Spots on leaves

[Jgutta420]

It’s probably too late in this grow but it’d be good info for future reference. I got these brown spots showing up with yellowing leaves in the last few days. Nothing different about feeding. Growing in DWC and give ff big bloom & tiger bloom and I also feed cal-mag at half dosage every other reservoir change. It’s only the top fan leaves connected to buds & the sugar leaves. All of the bottom leaves are unbothered. Looking at the leaf deficiency chart it looks to be a potassium deficiency but…reservoir is ph’d to optimal range and I’ve been feeding. Haven’t began flush yet. Any ideas or does it indeed appear to be a potassium deficiency? Should I be worried because the next place for it to go is my buds.

 

[gmo]

more calmag

 

[boo]

yup...

 

[Jgutta420]

Should I worry about it this close to harvest? I am about a week or so out…I was going to begin flushing in a few days. Will it ruin my bud?

 

[WeedHopper]

I use CalMag all the way thru flower. I don't flush. Don't get me started on that ********.
I never starve my girls of nutrients they need. There are plenty papers written by real Botanist that will tell you flushing is complete ********.
I fatten my girls up right down to the week I harvest. I have smoked weed that has been flushed and see no difference what so ever.
Now that's my opinion based on actual science. To each his own.

 

[Jgutta420]

Yea I know there’s a heated debate about that. I can’t argue with scientific evidence though if actual botanists have confirmed it makes no never mind. Logically it makes sense though as all of those nutrients would still be in the smoke. I have 100% tasted the difference in ghost & reaper peppers I’ve grown and heavily fertilized before harvesting some chiles. Perhaps cannabis is different. I’ll take your advice and feed more calmag. It’s weird I just fed it 2 days ago with reservoir change. She’s greedy

 

[WeedHopper]

She is hungry and trying to fatten up for you.

 

[oldfogey8]

My take on it(and I have always flushed because that is what so many people say to do) is in nature, before people started to even cultivate crops, the soil didn’t suddenly lose all of it nutrients as fruit ripened. Feeding to finish makes sense to me now. I tried it with my outdoor grow and my buds don’t taste like there are a bunch of chemicals in them. Plants only use what they need, right?

 

[CrashMagnet]

What is the reservoir temperature?

 

[WeedHopper]

My take on it(and I have always flushed because that is what so many people say to do) is in nature, before people started to even cultivate crops, the soil didn’t suddenly lose all of it nutrients as fruit ripened. Feeding to finish makes sense to me now. I tried it with my outdoor grow and my buds don’t taste like there are a bunch of chemicals in them. Plants only use what they need, right?

That is absolutely correct. Ask Big,,,he grows outside and would laugh at you if you told him he needed to flush.

 

[oldfogey8]

That is absolutely correct. Ask Big,,,he grows outside and would laugh at you if you told him he needed to flush.

Flushing is for toilets

 

[WeedHopper]

Exactly.

 

[Jgutta420]

My take on it(and I have always flushed because that is what so many people say to do) is in nature, before people started to even cultivate crops, the soil didn’t suddenly lose all of it nutrients as fruit ripened. Feeding to finish makes sense to me now. I tried it with my outdoor grow and my buds don’t taste like there are a bunch of chemicals in them. Plants only use what they need, right?

Theoretically sure. But perhaps outdoor crops get flushed with rainfall. Idk, I will keep the calmag going and see what happens. I wouldn’t have any idea if weed I’ve ever smoked was flushed or not. First grow so perhaps next time I’ll flush and see if I recognize a difference.

 

[Jgutta420]

What is the reservoir temperature?

I honestly have no idea…never measured it.

 

[WeedHopper]

Read this. This is science not Mythology.

https://www.marijuanapassion.com/threads/ready-for-flush.80068/post-1141273
https://www.marijuanapassion.com/threads/ready-for-flush.80068/post-1141274

CONCLUSION
In a first of its kind study, Rx Green Technologies evaluated the effects of flushing period on yield, potency, terpenes, mineral content, and taste characteristics of Cannabis flower. Overall, the length of the flushing period did not impact yield, potency, terpenes, or taste characteristics of Cannabis flower. Taste test results indicated a trend toward improved flavor and smoke quality with the zero-day flush. While there were no significant differences in nutrient content, there was a trend toward increased iron and zinc in flower flushed for 14 days. The results of this trial indicate that there is no benefit to flushing Cannabis flower for improved taste or consumer experience.

 

[RosterMan]

I honestly have no idea…never measured it.

Makes a huge difference

 

[CrashMagnet]

I honestly have no idea…never measured it.

DWC water temp should be below 70 deg IMO, ideally around 60 deg. New leaf deficiencies can be a sign of root rot or other temperature related issues. @gmo is our resident expert. I'm still way behind the learning curve on DWC issues.

 

[WeedHopper]

Yep. Even if you have to put some frozen bottles of water in the rez you need to keep the solution temps down. I know. When i was growing in Florida in DWCs i had to use frozen bottles of water to keep temps down. Othe wise your roots will turn yellow and start having problems with pathogens.

 

[oldfogey8]

It looks like according to this study, the only benefits to not flushing is a small increase in average taste preference. Flushing is cheaper since you use less nutrients. That may affect large scale growers I guess but for small scale growers it is probably a few dollars (if even that high). Before reading the study, I would have assumed greater yield if plants are fed up until harvest but it looks to be statistically insignificant(6 grams per plant higher for flushed plants). For me, taste would be my preference over about a 6% increase in yield when flushed. This study, though interesting, wouldn’t really put me on one side or the other of the fence.

 

[WeedHopper]

Fence rider.