Organic Management of
Brassica Diseases

Efficacy Study of Biorational Pest Control Materials

Brassica crops are susceptible to a number of plant pathogens which are often triggered by warm, wet weather.

In the Northeast, black rot, downy mildew, and Alternaria are common fungal diseases of brassicas, but to date there are few effective organic management solutions. These diseases can spread by contaminated seed, equipment, and weed seeds. As a result, broccoli heads can rot and become unsalable.


This trial tests the impact of Brassica bio-rationals—low-risk pesticides that contain naturally occurring beneficial microorganisms—on broccoli.

In collaboration with Cornell Cooperative Extension Eastern NY Commercial Horticulture (CCEENYCH), the trial evaluated seven bio-rationals and two copper formulations in a replicated trial of broccoli. Researchers evaluated the biorational fungicides on broccoli grown at the Farm Hub where Black Rot (BR), Downy Mildew (DM) and Alternaria Leaf Spot/Head Rot (ALS), have all posed persistent production challenges.

The goal is to provide growers with better management recommendations in our regional climate.

Trial Design:

The 2020 trial was designed to generate data to help answer the following research questions:
  1. What impact, if any, do pre-transplant applications of Badge X2 (Copper Oxychloride, Copper Hydroxide) or LifeGard (Bacillus mycoides isolate J) have on foliar disease severity observed over the production season when compared to broccoli plants in an untreated control that received no pre-transplant fungicide/bactericide?
  2. Is there any synergistic disease suppression effect of combining pre-transplant biorational product applications with in-field biorational applications?
  3. How well can each of the nine biorational products work alone to suppress BR, DM, and ALS in broccoli when compared to an untreated control that received no in-season fungicide/bactericide applications?
  4. Can statistically significant differences in marketable broccoli yield be observed in a small-plot randomized complete block design trial intended to primarily evaluate disease severity?
  5. What trends in disease severity reduction can be observed from a single year product screening trial in order to inform the development of season-long biorational programs?

The researchers used a randomized complete block design with four replicates and ten treatments for this trial.

Each treatment plot was 15 bed-feet long and consisted of three rows of broccoli. The three pre-transplant biorational treatments were randomized and applied at the row level within each 15 bed-foot long plot. The ten field applied biorational treatments were randomized and applied at the plot level over each of the three rows in each 15 bed-foot
long plot.

The statistical analyses for the data were completed using a generalized linear model to evaluate the row-level pre-transplant treatments, the plot-level field treatments, and the
interaction between the pre-transplant and in-field treatments for statistically significant difference at p<0.05. Multiple comparisons of treatment means were made by applying a post-hoc Tukey’s HSD at p<0.05.