We’ve been struggling to get our basil bed to grow properly. We have done water tests and tried to adjust nutrient and pH levels in our beds. But I think we’ve finally figured out why we keep getting chlorosis (yellowing in the leaves). Pythium.
The thing about root diseases is that they can keep plants from getting the right nutrients, so the plants show signs of chlorosis, because although the nutrient might be in the water, the plant cannot absorb enough of it.
I should have figured this out earlier. I had chlorosis, but it was very uneven. Usually nutrient problems affect the whole crop similarly. Diseases tend to be much more uneven.
Also, I had had pythium in one of the basil beds a number of weeks ago and thought we had dealt with it then, since we took the plants out, removed the plastic and washed then bleached everything. Not enough, though, I guess.
I am starting to be suspicious of our germination chamber. We have been getting really uneven and poor germination in our basil for a while, and we cannot figure out why. I haven’t seen a typical example of damping off (the disease pythium is one of the pathogens that causes damping off). But I think it is affecting the roots which seem to have poor and uneven growth in the last few months and I have been trying to adjust watering, heating and other issues, because that I what I was (foolishly, it turns out) assuming my problem was.
Pythium has many species. Some are specific to certain species (I really hope that this one is specific to basil). Some are pathogens that infect a wide range of plants. Most of the species, though, are able to live on dead plant material for a long time making it quite difficult to control.
To control it, I am going to take every part of the process that we use in the life cycle of the basil and clean it.
– the propagation area needs to be dissembled and cleaned out.
– the aeration stones and piping needs to be disassembled and soaked in bleach solution.
– all of the float rafts need to be cleaned with an extra good disinfection process of bleaching for a long time.
– the float bed plastic needs to be removed and the under-layer cleaned and disinfested.
– the tables where the plants are kept after germination but before being put into float beds need to be bleached.
– all of the young seedlings need to be discarded in case they were contaminated.
It will probably be several days of person hours to deal with all of this. I just don’t see a good alternative. The next problem will be trying to establish a way of cleaning the beds more as we go. You can see the algae in the picture of the roots. Although that algae is really only at the ends of the beds, where there is light, it is a serious problem. It can harbour some pathogens itself, and it uses up nutrients and dead algae is a part of the detritus (dead organic material) that collects on the bottom of the pools. This dead organic material is a good home for pythium, and it is a place that bacteria collect and use up oxygen as they break it down. That oxygen use can significantly affect productivity of our crop.
I am thinking about adding an ozone generator to my grow beds–especially the basil. But for now cleaning is the priority. I hope I can get this under control.