Category Archives: Diagnostics

Downy mildew of brassica vegetables

Downy mildew of brassicas (Hyaloperonospora parasitica syn. Peronospora parasitica) is a fungal-like oomycete that can be devastating in cooler, wet weather. While the ideal temperature for downy mildew development is 8-16˚C it can infect in temperatures outside that range. Prolonged leaf wetness due to fog, dew, or evening irrigation can create ideal conditions for the pathogen to develop.

Downy mildew is most devastating on Continue reading Downy mildew of brassica vegetables

Stemphylium is the new Botrytis

Stemphylium leaf blight (Stemphylium vesicarium) of onion starts as yellow-tan, water-soaked lesions developing into elongated spots. As these spots cover the entire leaves, onions prematurely defoliate thereby reducing the yield and causing the crop to be more susceptible to other pathogens. Stemphylium was first identified in Ontario in 2008 and has since spread throughout the Holland Marsh and other onion growing areas in southwestern Ontario.

Stemphylium leaf blight can sometimes be misdiagnosed as Continue reading Stemphylium is the new Botrytis

Herbicide injury symptoms in tomatoes

Darren Robinson, University of Guelph, Ridgetown Campus; Janice LeBoeuf, OMAFRA, Ridgetown

Introduction

Herbicides are useful tools for the management of weeds.  The herbicides registered for use in tomatoes are selective in their activity, injuring or killing weeds while being safe to use on the crop. Crop injury may occur, generally when a crop is stressed beyond its ability to adequately deal with a herbicide application.  Injury due to herbicides can arise as a result of several factors, including weather-related stress, soil factors such as light soil texture and low soil organic matter, shallow planting and sensitive crop varieties.  The pages in this section contain information on herbicide injury for several products registered on tomatoes in Canada. Continue reading Herbicide injury symptoms in tomatoes

IPM Scout Training Workshops Begin This Week

ONfruit

The free OMAFRA IPM scout training workshops are available for those who will be scouting horticultural crops this year. Be sure to register if you or your scout are planning to attend!

To register, please contact OMAFRA’s Agricultural Information Contact Centre at 1-877-424-1300 or ag.info.omafra@ontario.ca.

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Resources on weed management

Kristen Obeid, OMAFRA Weed Specialist – Horticulture

Internet

weedinfo.caWeedinfo.ca: If you are trying to identify a weed, find the newest information on herbicide resistance and other emerging issues in weed management you need to visit weedinfo.ca.

Provincial Weed Page: http://www.omafra.gov.on.ca/english/crops/insects/weeds.html

Ontario Crop IPM: Know how and why it is important to scout and identify weeds, as well as diagnose herbicide injury. Continue reading Resources on weed management