strange rust patches

[Gangabiss]

I have 11 plants that are 16 days old from seed and about 3 of them have started showing strange rusty patches on the leaves and I'm starting to get worried.
They started showing up about 4-5 days ago on one of the plants and now a couple more are also showing the same symptoms.

I think I may have slightly overferted them at day 11 I gave them some very weak nutes (1/4 strength Bio-Grow) because I thought they could handle it...a couple of days later they all started showing very slight burning on the tips of the very bottom first leaves but apart from that they were fine. I've given them straight plain water since and they are doing fine exept for these strange rusty patches on a few of them.

I don't have a digi cam so I had to improvise lol

This is what it looks like:

I noticed that there were slightly shiny patches on some leaves before and I think that is where they end up going rusty.

I have noticed a couple of flying insects in my room before. They are long bodied (about 2cm long) and they are a florescent green colour. I killed them as soon as I saw them in case they caused a problem...could this be the cause of the rusty patches?
They are getting worse every day I look at them but I didn't notice any insects in there today.

Please help me!

 

[mace_ecam]

I noticed that there were slightly shiny patches on some leaves before and I think that is where they end up going rusty.

enough K but not enough Mg

by plantbuilder https://cannabis-world.org/cw/showthread.php?t=707

i would like to address at this point...
there in no point in trying to diagnose a defficiency without discerning the def/tox relationship as well... they are inseparable.

mace, despite the ph of magnesium sulphate being most soluble at 5-5.5 and then at 6.5 to 7.5 i would like you to think about the statement the ph chart etc and what it really means... (to add, can't disagree that you see less symptoms at 6 pH than lower values, especially if you are using pbp)
now on the other hand you said macro and you said magnesium and are correct on both accords. kudo's and much respect... not the total answer but yes it does have to do with macro's ie magnesium...

(joe),
... and with K.

since N and P (and S*) are mobile... (-) and K, Mg, Ca are not (+, ++)
we will eliminate the first two immediately N and P, anybody disagree?
now normally we have to consider S with MG as per MgSO4 but with pbp we don't.
we are also going to eliminate Ca, we know he used cal mag, and calcium always shows up immediately in the top growth of which we have no pics so we will eliminate it for that reason too.

so we are left with K, Mg and S.
of which we said all three...

now to the K/Mg deftox relationship. The brown spots are over K right away, vision taught me that years ago... but i would never say decrease the ammount of K in his regime, and besides he can't.

Potassium needs to carried to the site and left there when building plantys (immobile) and it needs to have magnesium there to build a proper cell wall. Magnesium is the same, even more so (++) and if not present duringn tissue building and K is then you get necrotic spot, no cell wall cell fails to hold water, deflated tissue goes BROWN and life goes on...

except that in nature/life/reality naturally airborne bacteria have developed for millenia to deal with this problem they ain't just going to sit in the primordial compost pile if you know what i mean, rot comes in many many forms and despite its wonderful effect to our planet is not that pleasant on the eyes espcially our plantys.

so to conclude S is also related, hey if pbp could use a sulphate mg which would cause it to be two part we wouldn't even be discussing this lol.
we know now that sulpher has always used as an antibacterial/fungal agent, the plant uses soluble sulphur within the cell wall to do the same thing.
not only can you see this by how quickly the spot went from brown to black but also if you understand the content of pbp, it is low on sulphur. no sulphates only fish meal and not much of it at that... anyways

1. remove the affected material
2. smoke a joint and think about this post.

a tip for mace, the ph solubility chart is just that a solubility chart, very mucklian in nature... when using the carbonate sources for soluble nutrients you would see a different spike on that graph indicating 6-7 being the best zone for magnesium solubility.

have a good day folks
peace.
pb

peace,

mace

 

[sproutco]

I don't think it is a magnesium problem like Mace is suggesting. Magnesium def would have yellowing between the veins on the bottom leaves. The veins tend to stay green.

Toxicity of potassium, if it even exists, would exhibit slender growth, longer internodes, and light green leaves. Later stages would develop a mosaic-like mottling followed by dull colored spots,leaf wilting and abscission. I don't think this is the problem either.

You did not mention how the plants are being grown. Soil? What is in it like dolomite lime? What is the ph? (Mace made a good point bringing up the solubility of nutrients.) Are you adjusting the ph of your fertillizer + water? You can check soil ph using the link in my signature. What nutrients does biogrow contain?

Bottom line, fertilizing at day 11 should be very weak.

 

[Gangabiss]

No I doubt it is magnesium deficiency. I've has that problem before and it showed up as yellowing on the veins and then brown spots like you said sproutco.

Yes the plants are being grown in soil with added perlite. It's a mixture of some soil I had left from a while ago and some seedling soil I bought for sprouting the seeds in.

There is no dolomite lime in that I know of.

I've never needed to adjust the ph of my soil before so I doubt it is that, but you never know. I don't have anything to test the ph with.

Bio-Grow is a basic organic fertiliser...I'm not sure on the ingredients. It doesn't say on the bottle.

The leaves are all a healthy green with no excessive darkness or shinyness that would usually accompany an overdose of nutes in my experience.

These rust patches seem to be showing up on the middle leaves on the plants. Not new leaves or the bottom ones. And only one or two leaves per plant.

Thanks for the help

 

[sproutco]

If there is no dolomite lime in your soil, then your fertilizer water should contain calcium and magnesium. Your fert label should give you ingredients or maybe check their website. Remember, plants need nitrogen, phosphorus, potassium, calcium, sulfur, magnesium, iron, manganese, zinc, copper, boron, molybdenum, and chlorine to grow. You can add calcium and magnesium to your ferts easily if needed by using 1/4 teaspoon(1.25ml) of both epsom salts and powdered gypsum per gallon (3.8L) of water. For super small seedlings, you might only need 1/8 teaspoon (.65ml) of each. As a bonus, if you use these two ingredients, you will supply the plants with sulfur.

Adding fertilizer water not ph adjusted is a recipe for disaster. You can get lucky if everything goes right but why chance it. You need to invest in a cheap ph meter. I think you will be quite surprised at some of the readings. If you get a meter that tests liquids, you can adjust your fert water and test soil ph. If your adjusting your fert water, I doubt testing the soil ph will end up being necessary. Don't grow blind!

Like I said before, feeding at the 11 day old stage is not necessarily wrong... it just has to be weak.

Hope this helps.

 

[Gangabiss]

Bio-Grow is a pretty commonly used nutrient so it should have all the main ingredients needed for healthy growth.

Could these patches be due to me not giving them enough fertiliser? They have really only started appearing since I stopped using the nutes when I noticed some slight tip burnage on the very lowest set of leaves. and then I started using plain water.
So really they have only had a very low dose of nutrients and they are now 16 days old from seed in a mixture of seedling soil, perlite and a small bit off All-Mix soil.

Should I risk it and try giving them a dose of half strength nutes next watering? I mean they should easily be able to handle it seeing as they are over 2 weeks old now and there are no additives in the soil. Right?

I never even considered buying a ph meter for growing in soil. I just didn't think it was needed...I've never needed one before. Maybe it would be worth it just for the peace of mind though.

 

[sproutco]

I can't give you a recomendation of how to use your fertilizer. I have no idea what 1/4 strength or 1/2 strength would be. I would suggest 100 parts per million nitrogen as part of your complete fertilizer. This numbers are useless I bet to you. So, better to error on too little ferts than too much. If your getting salt burn (tips of the leaves will burn) then "back off" the amount your giving them. If you are ever curious about how to be very exact in the way you use fertilizer, take a look at my thread in my signature how to make a nutrient solution from scratch. Feel free to ask any questions about that. Sorry I can't be of more help. Maybe check their (the ferts) website and see if they give suggestions for how to use their ferts or a feeding schedule. http://www.biobizz.nl/

 

[Gangabiss]

Well I've just ordered some soil so I'm thinking maybe I should just repot them as soon as I can to fix the problem...give them a fresh start.

The only leaf tips that have shown signs of burning are the very lowest single bladed leafs.
I'm not sure I want to make my own nutrients from scratch...no offence sproutco but I'd feel much safer sticking to my store bought nutes. I have used these before and had no problems.

It is not all of the plants that are showing these symptoms...only about 3 of them...could it just be that these plants are more sensitive to over/under ferting than the rest? There are a few that look really nice and healthy.

 

[sproutco]

http://www.biobizz.nl/ They have feeding schedules you can download. Take a look.

 

[Gangabiss]

Thanks for the link sproutco.

On that chart it says after the first week of vegging you can use 1/4 strength nutes. And I used 1/4 strength after 11 days so they should have been able to handle it right?

Does this mean that it could be from under ferting rather than over ferting?

 

[Gangabiss]

I'm going to be watering them tomorrow and I need to know wether to give them some more nutes or not.
Should I just give them plain water or give them some more nutrients? Then if it gets worse I'll know that it is underfeeding.
But I really don't want to have to do that to my plants...I find it hard to believ that such a small dose of organic ferts in such a weak soil mix could be causing this much damage to my leaves...which leads me to believe that it is proably from under ferting.

Unless anybody says otherwise I will probably be giving them some more Bio-Grow tomorrow at half strength...and if it does burn them then I'll just have to give them a flush.

 

[sproutco]

Green leaves on the bottom with burnt tips = too much fertilizer usually. According to the feeding schedule I saw it says to use 1ml per liter biogrow when using all mix and 2ml per liter when using light mix. So, use 1ml and see what happens. Better to underfeed.

 

[Gangabiss]

I did use 1ml per litre the first time. Full strength is 4 ml per litre.

The leaves on the bottom that look burnt are not all green. They are starting to go discoloured and yellowing from the edges...hmmm maybe they weren't burnt after all? Can that happen from underfeeding?

 

[Gangabiss]

Well I just watered my babies this morning with another 1/4 strength dose just to be safe...hopefully they won't get any worse.

I'm going to pick up some epsom salts for the next feeding also. Seems to be one thing the Bio-Bizz nutes are lacking.

 

[mace_ecam]

I don't think it is a magnesium problem like Mace is suggesting. Magnesium def would have yellowing between the veins on the bottom leaves. The veins tend to stay green.

sproutco, how many times have you withnessed this kind of def on a cannabis plant?
I had it a couple of times.
My fert did contain enough Mg, but i was giving too little nutes.
These patches always start out as shiney spots, then turn into necrotic patches.
If intervenal chlorosis appears under low Mg is depending on the growth stage of the cannabis plant and the levels of other nutes.
So far, only plantbuilder was able to give me an explonation of what exactly is happening.


Gangabiss,

the dead leafes on the bottom that you say are looking like overferted are just dying, overfert would show on the youngest leafes, too.
What you see there is assimilation, the plant get everything out that she can before getting rid of the leafe.
Mg is very important for cannabis, most "normal" nutes do not contain enough for cannabis, but don't overdo it with the E salts. Its a special cannabis thing with Mg

peace,
mace

 

[Xtbudda]

could it just be that these plants are more sensitive to over/under ferting than the rest? .

As you said, if your variables are all the same with the remaining plants, I usually chaulk it up to a finicky plant. I mean look at it, if others are doing well, then the others are sensitive or something is different within the soil, you cant see, ie: ph,mg,overwatering etc. for the affected plants.

I really think mg is a major player as I think some tap water is missing it and it needs to be added with epsom salts, etc. The problem I have found with mg missing is the plant overtime depletes what is in the soil and locks out other elements. Then we see this change and can take it for underfeeding, so we give it nutes which is overferting now, as it will be taken up because of the lack of mg in the soil locking everything.

My solution to this, whenever i run into it, is a clean water flush and repot into new soil. Then just water,epsom salts and hydrogen peroxide.

This might not be your fix, but i know my water sucks and needs to be left to bleed of chorline, as my water has chrolorimine in it. The problem with chrolorimine in your water, it retains chrlorine in the water.

 

[Guest]

Mate, BioGrow won't ever give you Mg def if PH is right. There's enough Mg especialy for 3 week old plants on veg.

 

[mace_ecam]

Mate, BioGrow won't ever give you Mg def if PH is right. There's enough Mg especialy for 3 week old plants on veg.

unless you're using too little

 

[Gangabiss]

Cool thanks for all the help guys.

So maybe I should have given them more than just 1/4 strength today?

I can't get any epsom salts until I go to my mates house which will be in a couple of days.

Should I bump my nutes up to half strength next watering (4 days)?

 

[sproutco]

If your going to add epsom salts to increase your magnesium, you should also increase your calcium along with it. Potassium, calcium, and magnesium all compete with each other getting into the plant. This is called cation competition or antagonism. The ratio of potassium to calcium to magnesium should be about 8:4:1 to 4:2:1 I don't think you are going to get stray necrotic spots from a lack of magnesium. Usually in most plants including mj, areas begin to yellow between the veins. In some plants these patches start in the center of the leaf. In mj, I believe it begins in the edges and works it way back. It takes a while with the leaf being almost 1/2 to completely yellow before necrotic spots may begin to form if at all. Check the ingredients in your fertilizer to see if calcium and magnesium is already included so you are not adding these in addition unnecessarily. Here is a picture of magnesium deficiency in mj:

You can see the yellowing between the veins. This is because magnesium is in the center of the chlorophyll molecule. This is what gives plants there green color. Magnesium is denoted as Mg. The lines are bonds between atoms. Unlettered areas are carbon.



IMO, I think the rust colored patches would be described as an excess of metals. Too much fertilizer concentrated in too small of a plant.