stefano Musacchi, Sara Serra, Kate Evans, Karen Lewis
USDA-ARS: David Rudell
WTFRC: Manoella Mendoza, Mackenzie Perrault
PVM: Jill Burberry

This guide was developed with a focus on defects typically observed in WA 38 to date. It does not consider some commonly occurring defects of all apples such as bruising or decay. Defects only observed under special laboratory conditions known to exacerbate symptoms have been omitted also.


Table of Contents


Defects visible during the growing season, at harvest, or after storage for WA 38


Stem Puncture

First detection1 Growing season / Harvest / After Storage
Incidence rate2 Common / Uncommon
Description Skin laceration caused by a fruit’s stem or the stem of another fruit.
Located anywhere on the apple.
Puncture can be fresh (without healed tissue), healed, desiccated, or necrotic.
Secondary infections can occur.
Possible confusion Clipper damage, bird peck, skin cracking, or spur puncture.
Known management strategies Stem clipping at harvest. For more information see: http://treefruit.wsu.edu/wa-38-stem-punctures-packout/
1First detection: Bold font indicates which stage the defect should first be detected.
2Incidence rate: common = defect expected to be observed in the orchard; uncommon = defect rarely observed. Bold font indicates incidence type.

Stem Puncture Gallery

Click image to enlarge

apple with half-moon shaped cut penetrating the skin with some juice released.
Fresh stem puncture.
apple showing half-moon shaped cut into skin with scarring.
Older stem puncture with healed tissue present.

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Clipper Damage

First detection1 Growing season / Harvest / After Storage
Incidence rate2 Common / Uncommon
Description A small wound (less than 5mm/0.2 inches in diameter) in the stem bowl area of fruit.
May have secondary fungal infection.
Possible confusion Splits, stem puncture, bird peck.
Known management strategies Crew training and in-field Quality Control (QC).
1First detection: Bold font indicates which stage the defect should first be detected.
2Incidence rate: common = defect expected to be observed in the orchard; uncommon = defect rarely observed. Bold font indicates incidence type.

Clipper Damage Gallery

Click image to enlarge

looking at stem bowl with rounded wound next to the stem.

Looking down at the stem bowl, there are two gouge marks visible caused by stem clipping.

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Limb Rub

First detection1 Growing season / Harvest / After Storage
Incidence rate2 Common / Uncommon
Description Physical damage of various size on the skin of fruit, most often leading to suberized tissue.
If sustained early during fruit development suberization will develop in conjunction with depressed fruit growth in the affected area or appear as indentations.
Severe cases of limb rub can cover 25% of the fruit surface and tissue may crack and/or become infected with fungi.
Light damage may appear as suberized scratches (tractor blight).
Possible confusion Russet, sunburn cracking, stem puncture, powdery mildew
Known management strategies Adjust tree training to avoid limbs that dangle excessively.
1First detection: Bold font indicates which stage the defect should first be detected.
2Incidence rate: common = defect expected to be observed in the orchard; uncommon = defect rarely observed. Bold font indicates incidence type.

Limb Rub Gallery

click image to enlarge

Apple on tree with limb rub scarring from the limb laying across the fruit.
Scarring caused by the fruit rubbing against the twig during wind events.
apple showing a small narrow injury on the side from a limb.
Indentation caused by a twig digging into the side of the fruit.
Severe scarring and indentation caused by the fruit being pressed against a branch for a prolonged period; resembles early-season caterpillar feeding.

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Green Spot

First detection1 Growing season / Harvest / After Storage
Incidence rate2 Common / Uncommon
Description Superficial, pencil eraser to dime size, green to brown lesions that appear within 4-6 weeks of harvest of unknown cause.
Discolorations may fade with maturity and red color development. Generally located near the shoulder of the fruit.
Possible confusion Bitter pit, stink bug
Known management strategies None known. For more information see: http://treefruit.wsu.edu/article/preliminary-observations-on-green-spot-symptoms-in-wa-38/
1First detection: Bold font indicates which stage the defect should first be detected.
2Incidence rate: common = defect expected to be observed in the orchard; uncommon = defect rarely observed. Bold font indicates incidence type.

Green Spot Gallery

Click image to enlarge

Apple on tree showing multiple green patches.

Moderate green spot at harvest.

WA 38 fruit showing scattered green spot blemishes o the surface.

WA 38 fruit with several surface blemishes on the shoulders along with splits.

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Insect Damage

First detection1 Growing season / Harvest / After Storage
Incidence rate2 Common / Uncommon
Description Damage/deformation caused by insects feeding on developing fruit at various stages of development.
May lead to secondary infections.
Possible confusion variable
Known management strategies Pest management recommendations available at http://cpg.treefruit.wsu.edu and decisionaid.systems
1First detection: Bold font indicates which stage the defect should first be detected.
2Incidence rate: common = defect expected to be observed in the orchard; uncommon = defect rarely observed. Bold font indicates incidence type.

Insect Damage Gallery

Click image to enlarge

A smaller ‘wormhole’ likely caused by a codling moth entering the fruit to feed earlier in the season.
An example of a ‘wormhole’ likely caused by codling moth feeding later in the season.
Both fruit show mild leafroller feeding damage with surface scaring. More severe damage can lead to infection.
Classic thrips feeding damage is called Pansyspot because of the flower-like appearance of discolored tissue surrounding a small scarred feeding hole.
This deep depression may be the result of early season Lygus bug feeding.

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Sunburn

First detection1 Growing season / Harvest / After Storage
Incidence rate2 Common / Uncommon
Description Skin discoloration, photobleaching, and necrosis on the sun-exposed side of the fruit due to high light and high heat on its surface.
Possible confusion none known
Known management strategies Summary article for horticultural management:  http://treefruit.wsu.edu/article/apple-sunburn-101/
Sprayable recommendations available online at http://cpg.treefruit.wsu.edu
1First detection: Bold font indicates which stage the defect should first be detected.
2Incidence rate: common = defect expected to be observed in the orchard; uncommon = defect rarely observed. Bold font indicates incidence type.

Sunburn Gallery

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Apple on tree residing amongst leaves where one side is exposed to the sun and showing browin area surrounded by white photo-bleached ring.

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Sun Stress Water Soaking

First detection1 Growing season / Harvest / After Storage
Incidence rate2 Common / Uncommon
Description Localized sun-induced watercore/water soaking of the flesh on the sun-exposed side of the apple.
If cold, stored fruit may develop internal browning.
Possible confusion none known
Known management strategies N/A
1First detection: Bold font indicates which stage the defect should first be detected.
2Incidence rate: common = defect expected to be observed in the orchard; uncommon = defect rarely observed. Bold font indicates incidence type.

Sun Stress Water Soaking Gallery

Click image to enlarge

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Splits & Cracks

First detection1 Growing season / Harvest / After Storage
Incidence rate2 Common / Uncommon
Description Cracking or splitting of the fruit skin can occur in the stem bowl as vertical or horizontal cracks, on the shoulder, cheek, and the calyx end of the fruit.
Cracks may be present at harvest or develop in storage or during and after packing of fruit.
Secondary infection with fungi is common, as is feeding of earwigs in stem bowl cracks.
Single stem bowl cracks at harvest are the most common type of splitting observed in WA 38.
Possible confusion Rain-induced cracking, over-mature fruit splitting
Known management strategies More stem bowl cracks develop as fruit matures.
To date, it is recommended to harvest fruit before a starch clearing of 3.5 is reached.
1First detection: Bold font indicates which stage the defect should first be detected.
2Incidence rate: common = defect expected to be observed in the orchard; uncommon = defect rarely observed. Bold font indicates incidence type.

Splits & Cracks Gallery

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Single stem bowl crack.
Triple stem bowl crack.
Looking down into the stem bowl showing two cracks radiating away from the stem.
Double stem bowl crack.
Calyx end cracking. The larger crack was worsened by earwig or bird feeding.
Multiple cracks radiating from the center of the calyx.
Examples of varying degrees of calyx end cracking.
apple stem bowl with a circular crack radiating more than half way around the bowl.
Radial stem bowl crack.
Lenticel cracking.
Side cracking on fruit just prior to harvest.

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Russet (Powdery Mildew)

First detection1 Growing season / Harvest / After Storage
Incidence rate2 Common / Uncommon
Description Smooth russet on the cheek of the fruit that may cover the entire fruit surface in a net-like, tan-colored pattern commonly caused by powdery mildew.
Honeycrisp is also susceptible to this type of russet.
Possible confusion Limb rub
Known management strategies Powdery mildew management recommendations are available online at http://cpg.treefruit.wsu.edu.
1First detection: Bold font indicates which stage the defect should first be detected.
2Incidence rate: common = defect expected to be observed in the orchard; uncommon = defect rarely observed. Bold font indicates incidence type.

Russet Gallery

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apple showing a lateral band of superficial scarring resulting from apple mildew.
Lattice-like surface scarring caused by mildew.

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Blotch Pit

First detection1 Growing season / Harvest / After Storage
Incidence rate2 Common / Uncommon
Description Blotch pit is characterized by larger (>dime size) lesions of irregular shape at any location, but usually starting near the calyx.
The lesions may coalesce and flesh corking may extend to a depth of 1/4th of an inch (6mm).
The disorder shows distinct sunken margins with a rough surface structure of the lesion interior.
Symptoms usually express after storage.
Like bitter pit, flesh browning will likely increase and deepen after harvest.
Forced ripening will induce symptom expression.
For more information see  https://treefruitresearch.org/resources/superficial-skin-disorder-guide/.
Possible confusion Bitter pit, mixed with green spot symptoms
Known management strategies Physiological disorder associated with nutritional imbalance, hot summers, and late harvest.
1First detection: Bold font indicates which stage the defect should first be detected.
2Incidence rate: common = defect expected to be observed in the orchard; uncommon = defect rarely observed. Bold font indicates incidence type.

Blotch Pit Gallery

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Different manifestations of blotch pit.

side of apple showing two areas with brown sunken irregular shaped patches.

Severe blotch pit symptoms.

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Soft Scald

First detection1 Growing season / Harvest / After Storage
Incidence rate2 Common / Uncommon
Description Soft scald is a chilling injury. External damage presents after several weeks of storage anywhere on the fruit but may appear preharvest if low temperatures coincide with more advanced maturity.
Symptoms include sharply defined, irregularly shaped, smooth, ribbon-like, tan to mahogany brown lesions of the skin that are typically soft to the touch.
Small lesions (< 0.5 inch in diameter) can be firm. Early symptoms look like bruising. At later stages, skin lesions are often invaded by secondary pathogens.
The injury initially presents in peel tissue and then advances into the flesh where it forms brown patches and penetrates less than 1 inch deep (i.e. does not reach the core).
Possible confusion Bruising, soggy breakdown (no external symptoms; browning starts 2-3mm under the skin; watery)
Known management strategies None tested for WA 38.
1First detection: Bold font indicates which stage the defect should first be detected.
2Incidence rate: common = defect expected to be observed in the orchard; uncommon = defect rarely observed. Bold font indicates incidence type.

Soft Scald Gallery

Click image to enlarge

postharvest apple showing a brown irregular shaped region with a distinct margin.

postharvest apple showing a brown irregular shaped region with a distinct margin.

Postharvest apple showing a brown irregular shaped region with a distinct margin; a second similar region seen to the left.

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Unique Defect Characteristics found in WA 38



Leaf Shading

First detection1 Growing season / Harvest / After Storage
Incidence rate2 Common / Uncommon
Description Sharp margins in fruit skin coloration where fruit is exposed to sun, but parts of the surface are obscured by a leaf.
Symptoms present as a light green to yellow oval area on the fruit shoulder or cheek where covered by leaf.
Note that leaf shaded area has potential to develop into photo-oxidative sunburn.
Possible confusion photo-oxidative sunburn, herbicide damage
Known management strategies N/A
1First detection: Bold font indicates which stage the defect should first be detected.
2Incidence rate: common = defect expected to be observed in the orchard; uncommon = defect rarely observed. Bold font indicates incidence type.

Leaf Shading Gallery

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Apple on tre showing an un-colored area peaking out from under a leaf.

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Wandering Sepal

First detection1 Growing season / Harvest / After Storage
Incidence rate2 Common / Uncommon
Description flowering part (sepal) growing on the body of the fruit.
May be located anywhere from calyx end to stem bowl.
Possible confusion None known
Known management strategies N/A
1First detection: Bold font indicates which stage the defect should first be detected.
2Incidence rate: common = defect expected to be observed in the orchard; uncommon = defect rarely observed. Bold font indicates incidence type.

Wandering Sepal Gallery

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close-up view of stem end showing an irregular pink pigmented bulge on the edge of the stem bowl surrounded by sunken green pigmented skin tissue.

close-up view showing a rounded raised area next tot he stem bowl with a depressed under pigmented margin.

close up of an irregular area on the fruit shoulder with a slight bulge and a Y-shaped depressed lower margin with under pigmented skin, tail of Y extends down the side of the fruit.

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Fruit Shape Variations

First detection1 Growing season / Harvest / After Storage
Incidence rate2 Common / Uncommon
Description Fruit shape variations that may be observed: uneven, elongated, squatty, columnar, or deformed stems.
Possible causes include viral infection, poor pollination, hormone imbalance, fruit from young orchards, or extra carpel.
Possible confusion None known
Known management strategies N/A
1First detection: Bold font indicates which stage the defect should first be detected.
2Incidence rate: common = defect expected to be observed in the orchard; uncommon = defect rarely observed. Bold font indicates incidence type.

Fruit Shape Variations Gallery

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three size and shape variations: slightly short and squat, more rounded, and slightly elongation top to bottom.

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Hard Green Background

First detection1 Growing season / Harvest / After Storage
Incidence rate2 Common / Uncommon
Description Background color is green as opposed to breaking (yellow green).
Possible confusion None known
Known management strategies Avoid harvesting fruit until the background color has softened to guarantee the development of full flavor after storage.
1First detection: Bold font indicates which stage the defect should first be detected.
2Incidence rate: common = defect expected to be observed in the orchard; uncommon = defect rarely observed. Bold font indicates incidence type.

Hard Green Background Gallery

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Excessively green background color.
Background color is too green.
The background color here is an optimal yellow-green.

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Lack of Red Color

First detection1 Growing season / Harvest / After Storage
Incidence rate2 Common / Uncommon
Description Lack of red skin color due to insufficient light exposure on the tree.
Possible confusion None known
Known management strategies WA 38 develops red color easily when exposed to light.
1First detection: Bold font indicates which stage the defect should first be detected.
2Incidence rate: common = defect expected to be observed in the orchard; uncommon = defect rarely observed. Bold font indicates incidence type.

Lack of Red Color Gallery

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Packing flat of apples showing more of a blush red than full red coloring, considered to be under-colored.


Contact

Carolin Torres formal portraitCarolina Torres
Endowed Chair Postharvest Systems, Horticulture
WSU Tree Fruit Research & Extension Center
Wenatchee, WA
phone: 509-293-8808
email: ctorres@wsu.edu


treefruit.wsu.edu articles may only be republished with prior author permission © Washington State University. Republished articles with permission must include: “Originally published by Washington State Tree Fruit Extension at treefruit.wsu.edu” along with author(s) name, and a link to the original article.


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