Fruit Cracking and Fruit Drop of Greenhouse Tomatoes

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» Fruit cracking and fruit drop usually result from stressful environmental conditions.

» Fruit cracking is more common during the summer months, while fruit drop is more common in fall- and winter-planted crops.

» Adjusting environmental conditions and providing balanced nutrition can help manage fruit cracking and fruit drop.

FRUIT CRACKING

Fruit cracking is a splitting of the fruit’s epidermis (skin) in the area where the fruit attaches to the stem.1 Cracking is usually caused by pressure within the fruit, associated with growth and water levels that stress the skin, causing it to tear.2 Cracking can occur in a pattern radiating from the stem scar toward the blossom end (Figure 1A); this is called radial cracking. Concentric cracking is cracking that occurs in a circular pattern around the stem scar (Figure 1B). Russeting, or cuticle cracking, is another fruit cracking that appears as small hairline cracks or a roughening of the fruit’s skin.1,3 All of these forms of fruit cracking develop on fruit that is nearing maturity, especially on fruit that is starting to change color. The skin becomes less flexible at this developmental stage, leading to higher pressures developing in the fruit and making the skin more likely to tear or split. Cracks initiated earlier often become deeper than cracks initiated on more developed fruit. The altered appearance reduces the marketability of the fruit, and the cracks can be sites of infection by fungi and bacteria, resulting in fruit rot.1,2,3

CAUSES OF CRACKING

Variations in fruit growth rates caused by fluctuating temperatures and hydration can result in cracking. A period of water stress, followed by a rapid influx of water and solutes, increases the incidence and severity of cracking.1,2,3,4 Periods of high temperature (over 86 °F, 30 °C) or when the difference between day- and night-time temperatures is greater than 36 °F (20 °C ) can increase the likelihood of cracks developing, as high temperatures can increase fruit growth rate and skin firmness/ strength. Higher fruit temperatures and humidity levels can also cause higher hydrostatic pressure within the fruit, increasing the level of fruit cracking.1

These conditions can result in the immediate cracking of ripe fruit and delayed cracking of green fruit. Light levels can also affect fruit size, growth rate, skin structure, and fruit temperature, thus impacting cracking levels.5,6 Fruit cracking is more common in July and August when temperatures and light levels are higher than in the fall. However, in unheated greenhouses, large fluctuations in temperature can occur that result in the development of fruit cracks.1 Factors that alter the growth rate and succulence of plants can also impact the level of cracking.

High levels of nitrogen that promote succulent plants and rapidly growing fruit can result in more fruit cracking.3 The susceptibility to fruit cracking varies by cultivar. Genotypic differences in fruit cellular composition and skin structure affect susceptibility to cracking.More susceptible varieties may start to crack at the mature green stage, less susceptible varieties at the breaker (pink) stage, and more tolerant varieties at the redripe stage. Cracks do not usually develop on resistant varieties.3

Figure 1. (A) Radial and (B) concentric fruit cracking symptoms. Figure 1. (A) Radial and (B) concentric fruit cracking symptoms.

Cracking is more common on large-fruited varieties because these fruits tend to have thinner skins with lower tensile strength and extensibility, and they often produce fewer fruit per plant.6 Fewer fruit can result in higher levels of soluble solids entering each fruit, which can lead to cracking. Factors that are associated with increased susceptibility to fruit cracking include:

• Large fruit size

• Low skin tensile strength

• Low skin extensibility at the breaker stage

• Thin skin and pericarp

• Few fruits per plant (low fruit load)

• Fruit not shaded by the foliage

• Higher juice content, acidity, and total sugar content

• Lower insoluble solid content1

A pair of dominant genes that determine resistance to concentric and radial cracking have been identified.1 Determinate varieties tend to be less susceptible to concentric fruit cracking. Indeterminate and semi-indeterminate varieties are more often susceptible, in part because they set fruit over a longer period, and thus tend to have fewer fruit on the plant at any one time.

GREENHOUSE COVERS AND CRACKING

It has been shown that the materials used to cover greenhouses can affect the intensity and quality of light entering the greenhouse. Glass, plastic films, and rigid plastic panels vary in total light transmission, the selective transmission of different wavelengths of light in the photosynthetically active region (PAR) and near-infrared, and the ability to block UV-A and UV-B wavelengths. The materials can also affect the house’s temperature, humidity, and vapor pressure deficit levels.7,8,9 Some studies have shown that these differences can result in changes in the quality of tomato fruit and potentially affect the level of fruit cracking.7,8,10 Materials that result in higher temperatures and higher humidity levels may increase the likelihood of fruit cracking during the summer months. A house’s airtightness or leakiness can also affect the stability of temperature and humidity conditions, with fluctuating temperatures and high humidity conditions more likely to contribute to increased cracking. The use of shade cloth in greenhouses in the summer in Greece was shown to decrease the levels of fruit cracking by up to 50% compared to nonshaded houses.8

MANAGING FRUIT CRACKING

To help manage fruit cracking, consider selecting crack-resistant varieties if they meet the other required criteria for the market.1,6 Manage irrigation schedules to provide even water availability and avoid fluctuations in plant hydration. Consider reducing water applications if fruit cracking is occurring and when harvesting fruit from clusters on the upper part of the vine.1,3,4

Prevent temperatures in the house from getting too high and maintain minimal differences between daytime and nighttime temperatures to reduce diurnal changes in fruit temperatures. Gradually increase the temperature in the house in the pre-dawn and early morning hours.1,6 Manage humidity levels to allow plants to cool through transpiration. Also, apply shade cloths or whitewash to avoid light intensities that are too high. Avoid overpruning foliage and prevent defoliation from disease inorder to limit the exposure of fruit to direct sunlight that can result in fruit temperature fluctuations.1,3 Provide balanced nutrition, avoiding overapplication of nitrogen that can promote overly succulent plant growth and inhibit the uptake of other nutrients. Consider harvesting fruit before they reach the pink stage.1,6

FRUIT DROP

Fruit drop (or fruit fall) is a condition where fruits drop from the vine before they are fully mature. Fruit drop is usually the result of stressful environmental conditions and occurs most commonly on fall and mid-winter planted tomato crops.11,12 A lack of sufficient light in fall- and winter-planted crops makes it difficult for the plants to produce enough food through photosynthesis to supply their needs during fruit production.13

Stress from high temperature, high humidity, and low light levels increases the likelihood of premature fruit drop. When fruit starts to form, nighttime temperatures in the house should be kept fairly low depending on the average amount of light received during the day. In the Ontario area, a recommended range of nighttime temperatures in the late fall and winter is from 63 ° to 65 °F (17.5 ° to 18.5 °C) and daytime temperatures from 64° to 65 °F (18 ° to 18.5 °C). In areas that receive greater amounts of sunlight in the winter, higher nighttime and daytime temperatures may be warranted.13 Removing too much foliage by pruning can also contribute to the development of fruit drop because the plant is unable to produce enough photosynthates.

Insufficient watering, overwatering, and the stress from uneven watering can all lead to increased levels of fruit drop, especially on plants with large fruit or heavy fruit loads. Watering problems reduce the plant’s ability to take up water, oxygen, and nutrients, leading to stress that results in fruit drop.11,12,13 Under and over-fertilization can also contribute to fruit drop.

Phosphorus is used in fruit development, and potassium is needed for general plant growth. If nitrogen levels are too high, the uptake of phosphorus and potassium can be inhibited, affecting fruit development and promoting foliar growth over fruit production. Balanced nutrition and lower nutrient levels during periods of low light can help prevent fruit drop.11,12,13

SOURCES

1Olle, M. and Williams, I. 2017. Physiological disorders in tomato and some methods to avoid them. Journal of Horticultural Science & Biotechnology 92:223-230.

2Sperry, W., Davis, J., and Sanders, D. 1996. Soil moisture and cultivar influence cracking, blossom-end rot, zippers, and yield of staked fresh-market tomatoes. HortTechnology 6:21–24.

3Scott, J. 2014. Growth cracks. 2014. In Jones, J., Zitter, T., Momol, T., and Miller, S., Eds. Compendium of Tomato Diseases and Pests, Second Edition. American Phytopathological Society.

4Peet, M. and Willits, D. 1995. Role of excess water in tomato fruit cracking. HortScience 30:65-68. Retrieved Jan 14, 2025, from https://doi.org/10.21273/HORTSCI.30.1.65.

5Liu, Y., Yang, J., Li, Z., Tchuenbou-Magaia, F., and Liu, Y. 2024. Investigation on the environmental causes of tomato fruit cracking and its propagation prediction in greenhouse. Journal of texture Studies. https://doi.org/10.1111/jtxs.12845..

6Peet, M. 1992. Fruit cracking in tomato. Hort Technology 2:216–223.

7Petropoulos, S., Fernandes, A., Katsoulas, N., Barros, L., and Ferreira, I. 2018. The effect of covering material on the yield, quality and chemical composition of greenhouse-grown tomato fruit. J Sci Food and Agriculture 99: 3057-3068.

8Raquel, S., Igor, D., José, G., and Margarida, O. 2023. Greenhouse tomato technologies and their influence in Mediterranean region. Page Ch. 4 in: Tomato Cultivation and Consumption. L. Francesco, ed. IntechOpen, Rijeka.

9Kwon, J., Khoshimkhujaev, B., Lee, J., Yu, ., Park, K., Choi, H. 2017. Growth and yield of tomato and cucumber plants in polycarbonate or glass greenhouses. Korean Journal of Horticultural Science and Technology 35:79-87. DOI: 10.12972/kjhst.20170009.

10Papaioannou, C., Katsoulas, N., Maletsika, P., Siomos, A., and Kittas, C. 2012. Effects of a UVabsorbing greenhouse covering film on tomato yield and quality. Spanish J. of Ag. Research 10:959-966.

11Beaumont, L. 7 reasons tomatoes falling off before ripe & their remedies. Gardeners Yards. https://gardenersyards.com/why-are-my-tomatoes-falling-off-the-vine/.

12Rodrigues, K. Tomatoes dropping of the plant: 5 critical reasons. Gardening Mentor. https://gardeningmentor.com/why-are-tomatoes-dropping-off-the-plant/.

13Why are my tomatoes falling off the vine? 6 common causes and solutions. BountifulGardener. https://www.bountifulgardener.com/why-are-my-tomatoes-falling-off-the-vine-6-common-causes-and-solutions/.

Websites verified 01/22/2025

ADDITIONAL INFORMATION

For additional agronomic information, please contact your local seed representative. Performance may vary, from location to location and from year to year, as local growing, soil and weather conditions may vary. Growers should evaluate data from multiple locations and years whenever possible and should consider the impacts of these conditions on their growing environment. The recommendations in this article are based upon information obtained from the cited sources and should be used as a quick reference for information about greenhouse cucumber production. The content of this article should not be substituted for the professional opinion of a producer, grower, agronomist, pathologist and similar professional dealing with this specific crop.

BAYER GROUP DOES NOT WARRANT THE ACCURACY OF ANY INFORMATION OR TECHNICAL ADVICE PROVIDED HEREIN AND DISCLAIMS ALL LIABILITY FOR ANY CLAIM INVOLVING SUCH INFORMATION OR ADVICE.

6814_504400 Published 02-12-2025

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