Strawberries do not require, but benefit from, insect pollination, so weather conditions that limit insect activity and pollen movement typically precede when this type of misshapen fruit appears.
|Misshapen strawberry fruit due to poor pollination (above) and a normal appearing fruit (below). Photo: HJB|
Lygus bug injury
North Carolina Department of Agricultural (NCDA) regional agronomist David Dycus mentioned via email today that growers in Mississippi had recently expressed concern about misshapen fruit due to lygus bug feeding. Lygus bugs (also known as tarnished plant bugs) feed on strawberry seeds and fruit and can also cause misshapen fruit. Lygus feeding does not result in variable seed size and can, therefore, be distinguished from poor pollination in strawberries. Typically, North Carolina growers do not experience extensive damage from lygus bugs, because they are active later in the year. This year, however, they may be active earlier (although, our warm spring has turned a little chillier), and it's worth keeping an eye for their damage. Lygus can be difficult to control, so if grower suspect they have damaging populations of lygus present, they should contact their county agent or myself for recommendations.
|Strawberries damaged by lygus bugs. Photo: UC IPM Program|
Other causes of misshapen berries
Insects and poor pollination are not the only causes of misshapen fruit in strawberries. Pathogens can damage fruit, mechanical injury can scar it, and abiotic factors can change fruit shape.
Update, 27 April 2013
An update to this post has been added to the NCSU Strawberry Growers Information Portal.