Really importante Please help (more datails)

I would stop spraying anything you are considering to smoke in the future, even if they say it is "safe". Gnats love mulch, so this may need to go. Also, your plants are showing symptoms of "nitrogen draw down" and occurs when mulches such as pea straw with a low carbon/nitrogen contents are used. The soil microbes will "rob" the soil of its nitrogen so they can break down the mulch, resulting in your plant missing out on the nitrogen. Best mulch to use is alfalfa meal/lucerne, as it has a high amount of both carbon and nitrogen, meaning it doesn't rob nitrogen from the soil. Otherwise, try using some supplemental feeding of the soil with chicken manure pellets or something similar under the mulch, to boost the available nitrogen. If the gnats are a really big problem, you may have to remove the mulch all together unfortunately. Hope this helps,... Organoman.