Injury developing in an Iris leaf

Injury developing in an Iris leaf
Injury developing in an Iris leaf

HF injury developing in an Iris leaf. Fluoride ions (F-) are carried to the margins and tip of the leaf where they concentrate. At high concentrations the fluoride causes membrane collapse and the cell contents leak - hence the “water soaked” appearance indicated by the arrow. • The affected cells die and the tissue dries out, changing colour. In Iris it is usually tan-brown. In some species a darker brown line develops  between the green and necrotic areas but it does not always occur. •This leaf has bands of necrosis due to it being exposed to to several distinct fumigation episodes. •Note that the effects of the fluoride are usually  restricted to the tissues immediately around the area of visible injury where concentrations are extremely high. Adjacent green tissue may function normally.