Monday, April 4, 2011
In spite of all of the precautions I take, about two weeks ago I noticed that my tomato seedlings were showing signs of damping off.
This fungal condition, known as Pythium wilt, is found in soil and growing mediums, and it can also be transmitted by air and contaminated tools.
I guess I was in denial, as I watched the condition progress for several days hoping that I was mistaken. Then, on Sunday March 27, 2011, my beautiful ,expensive, seedlings began to topple over.
My authoritative greenhouse gardening book says: "Once initiated, damping off is fatal. At the onset of damping off, the stem looses girth at the soil line, weakens, then grows dark, and finally circulation is cut, killing the seedling or cutting." And, that is exactly what was happening to my seedlings. Consulting other gardening books I found no cure for this condition, and the advice given was to remove and destroy the seedlings.
Immediately I started a replacement batch of seeds in rockwool cubes, thankful that I had plenty of time as it is still early in the season.
I was still hesitant to destroy my diseased seedlings, as the tops, above the diseased stem, were green, healthy and growing. My first thought was to cut off the tops and clone them, so I Googled cloning tomato seedlings that had dampened off. If anyone had tried it, they had not put anything on the web concerning it as I found absolutely nothing.
Well thought I, why not give it a try? First I sterilized a pair of surgical scissors and then soaked enough rockwool cubes in a solution of Capitan to accommodate the seedlings. I cut the seedlings about 1/4" above the diseased area, and dipped the cutting in the Capitan. While still holding the cutting under the Capitan solution I used a sterile scalpel to place a 45 degree cut above the first cut, this was done to prevent an embolism from forming in the stem. The cuttings were then dipped in rooting hormone and placed into the rockwool. Isolating the cuttings, I placed the cubes under a dome, and the dome under the red/blue/white LED for 14 hours a day. Finally, I added CO2 and a heat mat to complete the cloning attempt.
Much to my amazement, and relief, the cuttings rooted in only six days. So, six days after the first seedling toppled over, the seedlings were repotted in sterile potting mix and back under the LED, minus the dome.
As I would expect, there is some minor yellowing on some of the leaf tips, but that is typical with cuttings. The good news is that I can already see vertical growth, and that is an indication that the roots are working and a transport system is in place and functioning.
On Sunday, April 3, 2011, one week later, the seedlings were back in the greenhouse enjoying the sunshine and eighty degree heat. As we are now in a cool, damp, rainy period, I am giving them several hours of light under a HID HPS and several hours under the LED.
I don't know if the disease was limited to the area infected, or if it is present in the tissue and cells of the plant, but I consider this a learning process, regardless of the outcome.
What I do not understand is that my pepper seedlings were planted the same day as the tomatoes, grown under the same conditions, and they did not damp off. The replacement seeds have started to germinate, so I may have more tomatoes than I know what to do with if this process is a success.
As usual, only time will tell the outcome of this project, but some of the cuttings are developing flower clusters, and that can be nothing but a good sign.