Surveying for Potential Diseases and Abiotic Disorders of Industrial Hemp (Cannabis sativa) Production

Abstract

Industrial hemp (Cannabis sativa L.) has recently been reintroduced as an agricultural commodity in the United States, and, through state-led pilot programs, growers and researchers have been investigating production strategies. Diseases and disorders of industrial hemp in the United States are largely unknowns because record-keeping and taxonomy have improved dramatically in the last several decades. In 2016, North Carolina launched a pilot program to investigate industrial hemp, and diseases and abiotic disorders were surveyed in 2017 and 2018. Producers, consultants, and agricultural extension agents submitted samples to the North Carolina Department of Agriculture and Consumer Services Agronomic Services Division (n = 572) and the North Carolina Plant Disease and Insect Clinic (n = 117). Common field diseases found included Fusarium foliar and flower blights (Fusarium graminearum), Fusarium wilt (Fusarium oxysporum), and Helminthosporium leaf spot (Exserohilum rostratum). Greenhouse diseases were primarily caused by Pythium spp. and Botrytis cinerea. Common environmental disorders were attributed to excessive rainfall flooding roots and poor root development of transplanted clones.

The bud rot pathogens infecting cannabis (Cannabis sativa L., marijuana) inflorescences: symptomology, species identification, pathogenicity and biological control

“…The most common pathogen associated with bud rot symptoms on cannabis and hemp grown indoors and outdoors, respectively, in British Columbia was B. cinerea, representing 88% of 178 isolates recovered from 10 sampling sites over 2 years of study. This confirms previous findings associating B. cinerea with bud rot symptoms (McPartland 1996;McPartland et al 2000;Punja et al 2019;Garfinkel 2020;Jerushalmi et al 2020;Thiessen et al 2020). Diseased samples with B. cinerea were recovered most frequently during September-February, months represented by cooler night temperatures and wet or humid daytime conditions, both of which are known to favour infection by B. cinerea on other crops (Jarvis 1962;Bika et al 2021).…”

“…Growth and sporulation of the biocontrol fungi on the inflorescences, as observed under the scanning electron microscope, was prolific, indicating they were well established within 48 h. Applications made 24 h prior to, or 24 h after pathogen inoculation, had no suppressive effect (authors, unpublished observations). Previous research with G. roseum (Clonostachys rosea) has demonstrated its efficacy and utility against a number of pathogens, including B. cinerea, on a range of crops (Sutton et al 1997;Chatterton and Punja 2010;Sun et al 2021). The various modes of action described for Trichoderma, Gliocladium and Bacillus against B. cinerea and other pathogens (Sutton et al 1997;McPartland et al 2000;Benítez et al 2004;Haidar et al 2016;Nicot et al 2016;Samaras et al 2020;Sood et al 2020;Sun et al 2021) are likely taking place against Botrytis bud rot but further studies are needed.…”

“…Previous research with G. roseum (Clonostachys rosea) has demonstrated its efficacy and utility against a number of pathogens, including B. cinerea, on a range of crops (Sutton et al 1997;Chatterton and Punja 2010;Sun et al 2021). The various modes of action described for Trichoderma, Gliocladium and Bacillus against B. cinerea and other pathogens (Sutton et al 1997;McPartland et al 2000;Benítez et al 2004;Haidar et al 2016;Nicot et al 2016;Samaras et al 2020;Sood et al 2020;Sun et al 2021) are likely taking place against Botrytis bud rot but further studies are needed. The timing of application of these biocontrol products needs to be evaluated on whole plants to ensure they are established prior to the penultimate 2-3 weeks before harvest when disease symptoms become apparent.…”

Morphometric relationships and their contribution to biomass and cannabinoid yield in hybrids of hemp (Cannabis sativa)

“…Biotic and abiotic factors can influence hemp yield, uniformity, and stability (Thiessen et al ., 2020). One of the most significant diseases of hemp in the northeastern US, hemp powdery mildew (PM) is caused by the obligate biotrophic fungal pathogen Golovinomyces spadiceus (Szarka et al ., 2019; Weldon et al ., 2019), and can lead to early leaf drop and reduced inflorescence quality (Punja et al ., 2019; Stack et al ., 2021).…”

Pathogenicity and Mefenoxam Sensitivity of Pythium, Globisporangium, and Fusarium Isolates From Coconut Coir and Rockwool in Marijuana (Cannabis sativa L.) Production

“…and Fusarium spp. have been reported in Kentucky, Indiana, Israel, California, Canada, Italy, and North Carolina (Beckerman et al, 2017(Beckerman et al, , 2018Sorrentino et al, 2019;Jerushalmi et al, 2020;Thiessen et al, 2020;Pitman et al, 2021). Pythium spp.…”