This is algal leaf spot. It usually occurs when the environment is overly humid after fertilizing or spraying liquid fertilizer. Algae or similar microorganisms like moss or seaweed in the air can settle on the leaf surface, forming green or dark green patches that may look like disease spots. However, these are actually algae colonies attaching and multiplying on the leaves.
To reduce the occurrence of algal spots, we recommend mixing a copper-based fungicide with your liquid fertilizer but do not mix it with other substances. Alternatively, you can mix either one of 25ml Mr Ganick Moldy Guard/ 25ml Mr Ganick Bact-X/ 10g Mr Ganick Tricho UV+ or 10g Mr Ganick Bacil UV+ into 20L of water.
This helps suppress algae, moss, and other microbes, while also preventing some fungal diseases. It’s gentle on plants and safe for regular use with fertilizers.
**Tip: In addition to treatments, reducing humidity and improving air circulation such as through proper pruning, can significantly lower the chance of algal leaf spot. During rainy seasons or in greenhouses, extra care should be taken to ensure good ventilation and dry leaf surfaces.
