Dwarfs and the endless procession of blossom drop

[z_willus_d]

Hello, I'm looking for insight. Several months ago, I started an indoor winter garden made up of all New Dwarf varieties: Rosella Purple, Mr. Snow, Summertime Gold, Summertime Green, Beryl Beauty, and Tasmanian Chocolate -- 12 plants in total, housed in pairs in Raybo's 18 Gallon InnTainers. Things started out well, and after a little over a month after transplanting up to the InnTainers, I had several fruit set on the Rosella Purple, Summertime Gold, Beryl Beauty and the Tasmanian. Temps started to cool in the garage (hitting lows around 50F at the coolest part of the nights) , and I entered a 2 month phase where no more fruit set and I had literally 100+ blossoms drop. I'm not sure if the temperature can be blamed for the dropped blossoms, but to be safe I added an oil-filled heater to the garage and along with the requisite increase in my electricity bills, the temperature also increased to a range of 60-80F 24-7. I also added small 50W aquarium heaters to the water reservoir of the InnTainers. Things are nice and toasty now.

So it had been over two months since a fruit had set, and then I got a couple fruits to set on the four Rosella Purple plants, but no other of the plants have set a fruit in months. Every day I recover 10 sometimes 20 dropped blossoms from the grow area and below the plants on the soil. In general, the plants look amazingly healthy, robust, loaded with flowers (what's left before they drop), and in all apparent ways, save one, seem to be perfectly fine.

Recently, I noticed that some of the lower leaves had contracted what looks like a drying mildew or fungus. The branches with those leaves fall off and the problem is spreading upwards slowly. The humidity used to be on the low side, so I was running a humidifier to bring it up to around 40%, but for the past month or so humidity has been 50-65%. The space between plants has reduced to less than zero as they've filled out, so with the humidity and lack of room to spread, I'm not surprised with the fungus/mildew issues. I've sprayed Actinovate and when that failed to help, I applied Daconil. So, I'm in a battle with that problem. I run an oscillating fan 24 hours on a low setting to try and keep a breeze running through the plants.

As for what I've filled my InnTainer containers with, I'm using the same mix that Ray Newstead (Raybo) has tested and employed with great success (over 50 tomatoes on one Mano plant!). It's a mix of Perlite, Sunshine #4, and decorative mirco bark with a cup of dolomite lime, a about a cup of tomato tone in a strip, some epsom salts and, in my case (not Ray's), trace amount of homemade worm-castings. After first transplant, I used a dilute amount of Tiger Bloom with each watering (about once a week), but I cut that out after the first sign of blossom drop. Maybe three applications with the water in total. I also spread 1/2 tsp per plant of Calcium nitrate crystals and watered in from above. That was long ago as well. Since then, no fertilizers added. Ok, well almost none. I did a foliar spray of Actinovate and kelp extract. A couple weeks back, I did a soil drench with Great White Myco, Roots Excelurator, MycoGrow, Biota, and Actinovate. That added no Nitrogen, but was meant to address the fungus problem and help boost the root system, etc.
I have an enthusiast grade pH meter, and it indicates the pH in the Tainers ranges between 5.6 and 6.6 depending on the Tainer and my measurement. It is very curious that the two tainers that measured at 6.33 and 6.56 happen to contain the four Rosella Purple plants that seem to be doing best. On the other hand, Mr. Snow plants that haven't set a single fruit are in the lower pH bins at 5.61 and 5.58. Could the lower pH be source of my problems? If so, what could I do to correct it with the plants in? Water with pH up solution?

I know that stress is usually to blame for blossom drop -- temperature too high/low, disease, over Nitrogen, nutrient deficiencies, etc. I know the plants are fighting a bout of fungus/mildew , but I think it's reasonably under control. BTW, any ideas exactly what that is based on the pics? I've got my temperature dialed in. I think humidity is a bit high. I'm concerned about the pH? What else haven't I considered. I've spent countless hours on this winter garden, let's not mention the cost, so getting through all this with only a few meager, sad tomatoes will be a major bummer for me. It's even more insulting since the plants are so seemly healthy and robust, except for the fungus issues. I need your ideas.

Thanks for helping out!
--naysen