This is my first stab at a hydro grow using Rumpleforeskins bubble bucket design, the Lucas Formula and clones taken from a white widow. Growth has been good - both roots and leaves. I am about 9 days into veg and noticed rusty brown colored spots on the leaves. They do not come off when rubbed (see picture below). I am thinking it's a calcium deficiency but have not eliminated the possibility that I am doing something else wrong (being my 1st hydro grow). Any opinions and/or advise? Since I noticed this I have been foliar feeding with water with some calcium chloride (about 1/2 tsp per litre). Thanks in advance. X
What does the back side of the leaf look like. If it what they call "rust" it is actually a fungus and the back side should have spores on it. Do you mist your plant? What is your Humidity? If you do not know the humidity in the room, what is the humidity where you live?
Thanks for the reply! The back of the leaves looks fine. No spots or discoloration at all. They look perfectly normal. I generally do not mist the plant - the only exception being to foliar feed with the calcium solution I described above. Humidity is generally between 20% and 35% - never ever more than 35% If it were a fungus, shouldn't I be able to rub some of it off? X
If it a fungus then the spores will be on the back of the leaf, Ya you should be able to wipe the spores off. If it is a mold the top side "rust" is the damge from the mold underneath. Now if it is not a fungus, shit, maybe it is magnesium deficiency. Is your ph good, and has it been good?
I check pH daily. It's been steady at 5.6. I have also added some epsom salts to the mix in case it is a magnesium or sulfur deficiency. I also went ahead and misted with a baking soda solution (1 tsp per litre) in case it is come sort of fungus. X
I'm sorry, I am not sure then. I wish I could help more, good luck. If you find out, I would like to know.
My veg plant was suffering from the same rust spots you talking about. However, I purchased some Cal-mag to buffer out the reverse osmosis water I use on the plant and all new growth on the plant looks delicious and healthy. I really think the rust spots developed when the plant was not getting enough calcium/magnesium from the RO water. Are you using filtered water? and if so, what kind?
I am using de-chlorinated tap water. Water where I live is very, very good. I have already supplemented with calcium chloride and epsom salts (magnesium sulphate). These should take care of any calcium, magnesium or sulphur deficiencies - yet the problem persists. I am thinking it's pH related now. I have a digital pH meter - but I am starting to question it's accuracy. I have been maintaining a pH of 5.6 (hydro) according to the meter - but I think the pH may actually be higher than that. I'm going to try lower my pH by 0.2 (according to the meter) to see if that helps. X
Buffer your pH pen in coca cola...it's pH is 2.3 or somewhere in that range just google it..did it for my meter when I got a bad buffer solution...you'll get a more accurate reading if your pen is dead on
What's the PPM? Having a pH of 5.8 if your pH reads 5.6 with a 0.2 difference shouldn't be a problem.
I agree... a 0.2 pH variance shouldn't make a big difference. I'm just tinkering to try to find something that works. Unfortunately. I don't have a PPM meter (money is tight right now as I am outta work). Thanks for the link 77401 - I already have two calibration solutions on hand. Trouble is, the pen itself is very basic. It's not even water proof. A couple of weeks back I accidentily dropped it into some water... so I had to dry it out for a few days. I suspect that there may have been some permanent damage though in terms of it's accuracy. A replacement is on it's way.
I have the same problem too. There is nothing that I can find anywhere with a clear answer. The only variable that is unaccounted for for me would be that foliar spraying may cause the light to magnify and burn my leavs other than that all is perfect. I'm also getting deformed new growthome which is upsetting too.