Hemp Production Considerations - and Diseases-

Scott Lukas Assistant Professor

Hermiston Agricultural Research & Extension Center What is hemp vs. marijuana? Cannabis sativa Hemp Marijuana

≤ 0.3% Total THC* > 0.3% Total THC*

* The first American flag made by Betsy Ross was made from industrial hemp 1777 Where are we with hemp 2019 Oregon production

• 63,000 registered acres in 2019, nearly six times more than in 2018 • 1,940 registered growers in the state • Most all of the crop is being grown for hemp essential oils with dependence on feminized seeds for production Expansive production and limited research, we are all learning at the same time.

1. Overview of pests that prey on or potentially may affect hemp

2. Diseases observed in 2019 hemp crops I will provide some management options but cannot list products or specific control options

Products are under development and approval

Research to support insect and disease control is underway Insects associated with hemp

Group I: Below soil

Group II: Leaf

Group III: Stem/stalk

Group IV: Flowers and seeds Wireworm

Pacific coast wireworm Limonius canus

Click beetle larvae Determine levels Bait stations Soil collection – sieve Soil inspection during tillage

Will weaken or kill plants from damage or secondary infection Wireworm

Pacific coast wireworm Life Cycle

Move upward in soil in spring - Overwinter at 12”-24” depth Wireworm Group II – Leaf feeders

Sucking and piercing Chewing (Leaf defoliators) Sucking & Piercing

Leafhoppers Spider Mites

Aphids

Thrips Russet Mites

CSU-W Cranshaw Cannabis aphid Phorodon cannabis Passerini • Feed on plant fluids • Winged and wingless • High populations lead to reduced growth, vigor, wilting, yellowing • Look for pest or excreted honeydew

CSU-W Cranshaw

• Piercing/sucking • Jump from plant to plant • Feeding sites on leaves and stems • Often times cannot see damage • Not a significant feeding issue • Confirmed vector of disease in hemp

CSU-W Cranshaw Beet Circulifer tenellus Baker

Beet curly top is transmitted to plants by the

Newly identified insect-vectored pathogen of hemp Hemp russet mite Aculops cannabicola Farkas • Usually on bottom of leaf • Can be on stems • Piercing to feed on cell fluid • Leave may appear dull in color • May see marginal leaf roll • Suppress leaf growth

Watch for high population in flowers Hemp russet mite Hemp russet mite??

CSU-W Cranshaw Chewing

Caterpillars Grasshoppers

Beetles Earwigs

CSU-W Cranshaw Defoliators

Yellowstriped armyworm Yellow woollybear Beet webworm Significant late season Minimal damage on leaf Minimal damage on leaf damage

Thistle caterpillar Beet armyworm Zebra caterpillar Minimal damage on leaf Minimal damage on leaf Minimal damage on leaf Damage worst late season in buds and seeds CSU-W Cranshaw Beetles

Leaf feeding

Generally not a concern

Adults present = larvae

Palestriped flea beetle

Southern corn rootworm adult and damage

Western black flea beetle Grasshoppers

Stem feeding seems to cause the most injury by grasshoppers

Looks like mechanical damage

Extremely mobile

CSU-W Cranshaw Group III – Stem / Stalk Borers Borers

European corn borer Ostrinia nubilalis ~2 generations /season Wide host range

Pre WWII era publications mention European corn borer

Entomology -UFL

CSU-W Cranshaw / Canadian Hemp Alliance Borers Eurasian hemp borer Grapholita delineana

Potential 3 generations Often feed on stem under flower buds

CSU-W Cranshaw Group IV – Flowers / Seeds Group IV – Seed / Flower

Stink bugs. (can also feed on leaves) Lygus bugs

CSU-W Cranshaw Group IV – Flower

Corn earworm Adult of corn earworm Helicoverpa zea Boddie Potential to cause significant damage to flowers. Late season pest Can be hidden within flower

CSU-W Cranshaw Group IV – Flower

CSU-W Cranshaw Precautions

Volunteers - can sustain significant numbers of pests between

seasons CSU-W Cranshaw Scouting /monitoring

Sticky traps Loupe Pitfall traps

Sweep nets Visually Pan traps

CSU-W Cranshaw Biological controls

With currently limited chemical options, consider biological control

Syrphid flies

Lady beetles Minute pirate bug Green lacewings

Predatory mites Spiders & other arachnids Predatory

CSU-W Cranshaw Products available to use now in Oregon

https://www.oregon.gov/ODA/programs/Pesticides/Pages/CannabisPesticides.aspx

Diseases observed in 2019

Material from HAREC Pathology Lab. Drs. Ken Frost, Hannah Rivedal Diseases observed in 2019

PNW Disease Management Handbook Pnwhandbooks.org

Hemp Diseases Not diseases observed in 2019

Abiotic and genetic abnormalities

Nitrogen Deficiency Herbicide Injury Genetic Disorder - Chimera Potential Diseases

Canker (Sclerotinia sclerotiorum)

Root rot, sore shin (Rhizoctonia solani)

Brown rot of buds (Alternaria alternata)

Gray Mold (Botrytis cinerea)

Stem canker Be cautious of soil excess soil (Scleotinia sclerotiorum) moisture & moisture on crop canopy Promote airflow Diseases observed in 2019 Often times a complex of pathogens Pythium spp.

Damping off Wilt Root rot

Mid-season Pythium wilt Pre-plant soil test for pathogen suite! Diseases observed in 2019

Virus / viroid

Sunn-hemp mosaic virus

Beet curly top virus

Tomato ringspot virus Hop latent viroid virus Y Focal diseases

1. Fusarium root and crown rot

2. Beet curly top Focal diseases

Fusarium root and crown rot symptoms

• Soil borne

• Stunting

• Poor root system development

• Red, brown, or black crown or root lesions

• Vascular discoloration

• Early wilting, premature flowering, or death

• Peak in early to mid-August Focal diseases

Fusarium root and crown rot management

• Crop Rotation • Cultural Methods • Soil fertility management • Plant certified clean seed (Soil or seed transmitted) • Slight deficit irrigation early season • Reduce water stress at flowering • Promote the breakdown/removal of crop debris Focal diseases

Beet Curly Top Virus • Not mechanically or seed transmitted • Vectored by beet leafhopper • Vector and virus have a broad host range (Vegetables, annual flowers, hemp)

Beet leafhopper Focal diseases

Beet Curly Top Virus Symptoms

• Downward curling or cupping of leaves • Leaf distortion and puckering • Leaf yellowing • Thick, brittle leaves • Stunting • Reduced yield • Plant death Focal diseases

Beet Curly Top Virus Management

• Curly top has a broad crop host range

• Monitor insect populations

• Remove affected plants if possible Russian Thistle • Partial shading and/or floating row covers discourage the leafhopper vector from moving onto plants

• Remove weed leafhopper hosts • Russian thistle (summer) • Tumble mustard, Filaree (winter)

Tumble mustard and Filaree Disease ID Test, don’t guess! Diagnostic clinics can provide results that inform management decisions

OSU HAREC Plant Clinic Acknowledgements

Whitney Cranshaw Silvia Rondon

Kenneth Frost & Hannah Rivedal QUESTIONS?

[email protected] 541-656-8090