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Re: Possible Deficiency ?
Andy Moore wrote:
> small brown spots over the leaves of my plants - these
> develop into larger holes and eventually destroy the leaves.
> more noticeable on my broader leaved plants.
>
> I use PMDD and tank parameters are roughly as follows:-
>
> PK 6.7-6.9, NO3 <10 mg/ltr, NO2 Nil, Fe circa 0.1, PO4 circa 0.015, GH 5, KH 3-4
> Gallonage is 50 UK Gallons - 2ml of PMDD added daily
I don't suspect a micronutrient shortage; if anything, perhaps a
toxicity symptom if you had too much of one micro nutrient. No further
evidence to indicate that however. You didn't mention the substrate so
I'll presume nothing there except gravel and possibly laterite or other
inorganic additives like clay, vermiculite, kitty litter. (no P in
those)
The macro nutrients which could cause the problem you describe if in
short supply are: potassium, nitrogen, phosphorus and magnesium.
Typically the older leaves tend to become yellowish before dying and
yellow spots precede the brown ones. Your PMDD dosing probably includes
enough N and K and Mg. Perhaps you have an acute shortage of phosphorus.
This might be the case if the problem plant is a fast grower like an
Hygrophila species. What are the plants which are showing symptoms or
growth patterns you don't like? Are there any curling of the leaf edges?
Also examine the new leaves for any deformation or yellowing. Those are
the other kinds of symptoms to watch for.
To test the theory, (I wouldn't add P to the water) I suggest doing one
of the following:
1) pot the plant in a mineral soil such as garden soil covered with
gravel
2) put a Jobe's plant stick broken into pieces around the roots of the
plant
3) make some clay balls with osmocote slow release fertilizer and put
them around the plant roots.
Steve