Yellowing of upper leaves, some sort of deficiency?

Currently at day 46 from the flip. Another 2-3 weeks to go for this strain.
Just wondering what is causing this? Been great all the way, and on day 42 I noticed this yellowing, there was none 3 days prior (except the usual down low stuff). I have started using cannazym as I will be re-using the soil, I have been using 2ml per 2.4l, so a rather low dose. Any ideas? Cheers

Looks more like nute burn than a deficiency issue. I also notice your leaves are shiny and fairly dark green, reinforcing my hypothesis.

Looks like K def.

3rd Monkey said:

Looks like K def.

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Yes I can also agree with that.

So I have been using the old PK 13 14 and have only just stopped using it last water, it has had the same amount of nutrients for about the past 2-3 weeks, no increase in strength. Could it be heat stress? Temps are high in the day, about 85-90. Thanks for the responses.

Bundykid said:

So I have been using the old PK 13 14 and have only just stopped using it last water, it has had the same amount of nutrients for about the past 2-3 weeks, no increase in strength. Could it be heat stress? Temps are high in the day, about 85-90. Thanks for the responses.

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You stopped using the PK, now it's deficient. You're in heavy flower and that's what they need most.

Heat stress will bring out any other minor deficiencies there may be lurking. That is not heat stress though.

Yeah right thanks. So stopping using pk will show a deficiency within a couple of days? Will it have detrimental effects if it continues? The girls are looking good, be a bugger to ruin them in the last few weeks! Thanks for the help.

Bundykid said:

Yeah right thanks. So stopping using pk will show a deficiency within a couple of days? Will it have detrimental effects if it continues? The girls are looking good, be a bugger to ruin them in the last few weeks! Thanks for the help.

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If you don't feed them, they'll continue to cannabalize. They are almost done going by the pics, so it's your call on if you want to feed.

If you have heat stress coupled with deficiencies, yea, it'll look bad quick. Any extra stress will make it show quicker and worse.

3rd Monkey said:

If you don't feed them, they'll continue to cannabalize. They are almost done going by the pics, so it's your call on if you want to feed.

If you have heat stress coupled with deficiencies, yea, it'll look bad quick. Any extra stress will make it show quicker and worse.

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Thanks man, I’ll battle away and see how they go.

3rd Monkey said:

You stopped using the PK, now it's deficient. You're in heavy flower and that's what they need most.

Heat stress will bring out any other minor deficiencies there may be lurking. That is not heat stress though.

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@Bundykid

Disagree! Strongly!

I say a pH related issue. The zyme is generally a limited spectrum that digest's cellulose from the roots. The plant sheds it like we do our skin. This increases some nutrient levels.....It also changes pH solution ratio's.

Also. Any elevated PK use by Canna or Hesi nutrient lines is stopped about this time.....

Not to mention that to have that much expressed in that amount of time says clearly that it's a pH based issue that is doing some blocking....The elevated PK use "masked" that issue.

Knowing what media your in will help greatly!

FYI,,,,,soil takes 5-7 days to show nutrient changes
Hydro in as little as 3-5...

That much showing in the plants, that fast, say it's not from dropping the PK! You have another issue coming into play, that's the culprit!

The plant is being "pushed" hard by the way the tips are showing burn. Typical for Canna and Hesi too... That is being right at the edge of "too much".
It also contributes to the ability of the pH to swing out too far.....

Did you have any period of time that you did not adjust pH in the feed or if in hydro/Coco,,,,not daily? When did you start the zyme in relation to the onset of this?

FYI: High amounts of K in bloom.....reduce THC production! Same for Mg..... N reduce's THC production but is more so if you have high N issues early.....

How big a light and how recent are the temps? Dark green in the middle with burn edges are also what light burn looks like. K deficiency in plants are rare. PH block or heat is more common issue. Also is symptoms are only show in at the top hots points in probably heat not nutes

Dr. Who said:

@Bundykid

Disagree! Strongly!

I say a pH related issue. The zyme is generally a limited spectrum that digest's cellulose from the roots. The plant sheds it like we do our skin. This increases some nutrient levels.....It also changes pH solution ratio's.

Also. Any elevated PK use by Canna or Hesi nutrient lines is stopped about this time.....

Not to mention that to have that much expressed in that amount of time says clearly that it's a pH based issue that is doing some blocking....The elevated PK use "masked" that issue.

Knowing what media your in will help greatly!

FYI,,,,,soil takes 5-7 days to show nutrient changes
Hydro in as little as 3-5...

That much showing in the plants, that fast, say it's not from dropping the PK! You have another issue coming into play, that's the culprit!

The plant is being "pushed" hard by the way the tips are showing burn. Typical for Canna and Hesi too... That is being right at the edge of "too much".
It also contributes to the ability of the pH to swing out too far.....

Did you have any period of time that you did not adjust pH in the feed or if in hydro/Coco,,,,not daily? When did you start the zyme in relation to the onset of this?

FYI: High amounts of K in bloom.....reduce THC production! Same for Mg..... N reduce's THC production but is more so if you have high N issues early.....

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Thanks for the reply, using soil and have never bothered with ph measuring or adjustments. The water here is as good as you can get. Never had any problems before. The onset of the yellowing started a few days after using the zym, first time I have ever used it. I have been using canna nutrients at or currently just below their recommended amount. 600w hps around 16 inches from the tops. Should probably check ph and see where is lays with my current mix. Would a good flush and start again with the nutrients be a good move?
Thanks for the response

ZeusBarks said:

How big a light and how recent are the temps? Dark green in the middle with burn edges are also what light burn looks like. K deficiency in plants are rare. PH block or heat is more common issue. Also is symptoms are only show in at the top hots points in probably heat not nutes

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Symptoms are showing at different heights, it may also be worth noting that one of the 4 doesn’t have any yellowing, this plant had a slow start but has kept up well, generally a bit small than the others. Currently looking the best. Temps have been an on going battle, need some sort of ac, generally they are around the 70, but it’s been hot here the past week and temps have been getting up to about 90.
Thanks

If it only shows on hot days I’d bet heat shock. Check ph it’s probably high. Plant raise ph as they eat nutes

Also this probably started showing when you cut nutes because nutes were making water acidic now without nutes water is too basic

Bundykid said:

Currently at day 46 from the flip. Another 2-3 weeks to go for this strain.
Just wondering what is causing this? Been great all the way, and on day 42 I noticed this yellowing, there was none 3 days prior (except the usual down low stuff). I have started using cannazym as I will be re-using the soil, I have been using 2ml per 2.4l, so a rather low dose. Any ideas? Cheers

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I would water till harvest, no nutes, they look prett much done, don't let sugar leavs go crispy

Bundykid said:

Thanks for the reply, using soil and have never bothered with ph measuring or adjustments. The water here is as good as you can get. Never had any problems before. The onset of the yellowing started a few days after using the zym, first time I have ever used it. I have been using canna nutrients at or currently just below their recommended amount. 600w hps around 16 inches from the tops. Should probably check ph and see where is lays with my current mix. Would a good flush and start again with the nutrients be a good move?
Thanks for the response

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When starting out AND at any time you add another supplement or additive to your feed mix. You should get a final solution pH. It's always good to know...

BACKGROUND INFORMATION:
Soil self pH's - (TO a point!)
In cannabis growing. Soil will settle in between about 6.4 to 7.0 as it's resting point pH. I use 6.5 as the point of record for me.
When you water. The soil will drop in pH by around a whole point or more. As the soil dries back out. The pH will rise back to that resting point.
This allows the nutrients to be up-taken at their diffing pH values of optimal availability.
This is how matures works...

If at any time you use a high or low pH that is over 8.0 or under 5.0, and you use this for any length of time. You can get a pH imbalance that blocks out certain nutrients. Left unchecked, this problem will kill the plant...
Keeping the soil to damp for extended periods will also bring on a pH issue...

For you, at this point....I would do a flush WITH a Ca/Mg and water pHed to 6.5 and water it at least once with the same.
THEN restart your nutrient use and be SURE to pH balance your solution to 6.7 (for bloom) and 6.5 (for veg).....IF the solution pH is over 1 whole point either way.....(YOU should be sure to pH this run every time you feed till done.)

I'll bet your solutions were marginal. At some point, something you added....tipped the scale and the pH swung out, blocking nutrients...
HIGH concentration solutions will play a role in keeping pH close to a problem.....
The zyme could have played a role too. By converting soil born nutrients to be too available to simply changing the solution pH to cause the soil pH to go over.

By pHing the solutions to "know" what they are. You will avoid problems down the road.

Be aware that seasonal changes in water pH is common (buffer ability too). Be sure to check every now and then to monitor that situation.

3rd Monkey said:

You stopped using the PK, now it's deficient.

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Not likely unless Base Nutrients has no P and K.

budman111 said:

Not likely unless Base Nutrients has no P and K.

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I will still have to politely disagree. 80-90 temps. High transpiration rate, late in flower, by the buds, etc.

Now I don't know what cannazyme is, so maybe that's got something to do with it like Doc says.

Bundykid said:

Currently at day 46 from the flip. Another 2-3 weeks to go for this strain.
Just wondering what is causing this? Been great all the way, and on day 42 I noticed this yellowing, there was none 3 days prior (except the usual down low stuff). I have started using cannazym as I will be re-using the soil, I have been using 2ml per 2.4l, so a rather low dose. Any ideas? Cheers

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Had the same issue a few years back, harvested 2 weeks later. Just kept watering no nutrients and did the best with temperature as possible. It was White Widow and excellent