Knowledgebase
Fish fertilizer and mold #739343
Asked March 16, 2021, 4:40 PM EDT
I started a lot of tomato plants from seed in little seed pods and they’re under a grow light. They were looking great until I fertilized them with a fish and kelp fertilizer and within a day or so they became extremely moldy. What happened? Can I still save them?
Jefferson County Colorado
Expert Response
I think you'll be able to save them without too much trouble. This may* be a type of saprophytic fungus which feeds upon dead and decaying plant material and can even live in many potting soils. One concern though is a disease called Damping Off which is essentially due to certain fungi infecting young seedlings; it often presents as a "pinched" area near the bottom of a seedling's stem, it will turn it blackish and sometimes kill a seedling over time (images in the 2nd link below). I am not seeing this in your picture, and from your message it sounds like the fungus appeared only after applying the fertilizer. I cannot be certain what kind of fungus you having growing on your soil, but one thing that can sometimes help is to reduce humidity and watering. Definitely provide the seedlings with water, but try not to allow the soil to consistently remain moist; this can slow down the growth of the fungus while still supporting the seedlings.
More information on fungi as they related to plants can be found on page 3 of this document:
https://cmg.extension.colostate.edu/wp-content/uploads/sites/59/2020/01/GN-330-Plant-Pathology.pdf
More information about Damping off can be found on this page from Minnesota Extension: https://extension.umn.edu/solve-problem/how-prevent-seedling-damping
Sent from my iPhone
On Mar 18, 2021, at 5:07 PM, Ask Extension <<personal data hidden>> wrote:
This blog post from Iowa State Extension provides much more information regarding the first topic you asked about : https://hortnews.extension.iastate.edu/2018/10/can-sick-plants-make-people-sick#:~:text=Garden%20produce%20from%20a%20sick,bacteria%20can%20produce%20toxic%20compounds
It is difficult to say whether you tomatoes might benefit from an additional round of fertilizer because this also depends upon the soil you used and its composition. And so for these reasons, I generally recommend soil testing before making any hard suggestions for fertilizing. We do have some general guidelines for tomatoes!
Page 5 of this document provides more information for fertilizing tomatoes: http://adams.colostate.edu/hort/docs/Growing%20Tomatoes.pdf
And if you are interested in soil testing, more information can be found here on the CSU lab's website: http://www.soiltestinglab.colostate.edu/
