Headshot of Punya Nachappa

Punya Nachappa, PhD
Associate Professor
Colorado State University
SPEAKER
CULTIVATION

Biology and Management of Hop Latent Viroid

Hop latent viroid (HLVd) is an emerging pathogen affecting hemp with potential to cause significant damage and crop loss. Since its initial detection in California in 2019, HLVd has been detected in all major hemp growing states including Colorado, Oregon, Washington and in Canada. There is limited information on the impact of HLVd on hemp biomass and yield whereas there is accumulating evidence that HLVd reduces cannabinoid levels in cannabis. HLVd is known to be transmitted mechanically to plants, however there is little information known about other transmission routes including possible arthropod vectors.

Here, we investigated the impact of HLVd on hemp biomass, inflorescence, seed yield and cannabinoid levels, the ability of hemp pests, cannabis aphids and wester flower thrips to transmit HLVd, and the effect of chemical elicitors in reducing HLVd infection levels. HLVd did not have an impact on hemp biomass and yield, but it decreased levels of certain cannabinoids such as THC. We found that cannabis aphids and thrips are able to acquire HLVd as soon as 5 minutes and maintain HLVd for several hours. Transmission assay results indicate cannabis aphids and thrips were able to transmit HLVd in hemp at a low percentage (24% and 14%, respectively). Certain chemical elicitors showed significant reduction in viroid titers compared to control treatments. Beyond potential viroid reduction, chemical elicitors such as salicylic acid, brassinolides (BR), and 6-benzylaminopurine (BAP) significantly increased biomass and flower production. However, SA, BR, TRIA, chlormequat chloride (CCC), and methyl jasmonate (MeJA) also reduced key cannabinoid levels, notably THC and CBD, highlighting the complexity of using chemical elicitors to control HLVd. Overall, this research developed new knowledge regarding HLVd, in an effort to manage and reduce losses to the hemp and cannabis industry in the U.S and worldwide.

Learning Objectives:

  • Assess the impact of HLVd on hemp yield and cannabinoids

  • Compare HLVd acquisition and transmission by two major cannabis pests, cannabis aphids and thrips

  • Evaluate the efficacy of various chemical elicitors in reducing HLVd infection
BIO
Punya Nachappa received her BS in agriculture from University of Agricultural Sciences in India. She obtained a MS degree in entomology from University of Georgia, and PhD in entomology from Kansas State University. After completing her PhD, she was a post-doctoral researcher at K-State and Texas A & M University. She was an Associate Professor at Purdue University Fort Wayne before joining Colorado State University (CSU). Currently, she is an Associate professor at CSU in the Department of Agricultural Biology. Her research program focuses on understanding the interactions between plants and insect vectors to manage plant pests and diseases in hemp. She has a dynamic lab group with 2 post-docs, 2 Research Associates, 3 PhD students,3 MS students and several undergraduate students. Her research is funded by USDA NIFA, FFAR, Institute of Cannabis Research and commodity groups.

ATTENDANCE IS LIMITED. THE OPPORTUNITIES ARE NOT.

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