According to their website, it has no harmful ingredients and leaves no harmful residues in strict parts-per-billion testing. I didn't have burn issues and had 6 different strains that I drenched thoroughly, several times, when I had spider mites last year (which LCPT quickly eradicated). This is how I'd interpret the directions for 1.5 quarts of water:
- According to the directions, it says 12 oz of LCPT per 12 gallons water
- This means 1 oz per gallon of water
- This means 2 TBSP per gallon of water
- This means 0.75 TBSP for 1.5 quarts of water
If my math is correct, you had it about 33% stronger than the package directions, not sure if it makes a difference though.
On their FAQ page, it says the following to answer the question, "What causes burning?":
It is very hard to burn or stress plants with our product. There are a variety of factors that can contribute to burning below are the only ones we know of related to our product.
Do not apply Lost Coast Plant Therapy in high heat (80 degrees or higher) or mid day high heat. Even plain water can burn plants if applied during high heat.
We suggest you water your plants the day before use of Lost Coast Plant Therapy if possible.
Make sure your sprayer/applicator line is clear of old product or other people’s product. Residue of other products can burn your plants. Mixing out product with other people’s products can have unknown interactions, so we do not guarantee what mixing our product with other product will do.
Our product separates, so if you spray without mixing you can get a high dose of one ingredient. Always mix well before and during application.
Hope this helps, let us know how it goes if you continue to use it. Cheers.