Broccoli trial results: which varieties of broccoli stand up to disease and heat stress?

Disease pressure and climate change pose significant challenges to growing broccoli in the Midwest. For the past two summers, we've been conducting collaborative trials with growers across the region to identify broccoli varieties that can withstand increasing disease pressure and heat stress.

Since around 2018, the pathogens black rot (Xanthamonas campestris pv. campestris) and Alternaria (Alternaria spp.) have become common on farms and in gardens, with some growers reporting 80-100% yield losses. Especially for organic growers, varietal tolerance can be a powerful tool for disease management. 

We conducted replicated broccoli trials at the Southern Research and Outreach Center (SROC) in Waseca, Minnesota, where we inoculated plots with black rot (Xanthamonas campestris pv. campestris). We also partnered with 88 farmers and gardeners to conduct mini trials at their farms and gardens. Our goal was to screen for varieties of broccoli with tolerance to the pathogens black rot and Alternaria, as well as environmental challenges like warm fall nights and high heat in the summer. 

Our new report outlines the results of the 2022 trial with overall takeaways and variety recommendations from both 2021 and 2022. Check it out here! 

Natalie Hoidal and Charlie Rohwer at the SROC. Image: Allison Sandve