Something on underside of basil leaves – but what?

[Low Altitude]

Hi all.

This may be the dumbest question ever asked, but is this an infestation of some kind, or just good old dirt?

It's on the underside only of leaves of a basil plant I bought a week ago that seems otherwise healthy. The upper sides of the affected leaves are yellowing, which is what made me notice it.

Thanks!

 

[Tetters]

I think your Basil plant is a bit out of date really. It`s an annual plant, and will be on it`s way out at this time of year. The plant could be carrying sooty mould which would account for the yellowing of the leaves. It might be a good idea to sow some seeds in the spring for next year.
Welcome to the forum

 

[Low Altitude]

Interesting! Thanks! I have a bit of a hard time with seeds here indoors, and I don't have any outdoors; but what the hey, I'll try.

 

[Tetters]

It isn`t very difficult, and you can use a window ledge

 

[roadrunner]

Lately I've been germinating seeds on napkins; I just find it easier, since I can pick and choose which plants seem strong growers based on way they germinate. I then just pick them up with some tweezers and place them in a homemade biodegradable pot until they get big enough to plant.

Here is a video showing basically how I germinate the seeds.

 

[nbergeronthomas]

Personally, I would spray it down with Neem Oil just to be safe. It kinda looks like small webs which could be spider mites, but then the way the darkness is spread out makes me think otherwise.