Strange white deposits on stems

[lemonade]

I noticed these white spots on some stems today. At first I thought it could be salts from nutes splashed on the stem when watering but I've noticed these deposits higher up on the plants far away from the soil.

I checked them out under a magnifier and they look sorta crystalline. The white stuff can easily be rubbed off. I didn't see any bugs or anything under the magnifier, or penetrations of the stem. Is this insect or nutrient related? I'm using Floranova bloom (6ml/gal) and LK (10ml/gal) in a soilless mix (promix/perlite).

Anyone know what this is?

 

[Chiefsmokingbud]

Kinda Looks like the beginning of Powdery mildew but it usuallt starts on the leaves and not the stems. Is it also on the leaves? What is your humidity?

 

[Bøf]

I would say mildew also.. am struggeling with it myself. Mine did start at the stems also, then about a few weeks later it had spread to the buds and destroyed almost all my plants.. It never really showed on the leafs untill my next grow, now my room is kindda infected.. it sucks!

 

[lemonade]

Thanks for the responses guys but I don't think this is PM. None of the leaves show any signs and the RH is quite low, around 45-55.

Also as you can see in the second pic parts of the stem near the white shit look sorta bruised. I've never seen this before. I've dealt with almost every other pest/problem in the book over the years but I've never seen this.

Other than this white stuff the plants seem OK for now. Growth seems a little slower than usual. This could be from cooler temps though. We're at around day 26 of flowering. These will probably go 70 or 80 days total so I'm really praying this white shit doesn't spread.

 

[Bøf]

Are all your stemms bruised? maby its just that one plant.. I'm gonna follow this one. I wanna now what this is..

 

[Chiefsmokingbud]

PM will discolor a plant underneith it and around the PM, after all it feeds off it. If it's like a chalky powder i would bet it's PM. The solution is simple if you catch it fast. I believe it's 1 TBS baking soda to a gal of water and hose it down.

 

[lemonade]

Yea I'm quite familiar with PM as I used to live in the PNW.

In the past I've tried all sorts of remedies like baking soda water, diluted milk etc but the only thing that was effective was sulfur and keeping the RH way down.

I still don't think this is PM though. It just looks slightly different in person.
It does look like PM in the pics though, so I can see why you'd think thats what it is.

This stuff is a lot "thicker" and it looks crystalline under a scope. I've never had PM this white either, its usually more pale/cloudy and more spread out/dissipated, not just like a chunk here or there.

Also I've run this strain outdoors in very wet/humid conditions and never had a problem with PM, though OD is a different ball game obviously.

Fuck i really don't know what this is now. Ah well well see, I'm gonna set the dehumidifier a little lower and bring the RH down to 40-45 and see if that helps.

Thanks for the input guys.

 

[siren420]

lemonade, I also have these spots on my stems and am curious as to what it is. I have mixed bagseed growing in mix of local soil and mg... have used superthrive and growing under cfl. The humidity is very low.. around 50%.

 

[stinkyattic]

I can't open the pics but what about the possibility of adventitious roots?
Try just for sh*ts n giggles slicing a rapidrooter in half and taping it around a stem with those nubs- see if you get actual root growth.
Edit: 50% RH is not low by any means. Air-rooting becomes more likely as ambient humidity increases.