brown rust spots on leaves?

[Chimsha]

Hi Guys,

I'm new to the forum and new to growing, I have 3 plants growing in soil on the terrace. All 3 plants have leaves with brown necrotic spots on their leaves. Not all leaves are affected but those that are can be older, lower leaves or newer growth. I am growing in Biobizz light mix, and have been very sparing in adding nutrients: every other watering I've added 1-2 ml per litre of Biobizz grow and added Biobizz root juice when they were seedlings. The plants are autoflowering and just entering week 6. Flowers are just beginning to form. I can't see any pests although a couple of weeks ago I thought I might have spider mites, I sprayed leaves with mixture of alcohol & water and also used Potassium soap. I can't see any signs of insects now. Could this be due to calcium lockout or calcium/magnesium deficiency? I did flush the plants with PH'ed water a couple of days ago. Should I use a calcium magnesium supplement?

I would really be grateful for any expert advice,

Thanks,

Chimsha

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[M_C]

Looks a little like a phosphorous deficency

[cheese brain]

Or gnats bro check ur topsoil let it dry out

[cheese brain]

Or gnats bro check ur topsoil let it dry out look droopy tho so overwaterin is a cunt

[Chimsha]

Hi Guys, Thanks for your suggestions. I showed the pics at my local Grow shop and they also tend to believe it could be due to overwatering. Will let them dry out and see what happens.

[HeebyJ]

I heard rust spots and thought Calcium deficiency. I'm more expert at having the problem than fixing it but a plain water to thin out any excess fertiliser could be good. Then a top up with calcium and magnesium but you really have to know what you've done to the plant to get it this way.

Is there not enough ferts in the soil ? The PH could be locking out essential phosphorus or calcium or magnesium. There's a great chart somewhere online under 'deficiencies cannabis' if I remember my googling.

You have to know if it's had too much fertiliser (cal/mag/phosphor possible other element) which is upsetting the root, or not enough, so think how much grow nutrients you've been using and thin them out if you need to with a plain ph'd watering cycle.

Good Luck Maan!

[Chimsha]

I heard rust spots and thought Calcium deficiency. I'm more expert at having the problem than fixing it but a plain water to thin out any excess fertiliser could be good. Then a top up with calcium and magnesium but you really have to know what you've done to the plant to get it this way.

Is there not enough ferts in the soil ? The PH could be locking out essential phosphorus or calcium or magnesium. There's a great chart somewhere online under 'deficiencies cannabis' if I remember my googling.

You have to know if it's had too much fertiliser (cal/mag/phosphor possible other element) which is upsetting the root, or not enough, so think how much grow nutrients you've been using and thin them out if you need to with a plain ph'd watering cycle.

Good Luck Maan!

Thanks Heeby 3, Will follow your suggestions!

[Hobby420]

Like Heebyj, I am good at creating problems :-) I just had a similar issue with one of my girls which looks to be about the same age as your's. My issue was in the roots. I have 4 plants but the one that started first was about a week ahead of the others. I started to have that problem with the oldest one and when I transplanted it, it was much more root bound than the other three. Root issues can present as all sort of deficiencies. I have also caused it by overwatering, as others have already suggested. This grow, I am letting them dry out completely, an idea I got from the White Widdow video from the greenhouse seed company. Just my two cents worth....

H420

[Hobbit]

Looks like over watering and a ph issue as well. Dont ph your water or nute in soil mate and let them dry out b4 watering and feeding.

[dickiefickle]

Overwatered . Don't pH the water when growing in soil , as the soil buffers for you . dry out well (you can tell by lifting the pots )