The Essential Guide to Fungicides for Warm-Season Grasses

Identifying Common Lawn Diseases in Warm-Season Grass

The path to effective treatment begins with identifying the culprit. Warm-season grasses are susceptible to various diseases, including Dollar Spot, Grey Leaf Spot, Take-All Root Rot, and the notorious Large Patch. Early detection and identification are crucial for effective control and eradication.

Dollar Spot:

Dollar Spot is a common fungal disease that manifests as small, silver dollar-sized straw-colored spots on the lawn. It thrives in conditions of high humidity and moderate temperatures. Early morning dew or over-watering can exacerbate the situation.

Identification:

• Look for small, straw-colored spots ranging from the size of a silver dollar to the size of a dinner plate.
• Upon closer inspection, white, cobweb-like mycelium may be visible on the grass blades, especially in the mornings.

Control:

• Avoid excessive watering, especially in the evenings.
• Employ a balanced fertilization strategy to improve turf vigor and disease resistance.
• Fungicide applications may be necessary in severe infestations or as a preventive measure in historically problematic areas.

Grey Leaf Spot:

Grey Leaf Spot disease is caused by the fungus Pyricularia grisea, predominantly attacking St. Augustine and Bermuda grass varieties.

Identification:

• Look for tiny, brown spots on young leaves, which eventually enlarge and become greyish with dark brown margins.
• Severely infected turf may appear scorched.

Control:

• Avoid over-fertilizing with nitrogen, which can promote disease development.
• Water the lawn early in the day to allow the grass to dry before evening.
• Fungicides can be used as a preventive or control measure, with applications beginning in the early summer.

Take-All Root Rot:

This sinister disease is a soil-borne fungus that affects the root system, often leading to extensive damage before above-ground symptoms are evident.

Identification:

• Initially, grass may exhibit a yellowing or browning of the leaf blades.
• As the disease progresses, large patches of dead grass may appear.

Control:

• Maintain a balanced soil pH through proper fertilization.
• Avoid excessive watering and improve soil drainage to create a less hospitable environment for the fungus.
• Fungicides can be applied as a soil drench to infected areas.

Large Patch:

Large Patch disease is particularly nefarious, causing large, circular brown, sunken, or dead grass patches.

Identification:

• Look for circular patches of dying or dead grass, often expanding to several feet in diameter.
• The outer ring of the affected area may appear orange or bronze.

Control:

• Refrain from over-watering and ensure good drainage to prevent waterlogging, which favors disease development.
• Fungicides can be a crucial part of the management program, especially during the fall and spring when the disease is most active.