Phytophthora foot & root rot
Some of the best evidence indicating a Phytophthora disease are symptoms shown by the plant itself. Knowledge of the plant’s susceptibility is also helpful.
It is necessary to thoroughly examine above- and belowground parts of the plant. Aboveground symptoms are useful but not completely diagnostic. Many different problems can result in the same aboveground symptoms as Phytophthora root rots. Anything that girdles or cuts off water and nutrients to the top of a plant results in wilting, leaf chlorosis (yellowing), leaf necrosis (browning), and premature leaf fall and plant death. Causes include feeding by root weevil larvae, winter injury, mechanical injury, wire or plastic used to keep trees straight after planting, nursery tags, lack of water, and other fungal root rots as well as Phytophthora root rot.