It could be mite damage, or even eggs of mites. Also, if its a color that shows through the back of the leaves, it could be a fungual rust of some kind. Neem oil or a pyrethrin spray can help. Fungus gnats, need two kinds of processes to rid you of them. A form of Bt is used as a soil drench to kill the root maggots, and for the flying bugs, yellow sticky traps layed down horizontally to catch the bugs. These nasies can infest every plant nearby the one thats infected. Its an on going battle in my garden every year too. Lately, I use beneficial nematodes every summer, and they seem to help reduce plant root damges.

Thanks, IÂll check the back of the leaf tonight when I get home to see if it is fungal rust. Regardless, I think IÂll cut off and dispose of the affected leaves in my fireplace.

IÂve been fighting the gnats with insecticidal soap and yellow sticky tape so far. Until your post I was not familiar with Bt. After reading up on it I can understand how it will help control the little buggers. IÂll look for some on my way home.

Very good information, thank you for sharing.

Bill

Hi ksrogers,

Well, the discoloration does not go through the leaf. On closer inspection it appears to be topical and raised a bit. The significant other had a fire on when I got home so whatever it was it has now been cremated.

Your input was greatly appreciated. I didnÂt find Bt at the one place I checked on the way home but will call around tomorrow. The war continues!

Bill

Bt comes in different strains and you need to look at the one that is specific in controlling the fungus maggots. It isn't a spray, but a liquid, mixed with water and watered into the soil. I simple soap spray may not help protect the foliage much. Because there is no discoloration on the back of the leaves, suspect its insect eggs. If they scrape off and don't leave serious scars on the leaves, that may be the clue. If you do spray leaves, a better choice is the neem oil. Here is a site that sells it seperate from a surfacent, so you mix it with the castle soap and add to water, then spray once per week to 10 days. II like using the yellow sticky traps indoors as thats were all my garden seedlings get started. When I see a single gnat, the traps get placed. They are also great to monitor the infestation. One time, it was so bad indoors that by a weeks end the 4x6 inch yellow plastic card was loaded with hundreds of them.

Here is the link.

Here is a link that might be useful: Neem seed oil.

Assuming the plants are still very small with only a few leaves you could probably just give them a good wash in the sink. If you put your hand over the soil you can wash each leaf and stem by rubbing between your finger and thumb with luke warm water and a smidgeon of soap. Then rinse. May be a two person job. I'm a great believer in washing plants before reaching for more expensive solutions. There is no need to destroy leaves just because they have a bug or two. Disease is a different story. Bay is perfect for washing because it has tough glossy leaves which youcan clean thoroughly. Regarding fungus gnats. They like damp soil so maybe you are keeping your baby bays too wet. It is winter and they would not be growing actively in their natural habitat. Just sitting it out til spring. Another tip is to get them outdoors as often as possible if the temperature is suitable. (Bays here cope with temps around freezing quite happily and can manage down to about -5c occasionally.)

Thank you Flora UK,

The infected leaves are ash now so washing will not help. I'll try your suggestion if it happens again.

Bill

Fungus gnats are often a symptom of overwatering, and spider mites often appear in warm, dry conditions. Overwatering can easily happen with bay laurel plants that are root-bound: the surface of the soil dries out frequently, so you water often, and the matted outer roots start to rot.

Check to make sure the plants are not pot-bound; if they are, trim all rotted roots, tease out all the matted outer roots, and move to a larger pot. Keep the plants in a cool, humid, well-lit spot, preferably 10°F (5°C) cooler at night, and don't fertilize until March. Water only when the top ½" of soil is dry. Use good, light potting soil and a pot with drainage holes in the bottom. If the air is stale, run a fan nearby to create a gentle breeze. Look out for scale as well, which also responds to neem. If possible, put them outdoors in full sun during the non-frost months, and during the day in spring and fall when the weather is warm. Good culture should keep away most problems.