Phosphourous deficiency?

[psifactor]

Hey guys,

 

I'm looking for some advice as to how to treat this plant.

I've done a bit of research, and I'm fairly certain that the problem is phosphorous deficiency.

 

No idea what the strain is, plant is about 2 weeks old, using 250W MH in growtent with exhaust fan and pedestal fan for circulation.

 

This is strange however, given the soil claims to contain "controlled release fertilizers" (Yates premium potting mix). The plant seems to have slowly gone yellowish and has a rather large deep purple blotch on one of the leaves.

 

I've fed it some ferts (Miracle-gro 15-13-12) to try and bring the phosphorous levels back up, and I'll test the soil pH asap.

 

Any ideas what i should do? I'm worried about giving it the extra fertilizer, considering it might burn the plant from the already present "slow release fertilizer", I've attached a few photos of the troubled seedling.

 

On a side note: the cotyledons are going a pale white colour and shriveling up, is this normal? or perhaps a symptom from the deficiency?

 

Cheers!

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[Luke Skywalker]

Most of the slow release ferts are temperature dependent, with higher levels released at higher temps.

 

I would suggest overwatering as a more likely culprit. Don't water again until the surface few mm are dry. You'll start to get a feel for watering requirements by lifting the pot and feeling the weight. As it dries out it will get lighter.

 

Cotyledons are more like an initial energy source for the plant than anything else. These should naturally wither and die as the plant starts developing true leaves and they start producing food for the plant through photosynthesis.

 

Don't overdo it on nutrients, 1/4 strength of something like miracle grow is more than enough, and even then in soil you will have plenty of nutrition for a few weeks at least.

 

Give it time, don't water until you really need to, and get a soil pH test kit soon. Good luck and I hope that helps somewhat. Btw most nutrient deficiencies are caused by pH rather than actual deficiency of the nutrient(s) in question. Overwatering can show as a deficiency like symptom too, as the plant has often lost a substantial par of the root system responsible for providing nutrient for itself.

 

Good luck and don't worry too much, you'll get he hang of it soon enough. My best advice is patience and don't overanalyze such issues.

[psifactor]

Thanks for the assist

 

I'll leave it for a while and see how it goes. I guess i have been watering it quite a bit, so I'll let the surface and a bit dry out and try to cut back on the watering (agonizing to do XD)

 

Note: Also, it might be helpful to list the temp / humidity. Thermometer in the tent reports 26 degrees celcius, and 43% humidity. Lights are on 24/7.

Edited September 1, 2010 by psifactor

[psifactor]

Wierd necrotic patch has almost doubled in size over night, but i think the purple on the stem is slowly returning to green (bottom up). Should i remove the dieing leaf? or keep it as an indicator to see if the problem is progressing?

[psifactor]

Sorry about the now triple post haha, I guess I'm stressing out a bit over this problem.

 

I've taken some more photo's of the plant, it's quite wilted and the leaves have become quite yellowish, as well as the spreading necrotic spot on the leaf. For contrast, I've also included a picture of it's healthier sibling (apart from a bit of burn which has slowly been recovering).

 

What do you guys think is the best course of action for this plant? I really want to save this little seedling.

 

Thanks

[Olly]

Giddday.

 

What's the Ph reading?

 

Certain nutrients are only available at certain Ph levels so she may have a phosphorous deficiency but not because it's not in the soil but because the incorrect Ph is locking it out.

 

My 2c...

measure the Ph of your soil so you know where you stand & adjust accordingly.

 

worse comes to worst start over & repot in a good grade potting mix. Just do it carefully.

 

Best of luck with it.

 

Olly

[psifactor]

Got a pH test done today, looks to be around 6.5-6ish, slightly acidic. Overnight that pesky necrosis has almost spread across the entire leaf.

 

I'm thinking, increase the pH around .2? What do you guys think?

 

EDIT: also, just tested the healthier plant, which seems to be around 6.

 

Thanks,

Edited September 3, 2010 by psifactor

[potrocket]

Gday mate . I'd recommend using 100% organic soil with no slow realease ferts in it ! What soil are you using ? I'm guessing that you are in the US ?? if you are using fox farms OF i hear its to hot and needs to be mixed with some light warrior ! But shes overwatered for sure as LS has said ..this causes the plant to be fed more if your soil is not organic ! All the best mate ! And the ph is fine around 6.5 ! I keep mine around 6.8 during flowering to allow for optimal calcium uptake ! Edited September 3, 2010 by hazedaze

[psifactor]

Not US, all Aussie Using "Yates Premium Potting Mix" which my other plant seems to love, but this one obviously hates it.

I'll concentrate on that over-watering problem, and see how it fares.

 

On a side note, there's these strange little pesky fly type things, not sure if they are fruit flies or what, but I've seen them on the soil a few times, as well as a small black borehole type thing on the leaf of the upset plant.

 

Anyone know any good organic ways to keep these little flies out? And / Or what may have caused that hole in the leaf.?

 

But thanks for all the help, it's been much appreciated =D

[potrocket]

Ahh oky The ole yates premo ? .. I used a bit during winter mate and it came with fruit flys crawling all over my soil as well ! I have a mate in sydney who had the same problem as well ! My thoughts on it are that it needs to be rested in the sun and rain for a few weeks because it does have slow realease ferts in it . Some would even go as far as picking the slow realease ferts out of it and then letting it sit outdoors for a while . try google (nicks mix soil) see if its near you i hear this soil is pretty good but not for me as i live outta reach to get it ! All the best ! Edited September 3, 2010 by hazedaze