Beauveria bassiana is an entomopathogenic fungus: it infects and kills insects. Spores that land on an insect germinate, grow through the cuticle and multiply inside the body. Dead insects turn stiff and become covered in white fungal growth, which is why the disease is called white muscardine. It is found naturally in soils worldwide.
In practice
Growers apply spore formulations as foliar sprays against whiteflies, thrips and aphids, or as drenches against root aphids and other soil pests. Spores need direct contact with the pest and benefit from high humidity for the first hours after application; very dry air and some fungicides reduce efficacy. It works over days, not hours, so it is used early and repeated. Because it adds live fungal spores, growers generally keep it off flowering buds, where it could raise microbial counts on lab tests. Check what is registered for cannabis locally and what the label allows by growth stage.
Don't confuse with
- Botrytis: a plant pathogen that rots buds; Beauveria attacks insects, not plants.
- Bacillus thuringiensis: a bacterium that must be eaten.
- Metarhizium: a related insect-killing fungus with green spores.
Germination is the stage where a viable seed absorbs water, splits its shell and pushes out a root (radicle), usually within 1-7 days at 20-30 °C.Foliar feeding is spraying a dilute nutrient solution onto leaves for quick uptake through the leaf surface; it suits micronutrient fixes but cannot replace root feeding.Small white-winged sap-sucking insects of the family Aleyrodidae, mainly Trialeurodes vaporariorum and Bemisia tabaci, that fly up when disturbed and coat leaves in honeydew.Small soft-bodied sap-sucking insects of the family Aphididae that cluster on stems and leaf undersides, excrete sticky honeydew and multiply rapidly by live birth.Aphids that colonise roots and the crown below the medium surface, on cannabis chiefly the rice root aphid (Rhopalosiphum rufiabdominale), causing slow, unexplained decline.Photon efficacy is how many micromoles of PAR photons a fixture produces per joule of electricity (µmol/J); higher means more light for the same power bill and heat.Botrytis cinerea, the fungus behind bud rot or grey mould, which rots dense colas from the inside in cool, humid conditions late in flower.A soil bacterium whose crystal proteins kill caterpillars after they eat treated leaves; subspecies kurstaki and aizawai are the strains used against budworms.Slender insects about 1-2 mm long, chiefly western flower thrips (Frankliniella occidentalis), that rasp leaf surfaces, leaving silvery streaks dotted with black frass.Using living natural enemies, such as predators, parasitoids, nematodes and microbes, to suppress pests and diseases instead of, or before, chemical sprays.Contact products act only where the spray touches the pest; systemic products are absorbed and move inside the plant, which raises residue concerns in cannabis.
