Of all the stuff I've tried on spider mites, the most effective treatment is the ordinary garden hose. It's just too bad I can't use it inside (yet!), but I hose down my outdoor plants every other day. Doesn't kill them all, of course, nothing does short of fire.
I had mold on my apple tree seedlings, and none of the sprays I tried worked at all. I mixed a 50% milk and water spray, and that killed the mold after a week of daily spraying.
Not much experience with other pests, but I doubt there's really a single spray to handle them. There are tons of products making that claim, though. Soap sprays are the most effective against the most pests, though the bugs become resistant to a given spray pretty quick.
In my research the most people who claim lasting success use a variety of treatments, soap, plant extracts like citrus and rosemary, alcohol, etc. I see evidence of this in product reviews too. The 5 star reviews often have a grocery list of other things tried that worked a little but didn't last, then suddenly this one product killed them all. It must be magic.
As a warning, SNS makes a product called 217c. It is a foliar and root drench product made with rosemary. It will make your weed taste like potpourri smells. You might think that is a cool flavor. It is not. It was successful for me with controlling the ‘borg(I used it as a root drench for 2 grows after using the Dr Zymes and Power Wash to keep my plants free of the mites) but it as unpleasant weed to smoke. The issue may be I used it during flower but it isn’t worth trying it again only in veg for me…
Foliar feeding does not replace the normal process by which plants uptake nutrients. This happens through your plants’ roots that are embedded in soil or some other growing substrate. Foliar feeding, however, can be a very effective way of supplementing nutrients in the short-term. It is particularly effective if you want to provide your plants with secondary nutrients like magnesium or calcium. It is also a very beneficial way to provide zinc, iron, manganese and other micronutrients to your plants.