It's easy to spot an amaryllis with a virus as it will have light green streaks among the normal green color of the leaves.
I knew that heat treatment had been done on other varieties of plants with good success. What was not agreed on was the amount of heat necessary. It had to be high enough to kill the virus but not high enough to kill the plant. I found examples in the 35-37 C range. I have seen others claiming that one hour at 110F would destroy virus infections. This had to be "core" temperature and not air temp.
OK, so on to our "redneck" heat box. I took a regular plastic storage box, made a plywood top, cut a couple of slots for cheap thermometers, drilled a hole for the meat thermometer and installed and wired a receptacle for the 100 watt bulb that was to be the heat source.
Here are the top and bottom shots of the plywood top.
For the test, I used these virused bulbs that had already been dried for about four weeks. This four-week drying period is what I use for all bulbs before repotting for the upcoming season. The bulbs are placed in paper sandwich bags and marked with the name of the bulb. As you can see in the next picture,one bulb was too large for the bags and was placed in a plastic pot.
You will also see a clay pot, upside down, in the box. This is for the sacrificial onion. The onion is for the meat thermometer to penetrate to the center so we have a good reference for "core" temp. This onion is larger than the largest bulb so when it's core temp is reached we can be sure the bulbs are heated through.
So what did I take away from this? First, it seems to work, at least in some cases. Of the eighteen bulbs only two have shown signs of virus after being planted for over three months. I will continue to watch the others as signs may not show up until the plants are under stress.
The box needs more heat as it took too long to reach 110 degrees in the core of the onion. I have added receptacles for two more 100 watt bulbs. It is much too early to say that this kills virus in bulbs. What we can say is, it shows promise and I will be conducting further tests. I will also be raising the temperature to 120 degrees for the next batch.
In addition, I have found a couple of other uses for the heat box. Since adding the two other 100 watt bulbs I have been able to sterilize clay pots and have also used the box as a "heat mat" for starting seed.
Follow up. Two months ago I ran this test again with different bulbs and with some Brugmansia cuttings I knew to be infected. Everything was the same except the temperature was raised to 120 degrees at the core and held there for one hour and twenty minutes. None of the bulbs showed signs of damage from the heat and none have shown signs of virus to this point. I will now be treating all of my bulbs each fall as I believe this treatment has definite value.