Leaf tip scorch symptoms on redwood trees are found from the lower to upper canopy and include healthy leaves interspersed with brown and grey leaves or portions of leaves. Grey leaves typically have black margins into the healthy tissue.
Such symptoms are typically caused by a fungus called Pestalotiopsis funerea. They are commonly associated with drought, when rainfall occurs or when there is overhead watering around the tree. Drought stress predisposes plants to being infected, so the increased moisture facilitates the infection process. Normally the fungus will only seriously affect sprouts, as branches of adult tress will regrow areas killed by the infection within a year. In nursery settings it is important to increase ventilation and avoid big differences in watering regimes to minimize symptoms.