Question

Yellow leave  

Yellow leave 2   Hi Melissa,

Sorry, I noticed that I accidentally added 2 pictures of the lemon plant. I will attach a picture of the tropical plant. To be honest I recently noticed that there is some water in the base of the pot. So maybe this old water is causing the spots? I will remove it.
I had another small question about the lemon plant; when the seed grew into a small plant the soil (they don't go on the plant) was infested with grey tiny bugs (about 1mm) the younger bugs cant jump, but the adult ones do. I have recently removed as much of the old (cheap and poor quality) soil as possible and replaced it with better quality soil. I also used a insecticide spray. Luckily the bugs disappeared, but yesterday I noticed one in under the pot in the base of the second pot. On first sight they don't seem to harm the plant, but I was worried that they might eat the roots or something like that. Do you have any idea which bugs they are and how I could get rid of them?

Thank you again, have a pleasant day!


Martina

Answer
Dear Martina, It probably is the standing water in the container that is causing the leaves to go yellow.  Be sure the plants are able to drain thoroughly and have no salt buildup on the inside of the pot.  Also, to some extent it is natural for plants, especially philodendrons, to lose older leaves and grow new ones.  In the second picture, the yellow leaf near the wall is an example of an old leaf dying.  The one in the top could be sun scorch by getting too much sun, or it could be because of the excess water, but be sure to remove it.  
Your bug description is excellent.  What you are seeing is fungus gnats, the scourge of all indoor plant growers.  They do eat the roots and damage them that way, plus they spread fungal conditions.  The best thing is to spray the plants with any insecticide containing NEEM, and be sure to drench the soil with the NEEM as well.  You will need to do this a few times to get the bugs that are off flying around when you are spraying, and any new ones that hatch.  I hope this information helps.  Good luck, Melissa