Help! Rust fungus or lack of Mg/Ca??

[HempKat]

How do i solve the problem? adding dolomite should be enough? or do i need some specific Ca:Mg ratio? yesterday i stopped watering and tomorrow i'll check the soil if its dry so the plants can intake the minerals when i water. I will test pH tomorrow, which range should i expect?

Dolomite lime is a good preventive measure but it's not a cure all and over time it will become depleted but that's definitely a good amendment for your soil mix, not only does it help to maintain a good ph but it also is a source for calcium and magnesium. You're essentially growing in a custom soil mix and the ideal ph value for soil is 6.5 but anything between 6.3 and 6.8 is generally considered good although you do want to try to keep it at the 6.5 sweet spot. If you're ph is coming in between 6.3 and 6.8 it probably is not a ph issue.

 

[exploziv]

@HempKat you say dolomite lime is good to mantain a good ph but i guess it depends on the soilmix? it raises the ph from what I know, so you gotta account for that.

 

[HempKat]

@HempKat you say dolomite lime is good to mantain a good ph but i guess it depends on the soilmix? it raises the ph from what I know, so you gotta account for that.

Yeah I'm sure the composition of the mix is a factor although I don't know exactly how much as I always used just regular potting soil. I also never tested for the effect on ph of just the dolomite by itself. When I first started I saw lots of people advocating the use of dolomite lime in soil at the rate of 2-3 tablespoons per gallon of soil as a way of buffering the ph and providing a source of calcium and magnesium which tends to be deficient in lots of the fertilizers cannabis growers use. So based on all that I made it a habit from the beginning to add dolomite lime along with extra perlite and vermiculite to my soil and things always seemed to work well for me. Although there are fertilizers out there that still require adjusting the ph up or down even with dolomite lime in the soil but I would estimate that 90% of the fertilizers I ever used required next to no adjustment of the ph value when also using dolomite lime. Now how much of that was due to my water source, the dolomite lime or the fertilizers I used I couldn't really say for sure.

 

[stiff]

Not to forget that cannabis eats calcium. Its like a tomatoe plant,they live of it...and they want a lot of it. You could almost call it part of their diet.

 

[Three Berries]

I use to add pea gravel, then went to some 'soluble' limestone that was actually pulverized and pelletized. But quit using that too. I could not have made more errors.

 

[Creeperpark]

Last words on this thread, it's from too much calcium!
https://pevgrow.com/blog/en/lack-or-excess-calcium-in-the-marijuana-plant/

 

[Three Berries]

And from that article this is exactly what I see.

A calcium deficiency is much more noticeable than toxicity. A calcium deficiency will always begin in new growth and the top half of the cannabis plant. The reason for this is because of calciums immobility, and this means it won’t travel to older leaf growth. So, a clear indicator of spotting a calcium deficiency is by evaluating what portion of your plant is being affected.

Visual indicators are light yellow and brown spots that look similar to rust. These spots will generally start near the edge of the leaves or near the veins. As the deficiency expands, these mottled colors will begin to envelop the entire leaf. New leaves will usually curl, and the topmost area of growth will slow down in vigor.

If I see a new leaf tip with a hint of yellow and if I do not add the CaCl2 as I have been doing; then the leaf will slowly yellow between the veins and get the dead rust spots. I can see the new transplants yellowing between the veins as the roots haven't spread out to where I'm adding the top dressing (edge of bucket).

On my veg tent it has a green tinted window that highlights this yellowing. When looking at it under the straight LED it's harder to see.

I have this type leaf on my oldest flowering one now from when it was in veg.

Here's a better pic from today. The one on the right is 3.5 weeks into flower an the other is 1.5. It's really stretching now. Both got some Ca yesterday but not today. You can see the yellow tips and some off the other leaves that it advanced because I was not doing enough Ca.

And even the old dried up leaves on the bottom are tough to pull off.

CO2 today in the veg tent is around 2000ppm. This will be dropping this week as the heater is going to be shut off. So the Ca needs should drop from the current use. Still the CO2 will be above 1000ppm I think as it seems to accumulate in the veg tent, being higher inside that in the rom usually.

 

[Three Berries]

BTW Amazon has powdered CaCl2 in 2lb packages for $13 right now.

 

[f-e]

I can't imagine it being excessive calcium, if calcium fixes it. Though their is an explanation surrounding excess calcium limiting uptake. Like getting coke or a straw, or milkshake, or ice cream.

1200ppm still has me scratching my head. I expected it to be powder but see it measured in ml. I quite fancied double checking the ppm in solution, but as it's watered down in a bottle, I don't have the figures.

 

[Three Berries]

The liquid I'm using (Bonide Rot-Stop) is 9.2% Ca. I use rain water to make my concentrate. I upped it too to 1700-2000 ppm. Ordered some powder anhydrous today.

I have some MgCl2 powder but don't use it due to the little bit (10%) in the well water and the langbeinite I add to the soil.

Last year with that yellow plant I thought it was K and Mg issues and was feeding it a liquid langbeinite concentrate as I am currently with the CaCl2. It did nothing.

This will be an interesting grow and looking to be my best ever. I need to get in and trim the insides out of them again.

 

[f-e]

So you are putting that whole pint in 6 or 7 gallons?

 

[Three Berries]

So you are putting that whole pint in 6 or 7 gallons?

Whatever it takes to get to the PPM target. But I'm about out of this stuff. No sense paying for a liquid when if you just leave it open to the air it will turn into the same.

 

[f-e]

We get a version about 77% that resists taking on water a bit better.
I will put it in water myself, to make a known solution I can dose. If you choose to let it suck up water itself, that will mean weighing it before and after, and accepting that result won't be particularly stable. I would rather saturate it on day one. You could put something like 200g in 400ml to make that rot-stop. I would think some Mg and Fe would be wise to. They are typically combined with Ca additives, so as to stay available

 

[Three Berries]

I'll just mix to the ppm I want. i'm not picky. I add some epsom salt for the flower nutes but there is plenty in the soil already and a bit in the water.


Langbeinite

 

[TanzanianMagic]

View attachment 18123719

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There is likely a big problem at the root system.

What is the run-off - EC/PPM, and pH?

"Using a mix of soil, compost, peat and vermiculite. Using the Top Crop set for fertilizing (brand from Spain)."

This is way too complicated. You should be using a brand dedicated to growing cannabis. Top Crop sounds good. However it is highly likely that their nutrients were tested and designed to go with their own substrate.

Also I would either go with a simple medium like coco.

Or go all the way and make a supersoil, complete with organic nutrients that contain N, P, K, Ca, Mg, S, Si, micronutrients. Organic nutrients are almost always contained in something else (leaves and fruits, manure, rocks) and need time and sugar to decompose and become available.

Also...

"I have a 60 liter tank for automatic water. Tap water is ok here, drinkable from the tap. Besides i add dechlorinating for fish. Should i use those concentration of calcium and magnesium in the 60 l tank or water the plants once a week or two manually with those ammounts?"

Don't add any dechlorination, just let it stand next to the plants for a day or more. Or use R/O filtered water, with himalayan salt and cal/mag added back in (only enough to replace the cal/mg lost by filtering).

 

[Three Berries]

The flowering plants are slowing down on the Ca needs a indicated by yellow new tips. The second one is about done with the stretch at 3 weeks. First is almost 4 weeks in flower.

The two veg plants I repotted and they took a hit, being really slow to recover. It's been a week and I finally watered them with some full strength nutes along with the Ca when needed.

The last transplant I wetted the soil enough that I could pack it and make and indentation the same size as what was going in. This time I wanted the soil dryer and looser. It made for a rough transplant. But the bigger of the two finally took off so much I though it went into flower looking from the outside this morning.

Temps are heating up so I'm loosing the high CO2. And the flower tent is getting too hot at 85F, as if I use temp for the fan control the humidity nosedives. So the mister humidifier is on low forcing it to cycle yet maintain a good VPD.

 

[King's Indican]

why do you add himalayan salt isnt it mostly sodium chloride?
@TanzanianMagic

 

[TanzanianMagic]

why do you add himalayan salt isnt it mostly sodium chloride?
@TanzanianMagic

Agreed, and most people should be using some other way to add micronutrients like seaweed or lavameal, however very small quantities, rarely, can be beneficial by adding extra minerals.

The thing is this - ordinary table salt is Sodium and Chloride - and nothing else. Which means the positively charged sodium and negatively charged chloride are only attached to eachother - you release one, you release the other. However seasalt and Himalayan salt have many different micronutrients that are also negatively charged, and as such connect to the sodium. In seasalt, positively charged sodium can be linked to and therefore release negatively charged phosphate, bromide, sulfide, fluoride, oxide, nitride, iodide, etc.

Again, you're right about the sodium and the chloride, so use this rarely if at all.

More on using fermented seawater, also high in sodium and chloride, as a fertilizer, why, and dilution ratios:

https://ilcasia.wordpress.com/wp-content/uploads/2012/02/chos-global-natural-farming-sarra.pdf

Cho's Global
Natural Farming
by Rohini Reddy

CHAPTER - 3 - N NATURAL FARMING INPUTS

SEAWATER AND FERMENTED SEAWATER (SW) The deeper the sea water is the higher the salt content. There fore it is desirable to use the surface seawater. Organic matter in sea water produces an excellent effect when the microbes of land and the minerals and microbes of seawater meet. Brackish provides a favorable conditions for microbes. Which in turn helps support may plankton and many fish that eat the plankton. In other words fermented seawater provides abundant energy to the crops and the livestock. Because of viruses skin disease occurs. When skin looses fat, the number of microbes decrease and even such a small change can induce out breaks of disease. Sea water can solve this problem. Adding rice-washed water (5ml) brings out its best properties. Rice-washed water and f e r m e n t e d p l a n t j u i c e ( 5 m l) t o s e a w a t e r (diluted 30 ml to one lit water) brings out its best properties. Rice washed water has an effect like that of yeast. It is more effective when oriental herbal nutrient is mixed. The combination has a similar effect when the river and sea merging point where freshwater and seawater meet. It provides a favorable condition for microbes which in turn support many plankton and many fish that eat the plankton. In other wards fermented seawater provides abundant energy to the crops and the live stock. When the microbes of land and the minerals and microbes of seawater are combined it produces an excellent effect for crops and livestock. 6

HOW TO PREPARE SEA WATER. For storage, pour seawater in a large bowl and leave it for a day to let air borne microbes go in it. 1. Using Seawater (SW) as an NF Input While Natural Farming uses materials that farmers can prepare by themselves, other natural inputs need to be collected away from the farms. Such inputs include seawater (SW) and natural minerals (NM). Seawater and sun-dried salt are two sources of nutrients and minerals regarded by Natural Farming as also essential together with NPK. WHEN AND HOWTO USE SEAWATER One lit Seawater is diluted with 30 lit water, while sun-dried salt is diluted 2ml for1000 ml water.
1. To sweeten fruits. WS-Ca is added to diluted seawater and then the solution is sprayed twice in one month and then 20 days before harvest. 2. Soil application. Sun-dried salt is applied to soil at 5 kg for every 10 acres. 3. Prevent feather loss in chickens. To avoid feather loss of chickens in summer, BRV (200) and WS-Ca (500) is mixed with diluted seawater and fed to chickens once in two days.

Testimonial:

Sea Salt makes a MAJOR difference in your plants!


"This is another example, where a little bit goes a long ways. If we have too much, it is actually a toxin. But in the right amount, in the right proportions, it's just incredible what it does."

Sodium in plants: perception, signalling, and regulation of sodium fluxes
Frans J. M. Maathuis
Journal of Experimental Botany, Volume 65, Issue 3, March 2014, Pages 849–858,
Published: 22 October 2013

Although not essential for most plants, sodium (Na+) can be beneficial to plants in many conditions, particularly when potassium (K+) is deficient. As such it can be regarded a ‘non-essential’ or ‘functional’ nutrient. By contrast, the many salinized areas around the globe force plants to deal with toxicity from high levels of Na+ in the environment and within tissues.