Hemp Production Considerations -Insects 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 insect 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 Leafhoppers
• 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 leafhopper Circulifer tenellus Baker
Beet curly top virus is transmitted to plants by the beet leafhopper
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 Hemiptera
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 Potato 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