A purple twilight sky over a field of cabbage.

Brassicas

Broccoli, Brussels sprouts, cabbage, cauliflower, collards, kale, kohlrabi, radishes, rutabaga, and turnips

Brassicas

Cabbage Maggot Control

Insecticide Options for Cabbage Maggot Control

Since Lorsban along with its generic products (active ingredient chlorpyrifos) was banned in 2021, the Cornell Vegetable Program has been working with Brian Nault, Cornell Entomology, to conduct on-farm cabbage maggot trials annually from 2021 to 2023 and in 2025 in search of an effective alternative. Our key research findings are provided in the Summary of Relative Performance of Insecticide Options for Cabbage Maggot Control in Brassicas in New York, 2026.

Close-up of two radishes that have brown corky scarring and a hole in them.

Swede Midge Control

Crop Rotation Recommendations for Swede Midge

Cornell research has demonstrated that brassica crop rotations of 500 ft (down from 3,000 ft) and 3 months (down from 3 years) could effectively "crash" a swede midge population when fields are secluded from each other, making crop rotation a much more feasible strategy for small farms. The NEW Crop Rotation Recommendations for Swede Midge fact sheet details the new crop rotation recommendations and provides information on the pest's life cycle, biology, and crop preferences in addition to real-world examples of crop rotation. The crop rotation strategies were developed to serve the needs of small organic farmers, but have utility for conventional farmers as well. 

Manage Swede Midge in Organic Brassica Production

There are two methods to use insect exclusion netting to manage swede midge in brassicas:

  1. As a cover over top of susceptible brassicas to exclude/protect the crop from swede midge; and
  2. To include inside the netting swede midge that emerge from soil so that they cannot escape and attack susceptible brassicas outside the netting. In this case, a non-susceptible crop is grown under the netting.
Using Insect Exclusion Netting to Manage Swede Midge in Organic Brassicas
A section of 4-ft x 4-ft low tunnel covered with white netting. A row of small rocks is holding the netting to the ground.

Alternaria Leaf Spot and Head Rot

The Fungicide "Cheat Sheet" for Alternaria Leaf Spot and Head Rot in Broccoli and Other Cole Crops, 2024 provides a list of fungicides (both conventional and organic) that are labeled in broccoli and other common Cole crops, for which Cornell research has shown to be effective for control of Alternaria leaf spot (ALS) and head rot. Many tips on how to build a successful fungicide program for ALS and downy mildew that adheres to best fungicide resistance management are included.

NOTE: Due to known development of ALS developing fungicide resistance to FRAC 7c, Cornell is not longer recommending FRAC 7 fungicides for managing ALS and head rot in brassicas.

Due to lack of funding, we were unable to continue our research on Alternaria leaf spot and head rot in broccoli in 2024 or 2025. Thus, our recommendations for control of this disease remain the same.