My best guess ...and that's what this is, I would say light burn try raising /dimming light

Burn.....sit'em in the dark a while. 70rh and 70 rt. Worked out fine for mine.

First off autos are not photoperiod plants you do not transplant and running multiple stains can be a hassle bc the tallest plant will force you to raise your light and smaller strains will suffer, yes you can put shit under the pots to raise them but is a hassle, give a light flush and check pH I bet it's off, I only feed my autos botanacare pro grow then very lightly after 3 weeks, 1ml per USgal, it's basically fish mulch and nitro, after you water and drain and check pH, I fill a 16oz cup of water shake jug add a small splash to cup and feed, with autoflowers less is better, for flowering I use Atami Bloombastic 1/2ml per USgal same drill but go light or you will fry them, Pic 1 is 86 day old auto alien vs Triangle x strawberry nuggets will chop Saturday, have 2 double grape and 1 sweet strawberry mango crumble running, pics are random autoflowers, I'm trying to show you you do not have to feed or give all sorts of stuff to run autoflowers, all you need is good dirt like ffof, good drainage, a light food, and a good flowering agent, other than that you do your best not to stress them, some do not mind pruning some will slow up for a day or 2, you want ur branches in the light leaf tuck before pruning, then let them alone and let them do there thing in my humble opinion.

Tipshades said:

This is my first time growing... the plants seemed to be fine about 2 or 3 days ago now they all seem to be turning dingy brown/yellow on the pistils and leaves and also giving off a not so pleasant smell... any help is GREATLY appreciated, I'm getting super worried!!!

4 plants in a 3x3 tent with a MarsHydro TSW 2000
2x Gelato, 1x Wedding Cake and 1x Zkittlez all autoflower on day 48
TSW 2000 is at full power hanging around 20-24 inches from the canopy on an 18/6 schedule
Plants are in 3 gallon fabric pots and get about half a gallon of water every other day (I use the pickup method to see when they are dry)
Temperature = Usually around 70-75 / Humidity = 40% -60%
I'm using Botainicare Nutrients as follows and pH the water between 6-6.5... I feed nutes once then the
next 2 watering are just water then nutes again
Bloom for soil = 5ml per gal
CalMag = 2ml per gal
Rezin = 2ml per gal
*I stopped all nutrients and having been giving only pH water since I noticed the problems (about 2-3 days ago)
I have a 4 inch AcInfinity exhaust fan with a carbon filter and I usually leave the tent door open with a fan blowing in

Click to expand...

Auto flower can be unforgiving due to the short time it takes to grow; are you measuring your ppm? The light yellow leaves could be indication of nitrogen deficiency and once your feeding her check the runoff it will let you know what’s the ph of the soil and also the ppm reading so you can see how much nutes are in the soil.

You need to check your pH everytime you water,, but yellow leaves starting at top of plant is 1 of 2 things, a nitro deficiency or more likely you are overfeeding, you must wrap your mind around the fact that autos are very fussy and need much less nutes than a photoperiod plant, some strains are allot more fussy than others, while late in flower it is common for the main leaves to yellow out the sugar leaves will not, since I told u not to run multiple strains as some look much better the ones yellowing are more fussy when it comes to nutes, I see a slight very slight discoloration on some of your leaf tips that's good bc your plants are at max uptake, what I mean is your feeding them right to the point if you gave more they would burn, as for the plants with the yellow leaves give a very light flush and check your pH correct if nessasary and cut back on the nutes and you should be OK, here are 2 pics of what I'm running the larger plant is in light pre flower, then I ran a different strain but I have been growing these things 10+ years, pH is 6.2 & 6.1 respectively note the health of plants, all I ever give them is botanacare pro grow when they stop growing vertical and start showing trichome I remove from tent flush out and put in flower closet and give Atami Bloombastic both doses are 1ml per USgal then watered down, at first dose of Atami I go very very light and observe the plants bc autos are notoriously easy to burn usually in flower bc all botanacare pro grow is is fish mulch and nitro they luv it it's very light and never burned an auto in veg, remember they are on there time not yours do not listen to breeder or bank, the tall plant is in light pre flower but the smaller one is just starting, that is why I advised you not to run multiple strains you run into trouble last Pic is strawberry mango crumble I'm about to chop, just remember autos need very little nutes what 1 strain likes will fry another, all you want to do is keep them in good health till they top off and start to show trichome then you flower them, there not photoperiod plants and not run the same.

Always back off your lights at first sign of stress - (I also run tsw 2000 x2 and tsw 3000 x2) 18-24" full power for 18Hrs = your burning them.

Advice raise the light to 30" this where it should stay.
Turn light back to 75% until they recover(5 days), then go to 80% stay there, if no issues 90% and so on.

good luck