hydroponic green beans
I am using an "ebb and flow" hydroponic system in a temperature and light controlled garden room (day temp 75-80; night temp 65; HPS lights 13 hrs/day) to grow bush green beans (variety = MAXIBEL). I have grown this variety for years. This year the plants have developed what looks like bacterial brown spot. The problem starts on the lower leaves, which then turn yellow and drop off. Conditions in the
Lincoln County Oregon
This doesn't look like characteristic bacterial brown spot. (Bacterial brown spot usually has very dark brown or black centers to the leaf spots).
Your initial question got cut off-can you provide the information again?
What is your seed source? How did you start the seed? How long have the plants been in the system? Any changes to the lighting or temperature? Any changes to the nutrient solution used, timing or pH? Have you sprayed the foliage with anything or made any pesticide treatments? Any you seeing any insects?
I had spoken of the problem with a troubleshooter from the seed company(Johnny's seeds, Maine)- after exhaustive discussion (and with your comments in mind) he suggested the problem may be low nitrogen. I have always used a low nitrogen formula for beans. This is what is generally suggested. However, once I thought about it, low nitrogen would fit the profile of the symptoms I have- yellowing of lower leaves, lack of bright green in middle leaves and normal green upper growth. I have therefore changed the fertilization formula to 1:1 growth, flowering components. I have also increased the hours of light from 13 to 16. Hopefully this will resolve the problem.
FYI: Enclosed garden room with temperature control and 1000 watt HPS bulbs; 65 degrees night and 75-80degrees day; ebb and flow hydroponic system, seeds from commercial source-Johnny's Seeds, controlled pH, no insecticides used.
That's great-I hope that the fertilizer change solves your problem!
Good luck and thanks for using Ask-An-Expert!