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Bronze patches?
- Thread starter happd
- Start date
It's hard to tell just from the picture. aridbud's suggestion, bud rot is possible. The bronze color is similar. Heat burn, light burn, or windburn are all possibilities. Genetics, mutations, are possible but unlikely, I see a burnt brown leaf tip a bit lower. Which means it's probably not variagation. Nutrient burn or PH are possibilities.
You need to narrow it down. What part of the plants are burning? Just the tops closest to the lights? The entire plants, the shady parts, or the parts furthest from the lights? You're growing indoors which makes bud rot much less likely. What's your humidity? Is it sticky hot or dry hot? I notice the bronzing is on the leaves and tips not in the flowers themselves. Bud rot starts inside the flowers and then spreads to the leaves and tips. Check inside a flower or two. You describe them as not being brittle or dry, this is also typical of mold. Mold almost feels damp.
Are the plants burning only at the tops closest to the lights? Hold your hand where the buds are for 30 seconds. How hot does it get? Do you have a fan blowing all the time? Is it blowing on the plants or on the light? Always aim your fan at the lights and air between the plants and the light. Never at the plants themselves. This will eliminate light burn and wind burn. It's the hottest part of summer and plants get overheated. This is my guess, the lights are hot, maybe you don't have enough air circulation, and the tops are getting into the high 90s and above.
Nutrient burn is also possible. Are you feeding them lots of chemical phosphate fertilizer? The color reminds me of nutrient burn. As you get closer to harvest the plant needs less nutrients. A lot depends on if you're using hydro and soil. The nutrients circulate through soil much slower. Growing hydro it's easy to burn your plants or develop PH problems.
You need to narrow it down. What part of the plants are burning? Just the tops closest to the lights? The entire plants, the shady parts, or the parts furthest from the lights? You're growing indoors which makes bud rot much less likely. What's your humidity? Is it sticky hot or dry hot? I notice the bronzing is on the leaves and tips not in the flowers themselves. Bud rot starts inside the flowers and then spreads to the leaves and tips. Check inside a flower or two. You describe them as not being brittle or dry, this is also typical of mold. Mold almost feels damp.
Are the plants burning only at the tops closest to the lights? Hold your hand where the buds are for 30 seconds. How hot does it get? Do you have a fan blowing all the time? Is it blowing on the plants or on the light? Always aim your fan at the lights and air between the plants and the light. Never at the plants themselves. This will eliminate light burn and wind burn. It's the hottest part of summer and plants get overheated. This is my guess, the lights are hot, maybe you don't have enough air circulation, and the tops are getting into the high 90s and above.
Nutrient burn is also possible. Are you feeding them lots of chemical phosphate fertilizer? The color reminds me of nutrient burn. As you get closer to harvest the plant needs less nutrients. A lot depends on if you're using hydro and soil. The nutrients circulate through soil much slower. Growing hydro it's easy to burn your plants or develop PH problems.
Thanks for the thoughtful responses and I should have given more info.
I will give proper temp and humidity when lights on tomorrow but believe humidity is low 40s with temps low 20sc.
4x2 tent with 6inch exhaust fan and 2 clip on fans moving air. 320w qb sitting about 20 inch above plants. Light doesn't feel warm at top of plants. Running dwc and just flushed. Before flush was arou d 800ppm and 5.9 pH. Running gh 3 part with no boosters.
They do seem to be only burning in the upper portion of plant and mostly to one side where the fan was blowing directly on plant. Tip burn is very recent and not throughout entire plant. When I touch the spots it doesn't wipe or leave residue on my finger.
Strain is Skywalker og and unfortunately I lost file of when turned to flower. I'm guessing another 3 weeks to go as pic is of a less mature bud.
I will give proper temp and humidity when lights on tomorrow but believe humidity is low 40s with temps low 20sc.
4x2 tent with 6inch exhaust fan and 2 clip on fans moving air. 320w qb sitting about 20 inch above plants. Light doesn't feel warm at top of plants. Running dwc and just flushed. Before flush was arou d 800ppm and 5.9 pH. Running gh 3 part with no boosters.
They do seem to be only burning in the upper portion of plant and mostly to one side where the fan was blowing directly on plant. Tip burn is very recent and not throughout entire plant. When I touch the spots it doesn't wipe or leave residue on my finger.
Strain is Skywalker og and unfortunately I lost file of when turned to flower. I'm guessing another 3 weeks to go as pic is of a less mature bud.
Boron deficiency/lockout.
The photgraph seems to match this one very closely.
https://www.zambeza.com/blog-how-to...ts-are-suffering-from-a-boron-deficiency-n149
- When
"Boron deficiencies appear mostly in cannabis plants that have not been watered adequately or that are growing in a very arid environment with very low humidity."
- pH
"boron seems to be best absorbed below 6.5"
Uh oh, the dreaded boron deficiency. Once the lid gets lifted from the micro nutrient box you don't know what's going to spring out.
Most of the time boron deficiency is a symptom of a problem, usually PH related. High humidity contributes. Besides the bronzing at the top of the plant the growth will start to twist. You might see swelling at the base of the stalk, which might eventually crack and rot.
It looks like you're taking good care of your garden, from your description we can eliminate a lot of stuff. I don't think it's grey mold for instance. I'm guessing wind burn, it's the simplest explanation and it looks like what you've got. Boron is a good guess, it's a common one but your PH is where it should be. I hate trying to correct nutrient problems this late in flowering.
Now that you've raised the fan you'll know in the next day or two if it's wind burn. Notice in the pictures of the boron deficient plants the leaf tips are twisting up, yours are neutral or pointing down. Wind burnt leaves will claw downwards. Keep checking your PH and watch for twisting. Let us know if it gets better or worse, curious how it'll turn out.
Here's a link I found to an article about wind burn. Check out the video half way down.
https://www.growweedeasy.com/cannabis-plant-problems/wind-burn
Most of the time boron deficiency is a symptom of a problem, usually PH related. High humidity contributes. Besides the bronzing at the top of the plant the growth will start to twist. You might see swelling at the base of the stalk, which might eventually crack and rot.
It looks like you're taking good care of your garden, from your description we can eliminate a lot of stuff. I don't think it's grey mold for instance. I'm guessing wind burn, it's the simplest explanation and it looks like what you've got. Boron is a good guess, it's a common one but your PH is where it should be. I hate trying to correct nutrient problems this late in flowering.
Now that you've raised the fan you'll know in the next day or two if it's wind burn. Notice in the pictures of the boron deficient plants the leaf tips are twisting up, yours are neutral or pointing down. Wind burnt leaves will claw downwards. Keep checking your PH and watch for twisting. Let us know if it gets better or worse, curious how it'll turn out.
Here's a link I found to an article about wind burn. Check out the video half way down.
https://www.growweedeasy.com/cannabis-plant-problems/wind-burn
Thanks guys! This is my 7th run in this setup with no major issues until now. I admittedly did put fan directly on plant as my cousin had some PM issues with this strain in past.
Temps are a bit higher than I thought at 24.5C. My analog gauge is giving me humidity at 42% and digital is saying 60%. Obviously one is no good so will look at ordering something tonight.
Im hoping these pics are better and you can see how fan was setup. Please excuse the crappy trimming as life got busy and she sort of got away from me.
So to this point I have done the following...
1 - pointed fans upwards at lights
2 - moved light to the 2 ft mark but still 100% - Should I cut it back?
3 - Res change - Current ppm at 530 with a ph of 6.0. She is drinking well and I can top up tomorrow and drop ph a bit more. Think I should bump nutrients a bit? I was adding 5ml of calmag per gallon up until about 3 weeks ago. I added none when I changed res.
Temps are a bit higher than I thought at 24.5C. My analog gauge is giving me humidity at 42% and digital is saying 60%. Obviously one is no good so will look at ordering something tonight.
Im hoping these pics are better and you can see how fan was setup. Please excuse the crappy trimming as life got busy and she sort of got away from me.
So to this point I have done the following...
1 - pointed fans upwards at lights
2 - moved light to the 2 ft mark but still 100% - Should I cut it back?
3 - Res change - Current ppm at 530 with a ph of 6.0. She is drinking well and I can top up tomorrow and drop ph a bit more. Think I should bump nutrients a bit? I was adding 5ml of calmag per gallon up until about 3 weeks ago. I added none when I changed res.
Attachments
Sure looks the same doesn't it. Entire grow has been with tap water, ph has been staying stable at 5.7 to 6 the entire grow.
Entire grow is in a dry basement with central a/c. I believe humidity levels are low 40s but need a new meter. I have been guilty of letting res get below half often so maybe that is also contributing.
