Upping my proactive treatment game

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Well-Known Member
Apr 12, 2014
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If you have a greenhouse and have had it very long you surely have reached the 'i need a treatment program' phase...

I finally hit that about 5 years ago, when some conversations with Martin Motes and his book on florida orchid growing re-directed my thinking. Now that i have been doing 'somethings' for a few years and am seeing significantly improved results, I'm looking for the fine tuning kinds of things... like rotating the mode of action in the treatments so that the stuff i'm treating doesn't become resistant to that treatment.

So the question(s)

i use thiomyl (1) (spray)/Banrot (1,14) (drench) and Pageant (7,11) (spray and drench) as periodic prophylactic treatments for fungal/bacterial concerns. I'd like to add another treatment with a different mode of action. On an old spreadsheet from Sue Bottom i see Palladium and Switch as (9,12) modes. Anybody have direct experience with those or suggest any alternatives?

also as i'm just now re-consuming that Sue Bottom resource... i'm realizing that quaternary ammonium products and hydrogen peroxide sprays are suggested for erwinia (which i am always fighting in some small volume) Anyone using either of those treatments with correlate-able results?

I suspect there are also some 'natural' treatments for eradicating erwinia, but given the rest of the stuff i'm using i'd suspect that if the natural stuff is living in any way, the other treatments may put the natural creatures to rest. ;-)
Rich, I am not a fan of any preventive treatments of curative products, be they insecticide, miticides, or fungicides. Diseases come from the environment, so doing so is a lot like regularly taking pain killers because you know you’re clumsy and likely to stub your toe, or antibiotics in case you might get an infection. A better tack is greenhouse cleanliness and proactive, rather than preventive, treatments.

Erwinia is a systemic infection. Both hydrogen peroxide and Physan are topical disinfectants, so are not particularly good curatives. As far as I’m concerned, their best application is to be sprayed all around the structure, glazing, framework, benches, and floor, as a way to knock down the population of pathogens in the growing environment.

When I had my greenhouse in PA, I experimented by putting a low dose (1/4 - 1/2 tsp/gal) of Physan in my RO tank. It did appear that it reduced the number of rots, but I got away from that for two reasons. The first was that I had to disable the automatic refill of the storage tank, or the repeated water depletion and refilling would gradually dilute the Physan more and more, without me being able to know the concentration, which created its own issues. The second was the introduction of probiotics into my regimen.

Microbes are a fact of life, both good and bad. Your “preventive” fungicidal treatments kill both.

For the last several years, before I sold the greenhouse and moved to NC, I was using a monthly treatment of Inocucor Garden Solution as a drench, enhancing the population of beneficial microbes, and used Oxidate 2.0 (a horticultural hydrogen peroxide product) to disinfect the “environment” of pathogenic ones (not the plants) about every 6 months.

As I now grow in my home, with summers out on my deck (periodically washed, with the house, with bleach to knock down mildew), I have discontinued my use of a Physan, but the plants still get probiotics regularly. I have not had a single rot in over a decade. That applies to my orchids and the bedding plants that live in flower boxes and around my yard, and my tomatoes and herbs.

There is no question that Martin Motes and Sue Bottom are quite knowledgeable - I refer the the St. Augustine OS website all the time - but do consider that they are both in Florida, where the environment outside of the greenhouse is an ideal incubator for all sorts of pathogens that can easily invade the greenhouse, so they might otherwise be fighting a losing battle, so have to use the poisons.
Understood, and thanx for your replies…. Greenhouse density is a factor here for sure. ….

The journey continues :)
Rich, have you given any thought to adjusting your feed water rather than throwing all these chemicals around?
I personally don't have a need for most chemicals after the fact, as in rot.
I was plague by rot up to a year or so ago when it was suggested I try adding potassium silicate to my water. I add just a pinch to 55 gal of water every other time and I haven't seen rot since.
Well supposedly silicate is taken up and incorporated into the cell walls giving rigidity. The end result is a stronger plant, less floppy and resistant to bacterial attack. I'm no expert in biochemistry but it makes sense to me to keep all the other chemicals, NPK, in check as well. High nitrogen only serves to feed the microorganisms in the media so I keep it low. I haven't checked my TDS in a long time, 100-125 in rain water the last time.
I must add, the 100-125 is made of rain water approx 30 TDS from what is collected off my roof. Approx 5 gal of city water to bring the volume up, which is terrible at 550 to 700 TDS, the rest I add.
Plant nutrition is an extremely complex subject, and what applies to plant “A” may be significantly different for plant “B”. Then there’s the fact that there can be many nutritional changes that give near identical outcomes, good or bad.

Dyna-Gro pushed the silicon thing to sell ProteKt. The literature calls it a “nonessential” nutrient that “seems” to provide resistance to (under) watering issues. Marschner, who literally wrote the book on plant nutrition, states that it’s only essential in grains like rice. That said, there has been so little research on orchids (and if so, likely phals) that it’s anyone’s guess if there is a true scientific impact or a just perceived one.

When I started using RO water, I was a Dyna-Gro distributor. I used their “Grow” formula via a metering pump, so adjusted the solution pH by injecting ProteKt via another. Did that for about a decade, but observed no changes when I switched to doing that, nor when I switched to using MSU only.

We orchid growers, in my opinion, are second only to pot growers in seeking the “holy grail” of nutrient combo’s. I have been one of the worst in that regard - I suspect my interest in chemistry and my career in that industry leads me to ask “what can I throw at it to make it grow better?”. The truth of the matter is, however, we have the relatively the simple goal of “not too little and not too much” of anything.

This is starting to sound like an orchid society lecture, so I’ll stop now.
I like lectures. Please continue Ray. I've found over the years that K-Lite is the
answer to most everything orchid. Well, and not going crazy buying plants so
that the grow space is crowded. I use 1 tsp. to 7 gals. of water every watering
and it works very, very well with no issues. Thank you, Sir!

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