Zippering is a physiological disorder that results in thin brown necrotic scars that runs along the fruit, eventually causing localized splits. The scars extend partially along the fruit over their length and width, occasionally connecting the blossom end to the stem in a zipper-like lesion, hence the name. Grooves into the fruit flesh and deformation of the surface are also common. The damaged tissue loses its elasticity and fruits are not developing properly. Once the damage is visible, it is too late to do anything.
Zippering is a physiological disorder, caused by low temperatures and high humidities during late flowering and early fruit set. During the development of the young fruit, one or several anthers remain attached to the ovary wall, causing fine scars on the outside of the fruit as it develops. Temperature sensitivity differs from variety to variety. Some tomato varieties are more prone than others, with Beefsteak tomatoes being amongst the worse afflicted.
No biological treatment is know against this physiological disorder. It can only be treated with preventive measures.
Always consider an integrated approach with preventive measures and biological treatments if available. This disease can only be treated by preventive measures.