Potato virus Y (PVY) in Cannabis – Mosaic Symptoms, Aphid Transmission and Prevention

Overview

Potato virus Y (PVY) is one of the most significant plant viruses globally and is well-known in potato and tobacco cultivation. Recently, PVY has also become relevant in cannabis cultivation, as studies show that PVY can be efficiently transmitted to cannabis by hemp aphids—potentially affecting growth and flower quality.

General Information

Name: Potato virus Y (PVY)
Taxonomy: Family Potyviridae, Genus Potyvirus
Genome: Positive-sense single-stranded RNA (ssRNA+)
Host range: Broad, including potato, pepper, tobacco, tomato, and Cannabis sativa

Modes of Transmission

Primary Transmission:

Aphids in non-persistent mode
A single short feeding by an infected aphid can transmit the virus.

Relevant Aphid Species:

Phorodon cannabis (hemp aphid) – highly efficient
Myzus persicae (green peach aphid)
Other aphid species from mixed gardens (chili, tomato, etc.)

Additional Routes:

Mechanical: Possible via contaminated tools or hands, though less common.
No seed transmission: Not demonstrated in Cannabis.

Symptoms in Cannabis

Vegetative Phase:

Light mosaic-like patterns on younger leaves
Mild speckling or mottling
Slight leaf curling or rippling
General growth reduction in sensitive strains

Flowering Phase:

Less upper leaf mass
Delayed or impaired flower development
Smaller buds, possible reduced trichome density
Not typical “dudding,” but reduced quality in severe cases

Diagnosis

Visual Inspection:

Symptoms are often mild and can be mistaken for nutrient deficiencies or light stress.

Laboratory Testing:

ELISA test kits (protein-based) – reliable and readily available
RT-PCR – more sensitive, especially for low viral loads
Rapid tests: PVY ImmunoStrips are widely available (commonly used in potato farming)

Importance for Home Growers

PVY poses a commonly overlooked risk for home growers. Aphids can transmit PVY from garden vegetables (e.g., peppers, tomatoes, spinach) to cannabis. Both indoor and outdoor grows can be affected—even when no obvious symptoms appear.

Once introduced, PVY often spreads silently through multiple plants because symptoms are so mild.

Prevention and Management

1. Vector Control

Yellow sticky traps for early aphid detection
Beneficial insects (e.g., ladybugs, lacewing larvae)
Use neem oil or insecticidal soaps regularly
Quarantine new plants for at least 2 weeks

2. Hygiene Practices

Disinfect tools after each plant
Wash hands and change clothes when moving between crops

3. Plant Material

Avoid cuttings from unverified sources
Use seeds from healthy mother plants (even if PVY isn’t seed-borne)

Treatment Options

There is no cure for PVY-infected plants. The virus persists systemically and cannot be chemically eliminated. Affected plants should be isolated or removed to prevent further spread. True virus elimination is only possible via meristem tissue culture—not feasible for hobby growers.