Nute problem or she's getting old?

[Gramps]

Hi All,

Problem: Apical stem bud leaves developing brown spots, ok lower on plant

Medium/grow method: Promix HP

Feed and supplements used: Megacrop at recommended dose for lifestage, Calmag+ at 1ml per liter

water source: Tap water after 24 hour rest, 1000PPM after adding Nutes.

Strain/age: Northern Light Auto, at day 73

light used: Autocob

Climate: 75F - 20 hour day / 70F - 4 hour night

Additional info: Attached 3 pictures, 1st is top apical bud where the concern is, 2nd is a side branch bud, appears ok to me, 3rd is overall plant.

Any advice appreciated!

 

[namvet25]

Slight cal/mag def so make sure you still use it at every watering.She still is putting on bud weight so keep feeding bloom nutes.She may start showing a few yellowing leaves but this is normal when there close to harvest.

 

[Gramps]

Thanks @namvet25, good advice. I appreciate the quick response!

 

[Waira]

-- Hmmm, maybe not Ca mates,.. looks like Mn defc. to me,...

>>> How far away is that COB? about 18" is recommended,.. closer and it can cause stress issues....
1000ppm is pretty rich, you may also have a nute salt build-up issues, a cumulative thing,... how much of that is the water's base ppm? Hard water, high CaCO3 inputs can be a cause, driving pH up, load in ions, messing with uptake of nutes,...
....pH is suspect in there, though it's possible this is a simple lack-of type defc.,... but that in-pot pH is the info we really need, next steps hinge off that,... You'll need a decent spil pH probe for this, those cheapo skinny probe types you see around are crap, don't bother with them,... I have an Accurate 8 soil pH probe (Control Wizard Products) that's been gold for me ... but recently the price has jumped stupidly ... fact is, other companies sell the same unit under their name, better pricing (amazon it)-- it's all the same Chinese factory!
Meantime, get some distilled or RO water, and water the pot to get about a cup of run-off,.. take a pH and TDS reading... this won't give accurate in-pot pH, but if it's way off, that's still a clue we need,... ppm's will tell if things are just too loaded up in there, and a flush may be called for to reduce the load....

 

[Gramps]

Hey @Waira, thanks for the detailed response.

The Cob is 20 inches from the problem area. The base PPM of my water is 105 PPM and I'm adding 26 grams of Megacrop fertilizer to every 18 liters of feeding solution. That brings my total PPM in the feeding solution to 1040 PPM. I feed every watering which is happening once the top 3 inches of soil are dry, about every 2 days at this point in the plant's life.

My water base pH is 7.0 and the run-off water (without any nutrients added to the water) is 5.9 to 6.1.

I have 2 plants currently in the grow, the 2nd one is a Blueberry Auto at the same age and shows none of these signs. Both are in identical growing conditions.

I'll look into one of the Accurate 8 Ph meters, although I am using a Lab grade meter for water in and out of the pot. Not sure if probing the soil is going to give me a reading outside of between 6 and 7.

Thanks again brother.

 

[Waira]

- on the distance and water,....
--- run-off is a full point lower, so things are too acidic in there, likely related to the strong feeds,.... it's not a reliable indicator of actual in-pot pH, but it can provide a clue... check this "improved" run-off pH method here...

..... each pot is it's own little ecosystem mate, what happens in one does not reflect what;s happening in the other; too many pH influencing factors in play! Different strains, even pheno's can show variable tolerances and demands,....
pH probes are not "meters" though they get labeled as such- ... meters are for liquids only generally,.. more $$ pH probes may have a similar type electrode bulb type mechanism as a pH meter, but they to come with all the care and maintenance that ph meters have,.. all these are fairly fragile, let them dry out badly (no proper storage solution), store in low ppm water, don't calibrate often, and you risk ruining them permanently,...

this is the unit I refer too,...:smoking: ... shop around for "soil pH meter or probe" via google, and choices will pop up,...

 

[Gramps]

@Waira great info on the pH, I will hunt around for the meter you "refer' to.

Cheers,
G