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Moldy Marijuana, The Straight Dope
from High Times

May, 1993

"HOW TO PRESERVE POT stopping bugs and fungi
before they damage your weed," by The Bush Doctor

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 boutlism 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 _Home 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. [Erowid Note: The citation for this claim "A Child's Garden of Grass" is not considered a reputable source of information. The claim that some fungus or mold might increase potency should be considered unsubstantiated and potentially dangerous. Mar 16 2010] 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.

DIAGNOSIS 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 thier 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.

Babu, R., A.N. Roy, Y.K. Gupta & M.N. Gupta. 1977. "Fungi associated with deteriorating seeds of _Cannabis sativa L._" _Current Science" 46(20):719-720.

Kagen, S., V.P. Kurup, P.G. Sohnle & J. N. Fink. 1983. "Marijuana somking and fungal sensitization." _J. Allergy Clin. Immunol._ 71:389-393.

Kurup, V.P., A. Resnick, S.L. Kagen, S.H. Cohen & J.N. Fink. 1983. "Allergenic fungi and actinomycetes in smoking materials and their health implications." _Mycopathologia_ 62:109-112.

Llamas, R., D.R. Hart & N.S. Schneider. 1978. "Allergenic bronchopulmonary aspergillosis associated with moldy marijuana." _Chest_ 73:871-872.

Llewellyn, G.C. & C.O. O'Rear. 1977. "Examination of fungal growth and aflatoxin production on marijuana." _Mycopathologia_ 62:109-112.

Moody, M.M., R.C. Wharton, N. Schnaper & S.C. Schimpff. 1982. "Do water pipes prevent transmission of fungi from contaminated marijuana?" _New England J. Med._ 306:1492-1493.

Ramirez, J. 1990. "Acute pulmonary histoplasmosis: newly recognized hazard of marijuana hunters." _American Jounal Medicine_ 88(Supplement 5):60N-62N.

Smith, R.L. C.A. Olson. 1982. "Confused flour beetle and other coleoptera in stored marijuana." _Pan-Pacific Entomologist_ 58:79-80.

Spector, I. 1985. "AMP: a new form of marijuana." _J. Clin. Psychiatry_ 46:498-499.

Taylor, D.N. et al. 1982. "Salmonellosis associated with marijuana." _New England J. Med_ 306:1249-1253.

Ungerlerder, J.T., T. Andrysiak, D.P. Tashkin & R. P. Gale 1982. "Contamination of marijuana cigarettes with pathogenic bacteria." _Cancer Treatment Reports_ 66(3):589-590.

Domsch, K.H., W. Gams & T.H. Anderson. 1980. _Compendium of Soli Fungi_. Two volumes. Academic Press, New York.

Lucas, G.B. 1975. _Diseases of Tobacco_. 3d Ed. Biological Consulting Assoc., Raleigh, NC.

Margolis, J.S. & R. Clorfene. 1975. _A child's garden of grass_. Ballantine Books, NY.

Westendorp, G.D. 1854. _Les Cryptogames_. I.S. Van Doosselaere. Gand, Belgium.