Identifying and Managing Mold-Like Growth in Arizona Soil

What You're Seeing

The white/yellow growth with musty odor in your Glendale, AZ yard is almost certainly saprophytic fungi decomposing buried wood debris—mulch, sawdust, or construction lumber incorporated during landscaping. Common in new developments where topsoil is amended with wood products.

Two Management Approaches

Option 1: Accelerate Decomposition (Recommended)

• Apply nitrogen fertilizer: 5 lbs 29-3-4 or 15 lbs 10-10-10 per 1000 sq ft
• Water deeply to activate microbes
• Fungi will consume wood completely in one season
• Result: enriched soil with excellent organic matter

Option 2: Soil Replacement

• Remove and replace top 6 inches with quality loam (30-40% replacement)
• Immediate but expensive; loses organic matter benefit

What to Expect

• Temporary yellowing of new grass as microbes immobilize nitrogen
• Supplemental nitrogen may be needed during establishment
• By next season, soil will be highly fertile and well-structured
• Odor dissipates as decomposition completes

Fall Planting Advantage

Delay seeding/sodding until fall (October in AZ). Cooler temperatures reduce fungal activity and water demand while allowing root establishment before summer heat.