Prevention

Marijuana Horticulture

by Jorge Cervantes

Cleanliness is the key to insect and fungus prevention. The grow room should be totally enclosed so the environment can be controlled easily. Keep the floor clean. Keep all debris off soil surface. Do not use mulch. Insects and fungi like nice hideaway homes found in dirty, dank corners, and under dead decaying leaves or rotting mulch. Growers and their tools often transport many microscopic pests, diseases, and fungi that could ultimately destroy the garden.

This does not mean growers and their tools have to hospital clean every time they enter a grow room, even though that would be nice. It does mean normal and regular sanitary precautions must be taken. Growers who wear clean clothes and use clean tools reduce problems considerably. A separate set of indoor tools is easy to keep clean. Pests, diseases, and fungi habitually ride from plant to plant on dirty tools. Disinfect tools by dipping in rubbing alcohol or washing with soap and hot water after using them on each diseased plant. Another quick way to sterilize pruners is with a hand held torch. A quick heating with the torch will sterilize metal tools immediately.

Personal cleanliness is fundamental to preventing pests and diseases. Wash your hands before touching foliage and after handling diseased pants. Smart growers do not walk around buggy outdoor gardens and then visit an indoor garden. They do it vice versa. Think before entering an indoor garden and possibly contaminating it. Did you walk across a awn covered with rust fungi or pet the dog that just came in from the garden outside? Did you just fondle your spider mite infested split leaf philodendron in the living room? Avoid such problems by washing your hands, and changing shirt, pants, and shoes before entering an indoor garden.

Once a crop has been grown in potting soil or soilless mix, throw out the growing medium. Some growers brag about suing the same old potting soil over and over, unaware that these savings are repaid with diminished harvest. Used soil may harbor harmful pests and diseases that have developed immunity to sprays. Starting a new crop in new potting soil will cost more up front but will eliminate many potential problems. Used soil makes excellent outdoor garden soil.

Be careful when discarding used soil! Growers in Eugene, Oregon, tossed their outdoor soil out in the backyard for many years. The soil was about 50 percent white perlite and had a distinctive color. This oversight eventually led to the growers’ arrest.

Once potting soil is used, it loses much of the fluff in the texture, and compaction becomes a problem. Roots penetrate compacted soil slowly, and there is little room for oxygen, which restricts nutrient uptake. Used potting soil is depleted of nutrients. A plant with a slow start is a perfect target for disease, and worst of all, it will yield less!

Companion planting helps discourage insects outdoors. Pests have nowhere to go indoors, so companion planting is not viable in the grow rooms.

Plant insect and fungus resistant strains of marijuana. If buying seeds from one of the many seed companies, always check for disease resistance. In general, Cannabis Indica is the most resistant to pests, and sativa is more resistant to fungal attacks. Choose mother plants that you know are resistant to pests and diseases.

Keep plants healthy and growing fast at all times. Disease attacks sick plants first. Strong plants tend to grow faster than pests and diseases can spread.

Forced air circulation makes life 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 the 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.

Indoor horticulturist 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 t wipe out an infestation. If pests and diseases are left unchecked, they can devastate the garden in a few short weeks.