Routine flush with disinfectant, fungicide, virucide, algaecide…

[Jim S]

I’m back into orchids after a 40 year absence, and have been growing again for three years. All orchids are thriving, no disease, bugs or significant snow mold or algae – I want to keep it that way.

Does anyone do routine flushes with things like Physan 20? If so, how often, and is your “flush” mixture diluted when compared to a “treatment” mixture?

Thanks

[estación seca]

This is not a good idea. There is an ecosystem of many different organisms in the pot. They keep each other under control. Routine chemical treatment knocks down populations of beneficial organisms. It selects strains of harmful organisms resistant to the treatment.

The best ways by far to prevent disease are to provide proper growing conditions, and to keep the growing area clean. Plants stressed by too high or low temperatures, light and/or humidity are far more susceptible to diseases.

Using probiotics, such as beneficial mycorhizal fungi, may also help.

[Jim S]

Thanks, glad I asked.

[Dimples]

Welcome back! What types of orchids are you growing?

Plant science related to pathogens/pests/disease management has changed over the years, and preventative treatments are no longer suggested and are now being actively discouraged.

Exceptions include specific instances where the product is intended to prevent infection during environmental conditions that encourage the development of the disease (eg. Copper fungicide should be applied to tomato foliage BEFORE damp weather to prevent fungi from proliferating and infecting the plant - copper sprays applied after the disease has infected the tomato won't cure the plant).

Treating a plant that is not showing signs of disease/pest/etc. promotes the evolution of resistant strains of the pathogen/insect and reduces the effectiveness of the pesticide products when they are genuinely needed.

Provide good culture, and treat only when treatment is needed.

If you need to treat, always use the label recommended rate and application frequency. Using a more dilute concentration can accelerate the development of resistant pest strains/populations.

If you feel that you absolutely MUST use something routinely, use products that kill by physical methods (horticultural oils, horticultural soaps, etc.). Pests and diseases can't build up resistance to those in the same way they can to products that use targeted pathways.

[Jim S]

It's nice to be back growing, even nicer to have good results. I'm currently growing Miltassia, Cattleya, Brassavola, Aliceara, and my favorite to date, Psychopsis.

[estación seca]

We look forward to seeing flowers!