Marijuana Horticulture: The Indoor/Outdoor Medical Grower's Bible

miserable for pests and diseases. Pests hate wind because holding on to plants is difficult, and flight paths are haphazard. Fungal spores have little time to settle in a breeze and grow poorly on wind-dried soil, stems, and leaves.
    Ventilation changes the humidity of a room quickly. In fact, a vent fan attached to a humidistat is often the most effective form of humidity control. Mold was a big problem in one of the grow rooms that I visited. The room did not have a vent fan. Upon entering the enclosed room, the humid air was overpowering. It was terrible! The environment was so humid that roots grew from plant stems. The grower installed a vent fan to suck out moist, stale air. The humidity dropped from nearly 100 percent to around 50 percent. The mold problem disappeared, and harvest volume increased.

Healthy plants are easy to keep strong and are able to fight off pests and diseases.
    Indoor horticulturists who practice all the preventative measures have fewer problems with pests and diseases. It is much easier to prevent the start of a disease than it is to wipe out an infestation. If pests and diseases are left unchecked, they can devastate the garden in a few short weeks.
Control
    Sometimes, even when all preventative measures are taken, pests and diseases still slink in and set up housekeeping. First, they establish a base on a weak, susceptible plant. Once set up, they launch an all-out assault on the rest of the garden. They move out in all directions from the infested base, taking over more and more space, until they have conquered the entire garden. An infestation can happen in a matter of days. Most insects lay thousands of eggs in short periods of time. These eggs hatch and grow into mature adults within a few weeks. For example, if 100 microscopic munchers each laid 1000 eggs during their two weeks of life and these eggs grew into adults, two weeks later 100,000 young adults would lay 100 eggs each. By the end of the month, there would be 100,000,000 pests attacking the infested garden. Imagine how many there would be in another two weeks!
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Logical Progression of Insect Control
    1. Prevention
         a.  Cleanliness
         b.  Use new soil
         c.  One indoor set of tools
         d.  Disease-resistant plants
         e.  Healthy plants
         f.  Climate control
         h.  Companion planting
    2. Manual Removal
         a.  Fingers
         b.  Sponge
    3. Organic Sprays
    4. Natural Predatorsg. No animals
    5. Chemicals
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Manually remove small populations of pests by smashing pests and eggs between your fingers. Make sure to wash your hands afterward.

A 30X battery-powered magnifying scope makes insects and diseases easier to identify.
    Sprays often kill adults only. In general, sprays should be applied soon after eggs hatch so young adults are caught in their weakest stage of life. Very lightweight (low viscosity) horticultural oil spray works well alone or as an additive to help kill larvae and eggs.
    The availability of some sprays can be seasonal, especially in more rural areas. Garden sections of stores are changed for the winter, but extra stock is sometimes kept in a storage room. Look for bargains on sprays at season-end sales. Today, there are many indoor grow stores that carry pest and disease controls all year round.

Insect Control
    Indoor gardeners have many options to control insects and fungi. Prevention and cleanliness are at the top of the control list. A logical progression to pest and disease control is outlined in the chart on this page. (Note that it begins with cleanliness!)
    Manual removal is just what the name implies–smashing all pests and their eggs in sight between the thumb and forefinger or between two sponges.
    I like natural-organic sprays such as pyrethrum and neem and use harsh chemicals only as a last resort. Any spray, no matter how benign, always seems to slow plant growth a little. Stomata become clogged when foliage is sprayed and covered with a filmy residue. Stomata stay plugged up until the spray wears off or is washed off. Stronger sprays are often more phytotoxic, burning foliage. Spray plants as little as possible and avoid spraying for two weeks before harvest. Read all labels thoroughly before use.

Yellow sticky traps are used to monitor pest populations as well as to control small flying insects.
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Common chemicals with their trade names and the insects they control:
    Note: Do not apply