Leaf Spot Fungus and Identifying a Grassy Weed

Managing Leaf Spot in Clay Soil

Leaf spot—small moldy, rusty, or powdery lesions on blades—is a fungal disease encouraged by overwatering, especially on heavy clay soils that stay wet.

Action Plan

1. Reduce irrigation: Water deeply once weekly (1–2 hours) rather than frequent light cycles.
2. Apply fungicide if needed: Use products labeled for leaf spot; mancozeb or similar.
3. Consider upgrading grass: Modern tall fescue cultivars (e.g., 'SR-8600', 'Rembrandt') offer better disease resistance.

Weed Identification

Your description—tight, stalk-like stems with a "knee joint," straw-like feel—suggests carpetweed (Mollugo verticillata) or bedstraw (Galium spp.). Both are broadleaf weeds.

Control

• Use a broadleaf herbicide containing 2,4-D, dicamba (Trimec), or bentazone (e.g., Ortho Weed-B-Gon).
• Prevent flowering and seed set to reduce future populations.

Search USDA Plants Database or Google Images with the botanical name for confirmation.