Burnt edges...what causes this?

[huntsman]

I potted 40 toms three days ago, using 40% potting soil, 40% compost, 5% river sand and 5% (or less) perlite.

Could the compost be burning the plants??!

It shouldn't, because it's supposedly organic, but what else could it be?

Second question:

How do I combat the problem? I flushed heavily, but would appreciate your input, please...







Darn! I was hoping to take them to the Organic Market on the weekend too...

[bcday]

The dried-out leaf edges might only be windburn that occurred during the hardening-off process. If that's the problem, the new young leaves that are coming in will be fine as the plants become acclimated to their new situation.

[RayR]

Compost wouldn't have enough available Nitrogen to cause leaf burn.
Too much water (Poor drainage?)
Any chance of salt contamination?
There are a lot of possibilities.

[huntsman]

Thanks for the replies -

The plants had long since been hardened off in smaller containers, bcday, so if that's not the cause what might it be?

RarR - no chance of salt contamination on my side but who knows what happened at the composting plant, though they are reputable.

The only water they have had was a 5 hour soaking from below, though that WAS in a liquid feed solution. Perhaps that was too strong? It was a mix of poultry and seabird guano.

If that is the case, I can dilute in future, but what can I do now?

Help...?

[Heritage]

huntsman,

It does looks like fertilizer burn to me. Since you have already flushed them heavily, that is probably the best you can do for now. For seedlings I apply liquid fert @ 1/2 (or less) of the strength recommended on the label. But, it's probably not a good idea to let them sit in any fertilizer mixture for 5 hours, no matter how weak the solution.

Steve

[huntsman]

Hi Steve -

Yeah 5 hours does sound excessive, but it takes that long to water the grow bag from below...Perhaps I should just water from above, but with a more diluted solution...

I wonder if I should repot them all? Ton of work, but if I have to...

[RayR]

I agree with Steve, 5 hours is a long time for a soaking in anything!.
What is the NPK of the mix of poultry and seabird guano? If it's a high N mix and you didn't dilute it properly for a seedling in a pot, that definitely is the most likely cause of the leaf burn.

You could re-pot them in straight container mix and plain water and hopefully they will recover.
I wouldn't give them any additional fertilizer.

[Heritage]

Originally Posted by huntsman

Hi Steve -

Yeah 5 hours does sound excessive, but it takes that long to water the grow bag from below...Perhaps I should just water from above, but with a more diluted solution...

I wonder if I should repot them all? Ton of work, but if I have to...

Do you have any others seedlings so you could duplicate your procedure (with the same potting mix) but eliminate the fertilizer? Or try planting some new seedlings into the flushed potting mix. That might give some clues. If new seedlings aren't available, you might try re-potting a couple of 'burned' plants into fresh mix as a comparison and see how they look in about a week, compared to the ones in the current mix. It's kind of a guessing game/puzzle and I probably wouldn't bother transplanting all of the seedlings into fresh mix unless they continue to go downhill. Instead, I would eliminate all of the variables and try to find a definitive answer.

[Heritage]

oops... I cross-posted with Ray

[huntsman]

The NPK values aren't stated on the packaging, Ray - legislation is very lax out here, and yeah, I didn't take into account the fact that the seedlings might need a more diluted version.

Some good news is that we also used the liquid on some seedlings that I have yet to pot up and they are also burnt, so I think we have found the culprits...the liquid fert and me!

[Fusion_power]

That is typical salt/chemical burn. You can also induce similar symptoms by lowering the temperature which restricts phosphorus uptake by the roots. Either way, the nitrogen is out of balance.

The easiest way to resolve the problem is to leach the excess nitrate out of the potting mix by flushing with water. Once you have them flushed, very very carefully re-add a low dose of nutrients to get the plants back growing.

DarJones

[RayR]

Originally Posted by huntsman

The NPK values aren't stated on the packaging, Ray - legislation is very lax out here, and yeah, I didn't take into account the fact that the seedlings might need a more diluted version.

The heck with legislation, it just seems like common sense that a company producing a fertilizer product would want you to know what you are getting in NPK value at least and give you the proper application rates. As far as organic fertilizers go, depending on the source bird guano's can be some of the strongest sources of Nitrogen and Phosphorous out there and if they are produced from fresher deposits of droppings, they typically have a very high available N content.

[huntsman]

Heh heh!

I hear you Ray, but in the absence of local info, common sense tells me to look further afield, hence my quest here. Lucky me, eh?

So what do you recommend to treat this issue, now that we have established what the cause is?

[dice]

I have seen that on larger plants that I fertilized on a hot day with liquid
fertilizer that only contained phosphate and muriate of potash, too (no
nitrogen). I followed directions and diluted it at 1 tablespoon per gallon
of water. I suspect that the chlorine in the muriate of potash was the
culprit in my case, but leaf margin necrosis can be caused by a variety
of nutrient imbalances. Bird guanos can be pretty hot (high in ammonia
compounds) if not composted for a few months before use.

You can still use it, but it apparently needs to be diluted more than
whatever dilution you used last time.

[huntsman]

Hiya dice!

Yeah, I've dropped to 66% of what I used previously for the peppers I have been potting this morning, and will drop to 50% when I next do toms, as they are clearly more susceptible to burn via this particular fertiliser.

I have no way of knowing how long the guano has been composted, but as it's late Spring now, they are probably selling it very quickly, and thus not leaving it very long at all...