Black blobs underneath basil leaves

[lizerdbits]

I don't normally post here since, well, I don't have a garden in my condo. I do have a small patch of dirt outside that according to my mother (who actually gardens) only gets enough light for mint.

I have some potted basil, thyme, sage, and oregano growing inside and the basil leaves have some black/brown blobs on the underside of the leaves. Does anyone have a guess as to what this might be? Fungus? The only window that gets enough sun for growth has an AC vent right below it. Could I have something circulating in my air? It's been pretty hot and humid lately so I haven't had my windows open in several weeks (I've had the plants about a month). I don't know if this is also a problem for basil grown outside.

Thanks to anyone who can help! :hi:

[Dover]

1. Hmmm....doesn't sound familiar. Can you take a picture and post it?

In nature basil is susceptible to Japanese beatles, aphids and fusarium wilt, none of which seems to be your problem. Unless it's an overwatering issue, it may be an 'unnatural problem' caused by the ac unit or light conditions. Do you use growing lamps in conjunction with the natural light? It likes full sun and is sensitive to cold (which might turn leaves black). Also try not to wet the leaves when you water, just the soil.

Another possibility is black spot. Might take it to a decent garden center and ask them, since they have the advantage of actually looking at it.

This website might be helpful -
http://www.lifescript.com/channels/healthy_living/Life_Tips/growing_basil_at_home.asp?trans=1&du=1&gclid=CLqK6aDHu5QCFQRksgodriH7Tg&ef_id=1350:3:c_7df48f6e4598ea8cc9cb674450fe17ca_1951744595:dDABhEo-JyoAAEh80sMAAAAN:20080712235950

Also might do a google search for "growing herbs indoors", or something like that.

[lizerdbits]

2. Unfortunately I removed them so I can't get a pic

If they come back it's probably something infectious and I'll have to figure out what it is. I googled images of various pests I came across and didn't find anything that looked like it. That link was also helpful!

They are in pots with plastic dishes underneath so they can drain. When they're dry I water (soil only) and come back in about an hour and get rid of the excess, if any. They are getting about (I'm guessing) 6 hours of direct light at this time of year so I'll need some artificial light in later months. From what I read it sounds like basil needs 8 anyway so I should start looking into that now. As for the cold, I could close that vent (it's a second bedroom I don't use for much) or see if I can move the rack they are sitting on out of the air flow. I have my air set on about 78 and the thermostat is downstairs, it's probably a little over 80 upstairs.

Thanks for the help!

[Dover]

3. Yeah I'd start with the ac and the light issue and see if things improve.

The heat from the sun and the coolness from the ac are sending mixed messages...lol! Very confusing for a little basil. Sounds like turning off that ac vent will be good for the basil and your pocketbook.

If you can put a growing lamp on it for the hours that it is not in the sun, that might help.
You can get relatively cheap timers to attach to the light outlet so you don't have to manually turn it off and on everyday.

Good luck!

[lizerdbits]

4. A coworker said possibly sap suckers

Google images looks like a match, but mine were just on the leaves.

http://aqualandpetsplus.com/Plant,273.jpg

Being the science dorks we are, I'll be taking one in if I find another for microscopic examination.

[Dover]

5. Icky! So glad you figured it out. Well if that's what it is, how will you treat it?..n/t

[lizerdbits]

6. Since I plan on using the basil for cooking...

she recommended putting them in the same pot with some marigolds. I'm not sure exactly how the marigolds will reduce/eliminate the sap suckers but I'll take the word of a woman who's been gardening for decades. As luck would have it, someone left some larger pots in our lunch room 'free to good home' which I took so I may have one big enough. So I'll get some this weekend.

For non food plants she said she would use a pesticide in the soil that would be taken up through the roots to keep them off the leaves.