Bio/Microbial Analysis

How do I interpret my bio-test results?

READING AND INTERPRETING TEST RESULTS – BIOLOGICAL / PHYSIOLOGICAL ANALYSIS OF PLANT MATERIAL

 PHYSIOLOGICAL STATE OF TRICHOMES:

Table 1. Color of trichome gland heads on a single sample (clear vs. milky).

Table 2. Color of trichome gland heads on a single sample (amber)

Table 3. Amount of damaged or degrading trichomes on a single sample

Table 4. Amount of reduced / stunted / sessile trichomes on a single sample.

IMPURITIES AND FOREIGN CONTAMINANTS:

Table 5. Severity index for sporulating hyphae, mycelia, and mildew (qualitative analysis)

FUNGI:

Mold: A fungus that grows in the form of multi-cellular filaments called hyphae.

Hyphae: The long, branched, filamentous structures of fungi. A collective growth of hyphae from a given fungus is known as the mycelium or mycelial mat. Hyphae allow for the vegetative growth and spread of a fungus. Some species, when sporulating, can be harmful for human consumption / inhalation. The most common causes of fungi on a plant are; high humidity, exposure to UV radiation which stimulates sporulating during the curing process, improper management techniques such as forgetting to sanitize tools, and improper air-flow during both the growth and curing process.

Sporulating: Spores are the primary mode of dispersal in fungi. In sporulating fungi, the spores grow directly from the hyphae and wait to be spread through contact with a carrier (such a human or animal) or through air circulation.

Mildew: In horticulture, the term mildew refers to a species of fungus belonging to the order Erisiphales, or a group of fungus-like organisms in the family Peronosporaceae. Mildew typically presents itself as a powdery, often whitish growth consisting of small, threadlike hyphae – and are typically produced on the leaves of living plants. Two main species of mildew are common in Michigan, the first being Powdery mildew and the second being downy mildew.

Powdery Mildew: Belonging to the order Erisiphales, which is an Ascomycete fungi. These species have superficial mycelium that act to extract nutrients from the host plant through specialized hyphae that penetrate the epidermis of the plant. The infection of the host plant begins with the sexual ascospores or the asexual conidia that germinate on the surface of the plant leaf or stem. With most powdery mildews, only the epidermal cells of the plant are attacked. The external mycelium give rise to short conidiophores, each of which bear a row of spores which can easily become detached and dispersed through air currents, resulting in new infections. Most powdery mildew infections germinate in the spring, though with indoor gardening practices, they can be present year round.

Downy Mildew: Belonging to the family Peronosporaceae and referring to several types of oomycete microbes (or water molds) that are obligate parasites of plants, meaning that they must parasitize plants in order to grow and complete their life-cycle. Again, these microbes typically parasitize their host as intercellular mycelium using haustoria to puncture the epidermis and gain entry to the host plant. Downy mildews reproduce asexually by forming sporangia atop white sporangiophores located on the lower surface of infected leaves and are disseminated through the air, however some sporangia may germinate by forming zoospores or a germ-tube which may then be transmitted through water.  The best way to avoid downy mildews is to ensure that any grow space remains clean and that no resting water is allowed to sit on or around plants. 

Table 6. Infestation severity index for the two spotted spider mite (adapted from McPartland et al)

Spider Mites: (Family: Tetranychidacea):  Arachnid pests common to Cannabis crops. Indoor areas are typically contaminated by bringing in clones from infested mother plants, and outdoor crops are reportedly contaminated most frequently and at greater severity in warm climates and can result in significant crop loss. Spider mites usually congregate on the underside of leaves, though heavy infestation may result in mites on any portion of the plant. Spider mites tend to infest crops with a “patchy” distribution pattern; therefore early infestations may be overlooked.  Symptoms of spider mite infestation are often the worst during flowering – where shortened light cycles may induce diapause in the spider mites, causing them to cluster together at the very tips of leaves and tops of flowering plants.  The two spotted spider mite can hatch in as little as 3 days and become sexually mature in as little as 5 days. Due to this accelerated rate of reproduction, spider mites are able to adapt quickly and develop resistance to pesticides, so chemical control methods can become less effective when the same pesticide is used for one location over an extended period of time.

To learn more, visit http://entnemdept.ufl.edu/creatures/orn/twospotted_mite.htm

Predator Mites: (Family: Phytoseiidae): Predatory mites are commonly used to control spider mite populations and can be very effective in eliminating pests in a garden, however when the pest population has been consumed, these mites starve and subsequently die on the flower. The adult females are reddish in color and can consume between 5-7 adult spider mites or approximately 20 spider mite eggs in a day.

To learn more, visit http://www.ipm.ucdavis.edu/PMG/NE/phytoseiulus_persimilis.html

Table 7. Infestation severity index for Russet Mites

Russet Mites: (Family: Eriophyidae): Also known as rust mites or thistle mites. These mites are becoming increasingly common in Michigan. The russet mite is often white, pink or tan and given their minute size can be easily distinguished from spider mites, but may be hard to identify with the naked eye. The hemp russet mite (A. cannabicola) feeds primarily on leaf petioles and  leaflets, feeding causes leaflets to curl at the edges and followed by the leaf tissue turning chlorotic and then necrotic. These mites are capable of infesting by the thousands, infesting flowering tops and then selectively feeding upon the pistils, leaving a female flower completely sterile.  Outdoor, these pests are thought to overwinter on seeds, roots or root buds. Indoor, the populations are capable of living on the plants year round. Russet mites begin at the bottom of a plant and move upward as the plant dies below the infestation and spread to other plants by wind or splashing water. The life cycle takes approximately 30 days under optimum conditions of 27 C and 70% relative humidity.

Table 8. Infestation severity index for thrips  (adapted from McPartland et al)

Thrips:  (Order: Thysanoptera): Immature and adult thrips puncture plant surfaces and suck up leaf sap, giving rise to symptoms of white specks or occasionally streaks. It is important to know that while adult thrips do have wings, they are more likely to use jumping as a mode of dissemination. Thrips typically begin on the underside of leaves or tucked within flowers. Infested plants become ridden with tiny black specks of thrip feces and dead and decaying bodies. Thrips damage can be distinguished from spider mite damage in that thrips leave irregularly shaped lesions on the underside of leaves, typically filling in the spaces between leaf veins, whereas spider mites cause small white lesions on the upper side of leaves.

Table 9. Infestation severity index for aphids  (adapted from McPartland et al)

Aphids:  (Family: Aphididae): Aphids suck sap from a plants vascular system to steal sugar, nutrients, or water from through the use of long narrow stylets. Aphids can cause significant damage to a plant on its own, but is also known to damage plants by serving as a vector for fungi, bacteria, and plant viruses. Aphid damage typically increases in warm, moist weather with light rain and some wind.  Aphids are typically weak fliers but can use drafts of wind to move around. The first symptoms one might notice after an aphid infestation are wilting and yellowing of plant leaf tissue that can be confused with damage caused by spider mites or white flies.

Other common invertebrate pests:

White Flies: (Family: Aleyrodidae): White flies are typically a problem in warm indoor gardens and are related to aphids or leafhoppers, damaging plants by sucking sap from the living tissues and vectoring plant viruses. White fly damage is characterized by a loss of plant health, yellowing, or wilting leaves. Leaves will initially become glazed with a sticky sap or honeydew which promotes the growth of a brown fungus that colonizes these sticky patches. If you look closely at the underside of leaves you may see the adults that look like bits of ash. The females lay eggs on the underside of leaves near the tops of flowering plants, often clustered into a familiar circular pattern anchored by short stalks anchored into the leaf stomata.  Optimal conditions are around 27 C and between 75-50% relative humidity.

Fungal Gnats:  (Family: Mycetophilidae and Sciaridae): The larvae of fungus gnats infests plant roots close to the soil surface. Infested plants may lose vigor and color. The fungus gnat is also capable of chewing and wounding root tissue which may allow for the infection of the plant by soil borne fungi. Fungus gnat larvae attacks plants that are stressed by nutrient imbalance and thrive in waterlogged soil but prefer to feed on decaying vegetation and fungus in the damp soil. The adults do not feed on plants and “infestations” are typically minor and limited to a few unfortunate adults that got stuck in the sticky trichomes of the plant.

MINOR IMPURITIES:

Anthers: Oval or “banana shaped” plant structures, typically located at the terminal part of the stamen, and contain pollen. Anthers are associated with male flowers.

Stamen: The male fertilizing organ of a flower, typically consisting of the pollen-containing anther and the attached filament.

Detritus: Organic debris such as dirt.

Fibers: Any natural or synthetic fibers from a foreign source. Very frequent on flower samples (>90%). Most frequently, the fibers we see are from clothing, smart pots, carpet, etc. and may be invisible to the naked eye.

Hair: Any naturally occurring pet or human hair. Under a microscope, these are easily discernible from fibers given their more natural color and a more natural looking growth habit.

Mature Seeds: Seeds developed from the ovary of a female flower that has been pollinated. Mature seeds are entire and intact and may alter the flavor profile of a flower when burned.

Premature Seeds: Seeds that began to develop from the ovary of a female flower, but did not develop fully prior to senescence of the plant. Premature seeds may alter the flavor profile of a flower when burned.