June 24, 2017

Howard Schwartz – CO State Commentary – Onion ipmPIPE

CO Commentary (08-09-13)


COLORADO Commentary

Onion Crop Growth Stage and Status Last Modified: 08/09/13

Bulbing stages continue to develop normally in transplanted and seeded onions throughout the onion regions in the state.

Weather Impacts (temperature, rain, hail, freezing) Last Modified: 08/09/13

Severe storm damage affected many onion fields in northern Colorado, causing 50 to 75% defoliation with evidence of bulb rots beginning to develop within 7 to 10 days later.

Temperature Outlook* [2 – 4 weeks]: Above Normal

Precipitation Outlook* [2 – 4 weeks]: Below Normal

*Courtesy of Planalytics, Inc.

Insect Scouting, Outlook and Management Last Modified: 08/09/13


Thrips numbers range between 25 to 50 per plant in most production regions of Colorado; while the numbers are beginning to fall in fields approaching maturity.


No reports at this time


No reports at this time

Disease Scouting, Outlook and Management Last Modified: 08/09/13

Iris yellow spot virus

Scattered positive reports with ELISA or PCR testing, but no serious outbreaks reported yet.

Soil-borne Diseases (Damping Off, Pink Root, Fusarium)

Pink root and Fusarium basal rot apparent in some fields with a history of the disease.

Fungal Diseases (purple blotch, downy mildew, Botrytis)

No reports at this time

Bacterial Diseases (Xanthomonas, center rot, soft rots)

No reports at this time State Contact for Project Howard Schwartz Professor of Plant Pathology Colorado State University Email:howard.schwartz@colostate.edu

Collaborators: Whitney Cranshaw, Ned Tisserat, Stephanie Szostek, Janet Hardin,

Mike Bartolo, Thad Gourd, Bob Hammon, Colorado Onion Association