Improve Yields With Dark Heart HpLVd Screening

improve yields with dark heart hplvd screening

510-394-9515 for service

Executive Summary“Dudding” is a common disease of cannabis plants, occurring throughout North America. Dark Heart Nursery (DHN) has shown that this disease is caused by the Hop Latent Viroid (HpLVd). Removing this stubborn disease from your crop can greatly improve the yield and quality of your grow.

Sanitation is the key to preventing the spread of the viroid, but it may not be enough. Genetic screening for the viroid through DHN can verify that a mother block or a crucial strain are disease-free.

If an infected plant absolutely must be saved, then DHN provides a patented remediation process through pre-treatment and meristem tissue culture. This process is not inexpensive, but it may be worthwhile in order to save a strain that would otherwise be lost.

In addition, DHN offers certified clean stock in 31 cannabis strains that can be used to build or rebuild a mother block and give your crop a clean start.

improve yields with dark heart hplvd screening

510-394-9515 for service

Most cannabis growers have experienced “dudding.” Plants are stunted, the leaves smaller and spiky. The nodes are closer together. In the flower stage the buds are smaller and looser, with fewer trichomes on all parts of the plant. The rich scent of fresh cannabis is reduced (Fig. 1).

Dudding is a stubborn problem. It usually affects only some of the plants in a grow, and normal antifungals

and pesticides have no effect on it. It leads to lost plants, reduced yield, and loss of cannabinoids and flavor in any plants that can be saved.

For some time the cause of this disease was not well-understood, but in 2019 researchers at Dark Heart Nursery identified the pathogen: Hop Latent Viroid (HpLVd).

Introduction

Figure 1. These two plants are the same age and strain

infected healthy

improve yields with dark heart hplvd screening

510-394-9515 for service

transmitted rarely in seeds (about 10%). DHN has confirmed seed transmission in cannabis but is still working to determine transmission rate.

Currently HpLVd is very widespread. DHN has found infected plants in every grow it's tested throughout the United States. If you have dudding in your grow, then you may have HpLVd. Unfortunately, merely destroying the plants that show symptoms won’t eliminate your problem, since infected plants do not always show symptoms.

what is a viroid?From the name, a viroid sounds similar to a virus, but the two are fairly different. A virus is a small package of DNA or RNA wrapped in a protein shell called a capsid. The virus invades a cell and takes over the cell’s machinery to turn it into a virus factory.

A viroid is the simplest disease agent known at present. They are much smaller and simpler even than viruses. A viroid is nothing more than a small loop of RNA without the protective capsid (Fig. 2). They reproduce by invading a cell and taking control of RNA polymerase II, an enzyme that the viroids use to copy themselves. All currently known viroids are plant pathogens.

Hop latent viroid was first identified in hop plants in 1988. Cannabis is closely related to hops, and HpLVd infects it as well. In fact, the effects of the disease are even more serious in cannabis.

Hop Latent Viroid spreads mainly on tools or by touch: a tool that is used to prune an infected plant or a glove that touches a break in the plant’s skin can then transmit the viroid to another plant that is cut or handled in the same way.

It can also spread by cloning. If you take a clone from an infected area of the plant (the virus is not distributed evenly in the plant) then the new plant will also be infected. In hops HpLVd has also been

Controlling HpLVd

DHN has found infected plants in every grow it's tested throughout the United States.

Figure 2. Viroid size chart

improve yields with dark heart hplvd screening

510-394-9515 for service

prevention is keyThe key is sanitation. You must act as though every plant in your grow is infected. The methods are similar to sanitation to prevent the spread of Botrytis or powdery mildew.

• If any plant shows symptoms of dudding,immediately remove it from the grow area. Suchplants should be destroyed unless they are part of acrucial strain or otherwise critical to your business.In this case, see below for possible remediation.

• If you have multiple fields or grow rooms, thendedicate a set of cultivation tools for use only ineach one.

• Likewise, have a dedicated coat or apron for eachgrow area.

• Use disposable gloves for handling the plants.Change gloves after each plant.

• Within a given room or field, sanitize your toolsbefore beginning work and again after each plantthat you work on. Use a sanitizing agent such asbleach or Virkon (alcohol is not effective) and followthe manufacturer’s instructions for sanitizinggardening tools.

prevention may not be enoughSanitation is the cornerstone of the fight against HpLVd, but it may not be enough. The viroid spreads so easily that even a small mistake in a sanitation protocol can lead to infection. The surest approach is to find and eliminate the viroid from your stock.

The surest approach is to find and eliminate the viroid from your stock.

Figure 3. Infected (top) vs. healthy (bottom) plants

infected

healthy

improve yields with dark heart hplvd screening

510-394-9515 for service

Note that DHN has already produced many viroid-free cannabis strains, so consider this option only if the one you need to save is not already in our stock.

certified clean stockBefore being placed in Dark Heart's nursery, new plants are quarantined, then screened three times. Any plants that test positive are put through pretreatment and meristem tissue culture before they are transferred to the nursery. In addition, DHN performs ongoing testing of nursery plants and any infected plants are removed and destroyed.

Using these rigorous protocols, DHN has eliminated HpLVd from 31 cannabis varietals. We offer disease-free stock that can be used to create a mother block or replace diseased plants that were removed from the mother block after screening.

Dark Heart’s Solution

Figure 4. Infected (left) vs. healthy (right) plants

Dark Heart Nursery offers a solution to HpLVd on three levels: Screening, remediation, and certified clean stock.

genetic screeningThe only way to know for sure if a plant is infected is a genetic screen such as the one offered by Dark Heart Nursery. DHN will collect samples from your plants and test them with qRT-PCR to detect even small levels of viroid infection.

DHN has eliminated HpLVd from 31 cannabis varietals.

Because the viroid is not evenly distributed throughout the plant, it's necessary to get a negative result on tests of three different samples from a plant to rule that plant viroid-free. Since any plant could be infected, only screened plants can be considered completely safe. It is not practical to test every plant in a main grow, but genetic screening is useful to clean up and certify your mother block.

remediationIf you have an infection problem serious enough that you stand to lose an entire strain, then it may be worthwhile to consider remediation. DHN uses a patent pending pre-treatment process followed by meristem tissue culture to produce a clean, disease-free plant from an infected plant.

improve yields with dark heart hplvd screening

510-394-9515 for service

Improve Your GrowScreening, remediation, and clean stock can combine to give you a disease-free mother block that can then be used to clone clean plants for your main grow. Proper sanitation can then keep your grow clean.

By eliminating HpLVd from your grow you can improve your overall yield, potency and flavor profile. You can simplify your production and avoid the waste of destroying infected plants. You reduce your costs and get a better product that leads to higher returns.

SummaryDudding in cannabis leads to reduced yields and lower profits. Dudding is caused by a highly contagious pathogen that is immune to standard treatments. If found in a mother block, and left untreated, the Hop Latent Viroid will persist through one crop after another.

The technology and services offered by Dark Heart Nursery can eliminate HpLVd from your grows and prevent it from gaining a foothold again.

For more information on how DHN can help you with your dudding problem, fill out a contact form at darkheartnursery.com/contact-us.

510-394-9515 for service

Dark Heart TeamDr. Jeremy Warren is an experienced plant pathologist with over 20 years of diagnosing and curing plant health issues. He received his PhD from University of California, Davis. His research at Dark Heart's tissue culture lab led to the first positive identification of the hop-latent viroid. He is passionate about helping cultivators succeed by helping them grow healthy plants that improve crop yields.

Left: Director of Plant Health Jeremy Warren