Growers taking time to harvest a healthy cornucpoia of cannabis must also carefully watch over their cut crops. In addition to two-legged thieves, myriad bacteria, molds and insects have been known to rip-off your stash while curing, drying, or in the fridge. Avoiding these ubiquitous threats is nearly impossible, but there is a way to lessen their impact. The key is being able to manipulate storage conditions.
A variety of bacteria grow on damp marijuana. Many are deadly. Researchers have found Klebsiella pneumoniae, Enterobacter cloacae and Streptococcus (group D) growing in government-supplied reefer. Salmonella muenchen was found in marijuana growing across the Midwest. (Let someone else roll the joints. I don't lick rolling papers anymore!) Under anaerobic conditions (i.e., damp marijuana stored in airtight containers), Clostridium species will rot pot; these are the famous botulism bacteria.
In addition, a number of bacteria-like Actinomycetes have been identified in confiscated ganja, including Thermoactinomyces candidus, T. vulgaris, and Micropolyspora faeni. These bugs cause allergic reactions (sometimes severe), as well as "Farmer's lung" disease.
Insects in pot are less intense. Growroom critters, such as aphids and spider mites, rarely damage marijuana after harvest. Smith & Olson (a list of references appears at the end of this article) identified five beetle species from confiscated Mexican weed in San Francisco. They completed this study at the request of the DEA agents, whose offices were overrun by the pests. The predominant species, Tribolium confusum (confused flour beetle), attacks only seeds, not marijuana proper. Two other beetles cited in the study, Adistermia watsoni and Microgramme arga, are fungus feeders (the marijuana was moldy). Thankfully, the researchers found no cannabis equivalent to Lasioderma serricone, the tobacco cigarette beetle. Otherwise some whacked government lab would be growing the bugs en masse to spread across the continent.
Fungi destroy more bud than bacteria and insects combined. Bacteria in marijuana may be more dangerous to humans, but they are rare. Molds are common, and can be nasty: Ramirez reports four policeman developing pulmonary histoplasmosis after pulling up a 5,000-square-meter plot of marijuana in Puerto Rico. Some fungi won't rot pot, but they will put you in the hospital.
Many fungi causing disease in plants die off after their host is harvested. Exceptions include Botrytis cinerea (the cause of gray mold) and Alternaria alternata (brown blight). After harvest, your competition becomes Aspergillus, Penicillium, Rhizopus, and Mucor, the baddest actors on the planet. Each genus causes disease under different conditions:
Ubiquitous Aspergillus grows on anything from rocket fuel to astronauts. The genus is millions of years old; while Homo sapiens may come and go, Aspergillus will remain. Westendorp first found an Aspergillus species attacking Cannabis in 1854. More recently, Margolis & Clorfene describe a mold that increases potency in marijuana. Their "black weblike fungus" sounds like an Aspergillus species. What species, I'd like to know....
Schwartz scraped Aspergillus niger from the skull of a marijuana smoker experiencing sinus headaches. I frequently encounter A. niger growing in ganja stored at room temperature. It does not increase potency. Kagen also reports A. niger growing in moldy marijuana, along with two even nastier Aspergilli: A. fumigatus and A. flavus.
Chusid et al. blame A. fumigatus for causing near-fatal pneumonitis in a 17-year-old. They note the patient buried his marijuana underground for "aging." No doubt the patient was looking for Margolis & Clorfene's fungus, but A. fumigatus found him instead. A. flavus, on the other hand, kills slowly. It oozes carcinogenic metabolites called aflatoxins. Llewellyn & O'Rear found aflatoxins contaminating Virginian marijuana.
Aspergillus species grow better in warmer climates, Penicillium in cooler climates. Refrigerator storage encourages Penicillium infestation. Kagen et al. isolated Penicillium from marijuana cigarettes. Babu et al. identified P. chrysogenum attacking marijuana. (P. chrysogenum occurs abundantly in nature, and was Alexander Fleming's source of penicillin.) I isolated P. italicum from marijuana stored with an orange peel at 0 degrees Centigrade. Adding peels to pot imparts a "pleasant bouquet" (Frank & Rosenthal). In my case, the peel imparted a nidus of infection. P italicum, the "blue citrus mold," is notorious for its ability to spread by contact (i.e., "one bad apple spoils the whole bunch").
Five Mucor species have been described on Cannabis. Members of this genus grow fast and die young. One of them, M. hiemalis, regrettably bioconcentrates (and cannot metabolize) the herbicide paraquat from tainted substrates (Domsch et al.). Mucor's first cousin, Rhizopus, occurs in soil, ripe foodstuffs, and occasionally on people (especially diabetics). Grebeniuk isolated R. stolonifer from hemp stems. In an inoculation experiment, I quickly rotted some damp marijuana with a colony of R. stolonifer found growing on bread.
Rotting marijuana produces a spectrum of odors, from stale to musty to moldy. P. italicum perfumes a lavender bouquet, while A. flavus smells like a locker room. Clostridium bacteria stink like carrion.
Infested marijuana often darkens in color and becomes crumbly. Anaerobic bacteria turn marijuana into brown slime. Marijuana undergoing rapid decay may feel warm to touch. (At this stage your stash is ready for the compost heap.) Tufts of fungi are often visible in mold material. In marijuana stored in darkness, strands look white to light grey. Exposed to light, storage molds spawn millions of colored spores in velvet clumps. A slight tap sends these spores into great billowing clouds. Generally, Rhizopus and Mucor produce grey-black spores; Penicillium species are light blue-green; and Aspergillus species are dark green-black.
To check for aflatoxins, inspect your stash under a black light (in medicalese, a "Wood's Lamp"). Material contaminated with aflatoxin-producing A. flavus will fluoresce to a green hue under ultraviolet light.
To screen for insects, simply shake samples in a No. 10 steel sieve. Of course, not all bugs found in marijuana cause damage. Some are simply "innocent bystanders" caught during harvesting and die right away. Live (and chewing) insects are more suspicious. A hand lens is helpful for I.D.
Avoid damaging plants before they completely dry (even while they are in the ground and growing). Wounded tissues release exudates on which fungi feed and establish a foothold. Lucas says diseased and nutrient-deficient leaves (as well as old yellow leaves) produce more exudates than healthy leaves. Expect more mold problems in poorly grown plants.
The secret to stopping bacteria and mildew is moisture control. Even grey mold dies if plants are carefully and quickly dried. Oven-cured pot rots less than air or sweat-cured crops. Sweat-cured Cannabis (remember '70's Colombian?) maintains a "tradition" of Aspergillus contamination.
The oven-drying method inevitably leads to a harsh product. So most people air-dry by suspending plants upside down with enough space for circulation. Drying rooms should be cool and dry, preferably in uninterrupted darkness. (Most storage fungi require light to sporulate and spread.)
Living cannabis plants are about 80% water. Perfectly dried marijuana contains about 10%-15% water or moisture content (MC). Material below 10% MC becomes too brittle and disintegrates. Fungi cannot grow below 15% MC. Unfortunately, many growers market their crop above 15% MC. Cannabis, like corn flakes, is sold by weight, not volume. Tobacco farmers also allow their product to gain weight by reabsorbing moisture before sale. They term this risky business "coming into order." Recently purchased products should be redried. Freezer storage will not protect damp pot. Placing lemon or orange peels in stored marjiuana is discouraged, as they raise the MC above 15%. Dipping Penicillium-infested plants in a solution of baking powder will inhibit these acid-loving fungi but the product must be rapidly redried.
Maintaining stored marijuana at 10%-15% MC also discourages insects. Insecticides have no application in stored marijuana. Their residue pose a danger to customers. Also, water-based sprays will kill bugs but trigger a fungus infection by raising the MC. Fumigants (gas, not sprays or aerosols) contain no liquid, thus they do not trigger mold infestations. But they leave residues in air pockets of fumigated material. Big buds are full of air pockets. Poisons are very useful for disinfecting drying rooms, but only after the crop has been cleared out.
Low temperatures will "freeze" an insect infestation. However, with rewarming, many bugs continue their destruction. Another drawback to freezing above-15% MC marijuana involves the aforementioned exacerbation of Penicillium. Heating marijuana in a 66-93 degree Centigrade oven for 10 minutes will kill most pests. This also dries out the product -- again, the cornerstone of control. Marijuana should not be heated longer than 10 minutes or 93 degrees Centigrade to prevent THC oxidation.
Immunosuppressed individuals and asthmatics should never be exposed to molds, especially Aspergillus. People using medical marijuana should take extra precautions:
Ungerlerder et al. sterilized marijuana with ethylene oxide, reporting no loss of THC from fumigation. These researchers also irradiated their dope with high-dose Cobalt 60 (15,000 to 20,000 Gray Units!) with no loss of THC. This method is not recommended for novices.
Moody et al. evaluated waterpipes for smoking Aspergillus-contaminated marijuana. Unfortunately, they found only a 15% reduction in transmission of fungal spores.
In Chicago, goofy dudes spray their marijuana with formaldehyde. This kills insects and fungi, but at a price. The treated weed, known as AMP, causes anoxia and psychomotor retardation when smoked (Spector). According to Newsweek (Jan. 20, 1986), a few ill-intentioned dealers dipped marijuana in rat poison or insecticides like Black Flag or Raid. They called this product "WAC." Indeed. Have a nice day.