Disease Management for Propagation in Nurseries
Alan Windham, Professor, Plant Pathology Best Practices for Propagation
Start with disease free plant material
Keep cuttings stress free
Keep propagation areas and cutting instruments as clean as possible
Limit access to propagation areas
Use disinfectants properly
Avoid contamination of clean cuttings, flats, trays, etc
Train employees to recognize disease problems Train Employees to Recognize Problems Educate your employees
Post information about problem diseases where employees gather. Start with Disease Free Plant Material Take cuttings from plants free of disease Taking cuttings from diseased plants can be disastrous Do you know the symptoms of boxwood blight? Propagate in-house
Canna Yellow Mottle Virus
Many viral diseases are spread by propagating diseased plants Hosta ‘August Moon’
HVX The hosta on the left is healthy; the one on the right is infected with hosta virus x Hosta virus x on ipmimages.org
Websites such as ipmimages.org have images of diseases, insects, weeds, etc Foliar Nematode/Brunnera
Foliar nematodes are spread by propagating infected plants;also, by splash Dispersal during irrigation or rain events. Discard infested plants. Foliar nematode emerging from leaf tissue Crown Rot of Liriope
Phytophthora or Fusarium are capable of causing crown rot of liriope. Daylily Rust
Daylily rust doesn’t usually overwinter successfully in zones 6-7; inspect plants Carefully when they arrive at your nursery. Phytophthora root rot – roots die, and foliar symptoms show up later
Phytophthora root rot symptoms on boxwood. Dead roots = dead foliage. Monitor root health throughout the production cycle. Phytophthora root rot/Juniper ‘Blue Pacific’?
Juniper ‘Blue Pacific’ is very susceptible to phytophthora root rot. DIY Phytophthora detection with a lateral flow kit
Root, stem or leaf tissue can be assayed. Results are available within minutes. Black Root Rot (Thielaviopsis)
Ilex crenata ‘Hoogendorn’ exhibiting chlorotic foliage associated with black root rot Black Root Rot/Ilex crenata
Ilex crenata ‘Soft Touch’ Blackened root tips due to Thielaviopsis infection Early symptoms of Black Root Rot
Not all root rot symptoms are visible with the naked eye. Root symptoms of black root rot
Ilex crenata ‘Sky Pencil’ Thielaviopsis (Black Root Rot)
Chlamydospores of Thielaviopsis in pansy root tissue. Black root rot of holly often starts in propagation Black Root Rot?
How do you determine if a plant is infected? Carrot Assay for Black Root Rot
Wash roots and blot dry. Place roots on carrot discs in a food storage container with a moist paper towel. Cover and incubate at room temperature for 7 days. Assay for black root rot – Day 1 Carrot Assay for black root rot – Day 7
Thielaviopsis grew out of infected root tissue and is sporulating on the carrot discs. Keys Disease Management
Propagate – take cuttings, divisions from healthy plants Index, assay stock plants for presence of disease Keep Propagation Areas as Clean as Possible Avoid Contamination Raised propagation beds prevent soil contamination Drip irrigation to keep foliage dry and minimize foliar diseases Keep Propagation Areas as Clean as Possible Footbath to prevent pathogens from entering propagation area
Keep hose nozzle off the ground Pasteurizing media with aerated steam Further Reading:
Diseases of Woody Ornamentals and Trees in Nurseries. 2001. APS Press Safe Procurement and Production Manual. 2012. Oregon Association of Nurseries. http://www.oan.org/displaycommon.cfm?an=1&subarticlenb r=861 Soil, Plant and Pest Center http://soilplantandpest.utk.edu/ Soil, Plant and Pest Center Facebook Page https://www.facebook.com/SoilPlantPestC enter Phytophthora Online Course http://oregonstate.edu/instruct/dce/phyt ophthora/