Soluble salt injury on geranium root

Notice damaged, dark colored roots on this geranium. Combination of controlled release fertilizer (see prills at top left of roots) and liquid fertilizer contributed to high soluble salts. Roots are just beginning to regrow after plants have been leached. These symptoms could also be caused by Pythium root rot. In many cases, injured geranium roots also have Pythium.

Fact Sheets
Basic Fertilizer Programs for Containerized Greenhouse Crops
pH and Fertility Review for Vegetatively-propagated Annuals
Root Diseases of Greenhouse Crops