Newbie needs help diagnosing yellow spots

Hello everyone

Hello everyone,

This is my first post. I'm a newbie, having a problem with my first grow. First let me extend a sincere thank you to everyone on the forum. I’ve gotten a lot of help here over the last few weeks. Your help is much appreciated.


I’m having a problem with one of my plants and I’m not sure what’s causing it. The leaves have a lot of little yellow-brown spots. It is worst along the edges. In fact the edges have started to dry out and crumble.


Details:

I have a very modest set-up.
Lighting: 400 watt MH, 18/6
Medium: potting soil mixed with perlite
Temp: - Mostly in 70’s, although the 1st two weeks it was much higher
Humidity: 45-55%
pH: I have a tester but haven’t used it yet, somewhere I read not to worry about it for the first month or so
Water: - every 2-3 days. I let the top part of the soil dry out completely. I’m trying not overwater.
C02: nope
Ventilation: I turn a fan on periodically everyday
Nutes: I just started using guano at ½ strength. The problem started before I started using the nutes, so originally I thought it could have been an N deficiency, but it hasn’t clear up.


The plant, (Blue Appolo grown from seed) in question is almost a month old. As I mentioned I have a very modest set-up (5 plants: 3 Blue Apollo, and 2 Atomic Haze) Two of the plants are six weeks old and three are four weeks. The problem plant is in the smallest container. I was going to transplant it once it gets larger. It was also the closest to the lights, about 18-24 inches away.

Any suggestions? The problem has started to spread to one of the other plants, so I could really use some help.


Thanks

Kokuma

^^^

Apologies for the bump but the post seems to have made it to the abyss of the 2nd page

Thx
Kokuma

Looks like nutrient burn to me. Either it has been splashed onto the leaf or you have added too much nutrition to this young plant.

What I don't understand is that this started before I added any nutrients.

The plant was in potting soil mixed with a little perlite, nothing else. I believe potting soil might have some nutrients already in it, but enough to cause a problem? If some how the soil was to blame, wouldn't the other plants have the same symptoms? Please keep in mind the main afflicted plant is in the smallest container.

Note: 1 other plant is starting to have yellow spots develop but this started after I started adding guano. I've only added guano twice, both times 5 plants split quart of water that had 1/4 teaspoon of guano soaking in it. That is roughly 1/2 the does suggested on the package. Is that really too much fertilizer?

Additionally nothing, not even water, has been splashed on the leaves.

Any other thoughts? What could have cause the nutrient burn, before I added them?

Thanks
Kokuma