Solving Widespread Leaf Scorch and Drop in Alkaline Central Valley Soils

Diagnosis: High pH Nutrient Lockout

Multiple species (crape myrtle, aster, columbine, jasmine, potato bush, hibiscus) showing tip/edge browning and leaf drop as temperatures rise points to alkaline soil (pH > 7.5) induced nutrient deficiencies, especially iron. Central Valley soils are notoriously alkaline, and rising temperatures exacerbate pH-related unavailability.

Corrective Measures

Test soil pH. If above 7.5, apply agricultural sulfur, gypsum, or a soil acidifier per label. Begin a micronutrient regimen with chelated iron and a balanced fertilizer. Water deeply but infrequently to avoid waterlogging in clay soils.

Long-Term Strategy

Incorporate organic matter annually to buffer pH. Select species tolerant of alkaline conditions for future plantings. Monitor new growth for greening as an indicator of success.