Cause Algae (aquatic plants). Two genera are common: Symploca sp. and Oscillatoria sp. Algae grow where conditions are unsuited for growing a dense, healthy turf. Shaded areas with poor drainage, little air movement, and compacted soils are ideal for algal growth. Under those conditions, algae grow better than turfgrasses. The only permanent algae control is to correct the conditions unfavorable for grass growth.
Symptoms Dark, brown-black growth over the soil surface and plant crowns. May look like an oil spot.
Cultural control
- Improve soil drainage.
- Maintain good soil fertility.
- Loosen compacted soil.
- Provide for more light by pruning shrubs or trees.
Chemical control These give only temporary control. Identify and correct the causes of turf deterioration for more lasting results.
- Badge X2 at 4 to 6 lb/A. Group M1 fungicide. 48-hr reentry. O
- Concert at 3 to 8.3 fl oz/1,000 sq ft. Do not use on fine fescue turf. Group 3 + M5 fungicide. 12-hr reentry.
- Cuprofix Ultra 40 Disperss at 1 to 2.7 oz/1,000 sq ft/5 gal water. Phytotoxicity may occur depending on varietal differences. Group M1 fungicide. 48-hr reentry.
- Daconil Weather Stik at 2 to 3.6 fl oz/1,000 sq ft or at 5.5 fl oz/1,000 sq ft if algae are well established. Group M5 fungicide. 12-hr reentry.
- Encartis at 3 to 4 fl oz/1,000 sq ft. Do not use with oil-based pesticides. Group 7 + M5 fungicide. Reentry when sprays have dried.
- Grotto at 1.5 to 5.9 fl oz/2.3 gal water/1,000 sq ft. Group M1 fungicide. 4-hr reentry. O
- Jet-Ag at 1.6 to 15.5 fl oz/5 gal water.1,000 sq ft. Reentry when spray has dried.
- Junction at 2 to 3.6 lb/1,000 sq ft. Do not use within 5 days of sod harvest. Group M1 + M3 fungicide. 48-hr reentry.
- Mancozeb 80% (Fore, Manzate, or Protect DF) at 6 oz/1,000 sq ft. Group M3 fungicide. 24-hr reentry.
- Nu-Cop 50 DF at 3 to 6 lb/A. Group M1 fungicide. 48-hr reentry. O
- PERpose Plus at 1.6 to 10 fl oz/5 gal water.1,000 sq ft. 1-hr reentry.
- Previa at 2 to 5.5 fl oz/1,000 sq ft. Group M5 fungicide. 12-hr reentry.
- QuickSilver at 1 to 2.1 fl oz/A. Reentry when sprays have dried.
- Renown at 2.5 to 4.5 fl oz/1,000 sq ft. Group M5 + 11 fungicide. 12-hr reentry.
- Secure at 0.5 fl oz/1,000 sq ft plus another algaecide. Group 29 fungicide. Reentry when sprays have dried.
- ZeroTol 2.0 at 6 to 12 fl oz/1,000 sq ft. 1-hr reentry.
Note: Xzemplar is not recommended as it does not kill algae.
Reference Wong, F.P. and Rios, J.C. 2008. Evaluation of fungicides for suppression of algae in southern California, 2007. Plant Disease Management Reports 3:T007.