Blackberry week 4 flower, losing leafs fast!

[Hydrogrown]

Hey guys and gals, I need your help. I have two blackberry plants in flower, have been losing leafs steadily since the begining of flower, but I can't seem to pinpoint the problem. This started with the lower fan leaves and is spreading slowly to the top, although the canopy is mostly unaafected by any symptoms.
Symptoms
Curling and twisting of the fan leafs themselves
drooping of the sugar leafs near the buds
burnt looking margins on fan leafs
black spots/ streaks near the tips
yellowing, and once this occurs the leafs fall of from the force of my fan.

I have been pulling off the ones that are very pale yellow because they fall off so easy anyway, and I can't see behind the plant so I'm trying to get them before they fall out of sight. Here are the leafs that just came off, and then a picture of the plants now

Most leafs look like this before they fall off\/

and the ones that stay on look like the two above

Ph is always kept near 5.5-5.8, ppm are around 1200 now, rh is 80% high, 30-40% low with lights on. Have some heat issues too, daytime is 84-86 and occasionally jumps to 90-91. Night time is right around 68-70.
using bc boost, bloom, awesome blossoms, silica, and h202. I was using super thrive but stopped after I heard it can promote leafy nugs.
I am willing to try anything to get these girls to harvest. Oh yes! I had to trim the roots after a male was taken out of the dwc setup about 2 weeks ago, I might have burned them a bit after that but the nute have been brought down since then and the girls are drinking steady about 1 or 2 gal a day. I also just switched to R.O. water this week. Any help is appreciated, I am really bummed out by how they are doing, I've been pretty meticulous in my care with them and it seems like it was all a waste. Peace and thanks for looking

 

[Mr. Krip]

Did this start when you switched to the R/O water? It looks like it may be a K deficiency:

Leaves are browning or yellowing. Yellow, brown, or necrotic (dead) patches, especially around the edges of the leaf, which may be curled. Plant may be too tall. >> Potassium (K) deficiency

It also looks like it MAY be due to overfertilization.

Also, what type and how close are the lights?

BTW...you should NOT use SuperThrive in flower.

 

[Mr. Krip]

Here's some more info on a possible K deficiency:

Potassium (K) Mobile Element and Macro Element

Potassium plays a big role as well. Having good amounts of potassium in your plants helps in having sturdy and thick stems, disease-resistance, water respiration, as well aids in photosynthesis. Potassium is also found in the whole plant. It is necessary for all activities having to do with water transportation. Potassium is necessary for all stages of growth, especially important in the development of Buds.

Having to little of Potassium in your plants causes the plants leaves to show retarded growth and show a scorched tip and edges around the leaves. Plants may stretch and your branches can be easily broken or weak. Don’t get this deficiency confused with iron, because it almost acts like iron but to tell the difference in the two is: for potassium the tips of the leaves curl and the edges burn and die. Older leaves may show a red colour and leaves could curl upwards. Dead patches (Necrosis) can happen on the margins of larger fan leaves thus, the leaves will eventually die off and turn brown. The Older leaves will show different patches of colour (mottle) and turn yellow between the veins, following by whole leaves that turn dark yellow and die. The plants overall growth slows down, mostly when they are in vegetative stage. To little amount of potassium also slows the growth of buds during flowering stages. Dark edges will appear around the edges of the leaf when the deficiency is starting to happen. When your Relative humidity is low, you can almost bet your going to soon get a potassium deficiency from your plants perspiration.
Potassium can get poorly absorbed when having too much Calcium or ammonium nitrogen, and maybe cold weather. Having to much sodium (Na) causes potassium to be displaced. SO keep those in mind… Parts affected by a Potassium Deficiency are: older leaves and leaf margins.

When you have too much Potassium in your soil, it can lead to big troubles, like salt damage and acid fixation of the root system, as well as too much potassium can cause a calcium deficiency. Your fan leaves will show like a light to a dark yellow to whitish colour in between the veins. Due to a molecular imbalance, potassium toxicity can cause a reduced uptake and lead to the deficiencies of Mg, and in some cases, Ca. Also leads to the other nutrients to not be absorbed properly leading to lots of other deficiency such as: magnesium, manganese, zinc and iron and can cause problems with calcium as well.

Problems with Potassium being locked out by PH troubles
Soils with excessive Leeching and High ph soils and or water.Soils that are potassium fixated. An excess of kitchen salts (sodium) in the root system/environment.

Soil

Potassium gets locked out of soil growing at ph levels of 4.0-5.5
Potassium is absorbed best in soil at a ph level of 6.0-9.5. (Wouldn’t recommend having a ph of over 7.0 in soil) anything out of the ranges listed will contribute to a Potassium deficiency.

Hydro and Soil less Mediums

Potassium gets locked out of Hydro and Soil less Mediums at ph levels of 4.0-4.5, 6.0-6.5.
Potassium is absorbed best in Hydro and Soil less Mediums at ph levels of 4.7-5.3, 6.7-8.5. (Wouldn’t recommend having a ph over 6.5 in hydro and soil less mediums.) Best range for hydro and soil less mediums is 5.0 to 6.0. Anything out of the ranges listed will contribute to a potassium deficiency.

Solution to fixing a Potassium deficiency
Any Chemical/Organic nutrients that have potassium in them will fix a potassium deficiency. Again Peters All Purpose plant food 20-20-20, will cure the potassium deficiency , Miracle grow Tomato plant food, Miracle grow All purpose plant food.( Only mixing at ½ strength when using chemical nutrients, or it will cause nutrient burn!) Some other supplements of potassium are: Wood ashes, which are fast absorption, Kelp Meal, which is medium absorption, Greensand, which is slow absorption, granite dust, which is slow absorption. Sulfate of Potash, Sulfate of Potash Magnesia, Muriate of Potash, which are medium absorption. FOXFARM GROW BIG HYDROPONIC CONCENTRATE, which is fast absorption. (FFGB can bring your ph down as well) Earth Juice Meta-K, which is fast acting. (Can bring down your ph as well) Leaves will never recover, but the plant will show recovery after about 4 to 5 days when using a fast acting nutrient.

Note: Wood Ashes, can make your ph go up a bit, so please monitor your ph when using it.
Now if you added to much chemical nutrients and or organics, (which is hard to burn your plants when using organics) you need to flush the soil with plain water. You need to use 2 times as much water as the size of the pot, for example: If you have a 5 gallon pot and need to flush it, you need to use 10 gallons of water to rinse out the soil good enough to get rid of excessive nutrients.

 

[HashAssassin]

Nute burn and lockout. You need to flush out your plants. Empty the res, scrub it clean, and refill with plain water. Adjust the pH of the water to 5.8 and run your system for 24 hours. Do that every time you do a res change and you should be fine.

 

[Hydrogrown]

I came to the same conclusion last night with that problem solver, but I have been using plenty of K; bc boost is 7%, awesome Bl -11%, Silica-.5%, and bc bloom is like 5% =/ It started before R.O. water was added so I don't think that is doing it, and I added the superthrive to see if it would help the problem early on maybe 2 weeks ago, I am definently done adding it now idk what I was thinking, gotta save it for the grow cycle.

Still then, my ph is 5.4 now after topping up on water only, and I usually keep it at 5.5, but won't readjust it until it goes over 5.8. I'm switching between 250w hps w/ superlumens and 400w w/o the sl to try and get heat down, today with the 400w it was at 90F (FML!) I seriously need to fix this because I'm sure it has a lot to do with any problems occuring. The K definition is spot on though man. It may be overfert but these are week 4 flowering plants at 1100 ppm, I've seen people here using like 1800 ppm by now, am I wrong? Maybe my plants are sensitive because they were underferted a couple times in veg, idk. Thanks so much for your help Krip, you are a great guy. For now I'm gonna mix some fresh nutes with plenty of K at the right ph and work on my temperature problems. I don't wanna drop the light to 250w w/o superlumens cause they have been getting the 400w the whole time, and of course my yeild will suffer, but I might make the switch soon, I mean better to harvest than melt my plants while I'm gone or worse


Still taking any suggestions though!

 

[Mr. Krip]

Take Hash's advice! Even if you have K in your nutes, if there's lockout, the plant may not be able to uptake it.

 

[Hydrogrown]

A hydro flush? I've never heard of that or I would've done it sooner! Hash is the reason I my plants are still alive right now, thank you a MILLION times