Do you have persistent problems? I find most of these foliar sprays don't do much.
If you get somethign like WPM it will not be effective, because tehre is nothign out there that is effective even on large commercial farms, whicc have access to far stronger fungicides than anything you can buy over the counter. A lot of this stuff has a super high premium price too.
I'd read the ingredients and look for an alternative if it is one of those overpriced magical products. chances are you can find a concentrate by someone else and get a 2 dollar bottle to mix up batches.
From their own literature,
"How does it work?
When you spray CANNACURE, it forms a second natural ‘skin’ on your plants. This layer improves leaf colour and vigour and while ensuring that the plants can still breathe. It makes them healthy, shiny and clean, enabling optimal photosynthesis. This gives the plants the chance to focus on flowering."
sounds like it's just some horticultural oil and maybe some magical ingredient that has no strong effect.. like peppermint or some natural shit that won't do much to keep mold or pests away.
The best way to avoid mold is to avoid the dew point. the best way to avoid pests is to keep a clean grow space -- anything that has larvea in the soil can be controlled with something called "Bti (israelis subspecies). It's a bacteria that's been used on the worlds foodcrops for a century or so? Meaning it's very safe to use. It's a bacteria that will kill the larvae. "Summit" is the brand name in north america and the products is called "mosquito bits" that are granulated bits you top dress or put into soil or "mosquito dunks" that you can use in a reservoir -- but it breaks down and can mess with plumbing.. better for a rain barrel or just a water tank than somethign you have pipes and shutoff valves or pumps involved. Though a mesh 'teabag' might work. Can break dunks down for a top dress method too.
So, probably just some horticultural oil would be just as effective as this canna cure.