doesn't look like a major problem to me, might be a slight Zinc deficiency. about the only thing i know that turns leaf tips white.
Those tips look like normal tips to me and I see it on my plants all the time regardless of strain. An early indication of impending nute burn but without burned margins just below the burn line.
I've been having fairly serious problems with my CBD plants that have been in the same pots of soil/soilless for around 6 months and sadly neglected due to my health issues that have been corrected for the most part, (Leaky appendix for the last 5 years).
Finally got around to sussing out what the problem is and have concluded it's a zinc deficiency which is quite rare but with the length of time in the same media, low feed levels that I consider low on Zn in the first place and using Cervante's chart and grow bible hard copy with all it's clues can't find anything that matches the symptoms as close. Very similar to low manganese, Mn, but doesn't have the telltale green margins on the leaves. Newer leaves are developing interveinal chlorosis, small dark spots then dropping off. Flowers are not developing at all after 9 days of 12/12. Tips and margins are discolouring and burning and the youngest tips distorting. Older growth still healthy for the most part. (Note the tiny grow tip with buggered leaves center left).
All three plants have the same symptoms but the hemp one, my Otto#1 girl, is the worst with older growth getting into it now. This pic is her tonight and shows leaves with all the symptoms.
To treat the 3 plants I pulverized 2 - 50Mg tablets of Chelated Zinc Gluconate I take for my health, a B-100complex cap, selenium tab and half a tsp of Epsom salts with 4 drops of conc. sulfuric acid to drop the pH for 3L of RO water planning to give them a liter each. Being not sure of the toxicity level of Zn I diluted it to 4L and only gave them 500mls each. Should be enough to show some improvement in a couple days if I pegged it right. They needed water so soaked them down with more RO.
When I flipped the plants I gave them a good dose of some 3 year old Sensi Grow A&B, half dose each of Big Bud, Bud Factor X and Bud Ignitor along with a 1/4 dose each of Rhino Skin and Growtech CalMag. Pinch of Epsom Salts in 9L of water so they got 3L each and a bit of RO to wash the top free of nutes and soak the 4gal pots good.
I thought maybe that it was the Sensi gone bad that caused it but thinking back I saw these problems 3 months ago They were already touching the ceiling in the grow room then so strung a light chain across the front of them so they could lean on that while I was out of town for a month while the wife gave them enough water to keep them alive. Got to be 7ft tall plus a foot for the pot so I built a 4x4 lightly framed screen and have them bent over that pointing down about 45°.
I just went and checked my notes for my 7 week old veg plants from seed and waddaya know. Their last 2 feedings were Sensi and they look just fine. Drop that "maybe" to the bottom of the list.
I started using a different Super HPS made by Light EnerG to try it out and got thinking that maybe it was responsible for the lack of bud development so swapped out the new 1000W MH/HPS mag ballast and that bulb for my old 1000W MH mag and the 940W Hortilux conversion bulb that has proven it's worth on two previous grows. I doubt very much now that light is a factor but it's a great light so I'll let it run for the rest of this grow.
All this being said I sure don't see any sign of low Zn in the
@MJCanada 's plants. They look to have a little burn going on and I would suggest a 1 volume flush to reduce the amount of nutrients, especially N, this late in flower. More water if it's getting that close to harvest and let the plant salvage the nutes it need to finish from itself so the big fans start yellowing fast.
Sorry about the long story but this is the kind of process I go thru any time I run into plant problems whether it be my plants or some new grower's plants and they need help fixing what ails them. I was a big Hardy Boys fan as a kid and still have a big box with almost the whole collection from the early and mid sixties. My boys aren't readers so didn't want them. Get to relive some of that when I hunt for clues to fix plants I guess.
Have a Merry Xmas!
