White fungus? on soil

(Question)

Hi,
I am trying to grow basil from seed and about a week ago shoots appeared. When the soil in the pot got dry, I watered it but now a strange white film, which I am guessing is fungus, has appeared on the surface. What do I do?

I am currently growing the seeds indoors with a plant light which I leave on for at least 12 hours a day. The area where the plants are does not have any drafts but the heating has been on intermittently keeping the air fairly dry. I have other pots in the same location and they do not have the film/fungus on them, just the basil shoots.

I planted the shoots in a store bought potting mix in which I also put some organic fertilizer. Only the bail pots had the fertilizer in them.

I do have a small area outside where I can keep the plants but have not done so as yet as I have felt the temperature has been unreliable on most days. This area gets sun in the morning and early afternoon, but is in shade by late afternoon.

I would appreciate getting advice on this matter and hope that I don’t have to start from scratch!

Thank you

(Answer)

You are right to suspect a fungus. You are also right in wanting to address this problem as unchecked fungus can spread to other plants in the vicinity.

It is hard to tell from the photo whether the fungus you refer to is on the soil or on the plant. If it is appearing on the soil it may be prudent to repot.  When you repot the plant take care not to handle the stems as this could damage the young plants beyond saving. Use potting soil for seedlings. Then follow the care directions provided below. Hopefully this will prevent the fungus reappearing.

If the fungus is appearing on the plant itself it is most like a powdery mildew. This is a fungus that prefers conditions where plants are suffering from water stress (caused by either drought or erratic watering) with light moisture over the leaves. It is usually young soft foliage that is most vulnerable.

Keep plants well watered (water from the bottom of the pots) and allow for good air circulation. Inadequate ventilation around plants is a very important factor in promoting the spread of fungal disease so if you have one maybe introduce a fan into the area?  If the fungus does return to the plant pick off any infested leaves if you can and grow on. In late May the plants can be moved out doors.

Looking forward, try to select resistant cultivars if you can find them. Good luck with your basil.