Houseplant Leaf Damage: Pests or Disease?

I was wondering if you would know what would cause this type of damage to a leaf on a ZZ plant? I have several other plants with similar damage to their leaves including several calathea, crotons, and pothos. I’m assuming some type of pest, however, the only thing I’ve been able to spot is some fungus knats. Thank you for your time,

Hi Josh,


It’s hard to tell from these pictures what the problem is, could you describe the damage? Brown marks, yellow marks, circles, etc. Until I get more info, spray all parts of the plant with my Green Solution: 50% water, 50% inexpensive rubbing alcohol, a few squirts of biodegradable liquid detergent, a few squirts of mineral oil. Be sure the plants are not in the sun and the soil is not super dry. Protect carpets and furniture. This works well on many plant diseases and plant pests. (until we can determine the exact problem).