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Recropping after Callisto or Command?

Callisto and Command are relatively new herbicides in Ontario. Although they have different modes of action (Callisto is a Group 28, while Command is a Group 13 herbicide), they both produce bleaching symptoms on plant leaves.

Figure 1. Callisto injury symptoms on peas

Figure 2. Command injury symptoms on beans

Both Callisto and Command are broken down primarily by soil microbial activity. This may leave small residues in varying amounts, depending on conditions in the soil. The big question is: What can be safely grown the year after applying these new herbicides?

Here are the Recropping intervals for horticultural crops after Callisto:

• After 22 months: Lima beans, snap beans, peas
  
• After 11 months: Potatoes, transplant tomatoes

Here are the Recropping intervals for horticultural crops after Command:

• After 16 months: Asparagus, Lima beans, red beets, sugar beets, Brussels sprouts, cabbage, carrots, cauliflower, celery, garlic, herbs, lettuce, muskmelons, onions, parsnips, rutabaga, spinach, transplant tomatoes, watermelons
  
• After 10 months: Snap beans, broccoli, sweet corn, cucumber, peas, peppers, potatoes, pumpkins, squash

If your crop is not listed, a Field Bioassay is required. This involved planting a test strip of the desired crop in the field to assess the safety for planting the following year. A Field Bioassay Service is also available to assist in making a re-crop decision. Contact the Alberta Research Council, IPM Unit at 1-780-632-8218.

Interested in field crops? Information on Recropping for Field Crops can be found in Table 4-3, Publication 75, Guide to Weed Control.

Learn more:

• OMAFRA Publication 75, Guide to Weed Control
• Table 4-3: Herbicide Crop Rotation and Soil pH Restrictions (Field Crops)