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Physan 20™ All Purpose Disinfectant


Broad range disinfectant, fungicide, virucide, and algaecide - R3620

Use Physan 20 to control fungus (damp-off) virus, bacteria, mildew and algae in your greenhouse. Disinfect cutting tools to prevent transfer of disease, and sanitize your pots and flats. Protect cuttings and bulbs by soaking briefly in Physan 20. Control mildew, rust, black spot, and gall on roses and extend cut flower life. Also use to control algae and fungus in evaporative coolers. Physan 20 is a concentrate that mixes easily with water, and does not leave residue marks on foliage.

Adult Plants - Spray any time disease other than rot is evident. Spray once / month as preventive maintenance. Soak compost when fungus is evident. Also use for Botrytis, Crown Rot, Dividing plants and Rot. Detailed instructions included and available at

Can be used on polycarbonate panels. Mixing ratio: 1/2 ounce to 1 gallon of water.

(1 pint concentrate)

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  • Use on some plants, greenhouses and equipment, tools, fountains, cuttings.
  • Especially good on low light plants, such as phalaenopsis. Use after every watering.
  • Not intended for food crops.
  • Toxic to fish.
  • Corrosive.
  • Prevents odors.
  • Will control algae in nozzles.
  • Do not enter enclosed area for 12 hours after using.

Q:  Can Physan 20 be frozen and then used when thawed?
A:  Yes it will be fine. Shake the bottle so it will reconstitute.

Maril's Physan 20 Plant Application Guide PDF

Physan 20 disinfection and algae control in the greenhouse PDF