Phytophthora Root Rot

Phytophthora is a disease that attacks the fine absorbing roots of plants and may invade larger roots and the root collar.  These fungi grow in the cambium and sapwood causing death of the tissue.  Loss of water and nutrient absorbing capacity in the root cause a gradual or sometimes rapid decline of the plant.  Phytophthora is a water mold therefore diseases caused by these fungi are most common on soils that are poorly drained or receive excessive irrigation.  Plants with soil or mulch covering their root collar are very susceptible to root rot.  Symptoms include a reduction in shoot growth, small leaves, thinning of the crown, chlorosis, twig and branch dieback and eventually death.  Leaves turn red then brown and usually remain attached.