There are many ways to lose profits when cultivating cannabis but the worst way is watching pest and disease destroy all of your hard work. The list below is taken right out of Ed Rosenthal’s Marijuana Pest & Disease Control book.

In 1668 Francesco Redi disproved the theory of spontaneous germination. This means that pests and diseases don’t just happen.  They are the result of parent(s) and must have a source of origin. Here are some steps to use to prevent bringing them into the garden.

1. Wash and wear clean clothes if you have been outdoors or in another garden.
2. Don’t allow indoor/outdoor pets in the garden.
3. Quarantine all new plants for 10 days in a separate space before you allow them in the garden. You might treat them with an appropriate pesticide just to make sure they are clean.
4. Place a welcome mat in a tray and keep it wet with salt water, Step on the mat before you enter the garden space to prevent hitchhiking pests and diseases.
5. If you use ventilation in the room filter the incoming air with a thrips or hepa filter and use a UVC sterilization light in the ductwork.
6. Remove all leaks and make sure that water doesn’t puddle so diseases don’t have an incubation area.
7. Use appropriate spacing between plants to allow air-flow.
8. Keep the garden at 50% humidity or less to prevent bud-rot.
9. Spray with a combination of potassium bicarbonate (or sodium bicarbonate, baking powder) and 10% milk to prevent powdery mildew.
10. Keep a “dead-zone” of at least 5 feet between your garden and other plants.
11. Use beneficial nematodes to kill soil dwelling insects such as root aphids as well as soil-dwelling larvae of fungus gnats and thrips.
12. Use a barrier such as paper or coco-mats between canopy and soil to prevent fungus gnat and thrips larvae from reaching the soil when they drop from the plant.

There are many more nuggets of gold in Ed Rosenthal’s Marijuana Pest & Disease Control book available here.