Lettuce Chlorosis Virus in Cannabis

Lettuce chlorosis virus (LCV) is a linear, single-stranded positive-sense RNA virus and a member of the Crinivirus family. LCV is commonly found in lettuce grown in Southern California deserts, but it is believed to have a wide host range that includes cannabis and hemp plants.

How does Lettuce Chlorosis Virus affect Cannabis and Hemp Plants?

Cannabis and hemp plants that are infected early will have stunted growth, but may not show visual signs until a few weeks into flowering. Those visual signs of LCV infection include yellow, rolling, brittle leaves. While the infection does not kill cannabis and hemp plants, it significantly affects yield. Plant will produce smaller flowers with fewer trichomes, cannabinoids, and terpenes. 

How does Lettuce Chlorosis Virus spread?

Studies have shown that LCV can be transmitted from plant to plant via pests, specifically the whitefly. There have also been claims that the virus can be transmitted via water. 

More commonly, LCV can is spread through cloning when cuttings are taken from an infected mother. And because symptoms of LCV often present in the flowering stage, it can be hard to identify infected mother plants. This is especially true when infection occurs later in the plant’s development, since stunted growth will not be as apparent. 

How can Lettuce Chlorosis Virus be Controlled?

Once a cannabis or hemp plant is infected with LCV, it can only be eliminated from the plant via tissue culture. Cultivators should screen mother plants with qPCR tests to make sure any cuttings that are taken will be virus free. If the mother does have LCV, cultivators can use tissue culture to eliminate the virus and produce a new, healthy mother. Cultivators can also screen incoming clones with qPCR assays to make sure they are not introducing infected plants to their grow.