Strawberry plants usually produce fruits that not only offer flavor but are also attractive. However, sometimes they can yield deformed or ugly fruit. Deformed strawberries can be so malformed that they don’t even resemble normal strawberries. In addition to fruit deformities, strawberry plants can have leaf abnormalities. External factors such as weather cause many strawberry plant deformities.
Deformed strawberries are known by several other names such as buttons or nubbins berries. They’re also called mutant strawberries, as well as monster or run strawberries. Unlike normal strawberries, deformed strawberries can contain scars, wrinkles or broken skins. Other deformities are strawberries with mold or decay or those that are either undeveloped or too ripe.
Nubbins or Button Strawberries
Damaging external agents are usually the causes for nubbins strawberries, which are also called button strawberries. For example, injury from cold weather can damage a flower’s pistillate or female parts. On the other hand, exceptionally hot weather can result in a lack of pollination, which can lead to a strawberry failing to develop properly. Nubbin strawberry deformities can also be due to nutritional shortages, such as not enough calcium.
Strawberries that look like a cockscomb or a cat’s puckered cheeks are also called fasciated or cat-faced strawberries. These deformities are the result of strawberries that have grown together as one plant with several tips or strawberries that have been fused together. This problem can be caused by dry, cold fall weather or periods of short daylight during autumn. Usually, cockscomb strawberries occur on plants that are adapted for growing in Northern regions, but instead grow in Southern areas.
Cyclamen mites feeding on strawberry plant leaves can cause leaf deformities. Leaves can develop to almost a full size when there’s only a small amount of cyclamen mites, but when there's a large population, these mites can cause deformed, wrinkled leaves that are somewhat darker than normal, noninfected leaves. These pink or amber-colored microscopic mites are shiny and oval-shaped. This pest can also affect the quality of fruit when left uncontrolled.
Considerations and Warnings
Injured strawberry seeds can cause fruit to be deformed. Injuries from seeds can be due to lygus bugs that that feed on plants and blemish them. Weed strawberry plants in winter when lygus mites are still in their nymph stage. Other causes of injury to seeds can be from light frost or poor pollination, resulting in seeds being smaller than normal.
- University of Missouri Extension; Home Fruit Production; Michele R. Warmund; May 2010
- Purdue University; Commodities Strawberries; B. Bordelon; 2003
- University of California; Lygus Bug and Its Management in Strawberries; Surendra Dara
- University of Minnesota; Strawberry Insect Pests of the Home; Beth R. Jarvis; April 1999
- University of Minnesota; Strawberry Insect Pest Management; Sujaya Rao; November 2009