Re-cropping after Callisto or Command?

Kristen Obeid, OMAFRA Weed Specialist – Horticulture

Callisto and Command are relatively new herbicides to various horticulture crops in Ontario.  They both cause bleaching symptoms even though Callisto is a Group 27 herbicide and Command is a Group 13.  Group 27 and Group 13 herbicides are categorized as carotenoid biosynthesis inhibitors.  Group 27 herbicides are also frequently referred to as HPPD inhibitors.  This refers to the inhibition of p-hydroxyphenyl pyruvate dioxygenase (HPPD).  The  inhibition of HPPD gives rise to bleaching symptoms on new growth.

Command
Command injury on tomato due to drift.

clomazone cauliflower 2
Command injury on cauliflower from heavy spring rains.

Both Callisto and Command are broken down by soil microbial activity.  Drought, cold temperatures and low pH soils reduce microbial activity.  These herbicides are bound to organic matter which also reduces the rate of degradation.

It is very important to know what herbicides have been used on any land prior to planting a new crop, to determine if there will be concerns with herbicide residues.  This is particularly important when renting or trading land.

Below is a table with the re-cropping intervals required in certain crops, for other crops consult the herbicide label.

Re-cropping intervals (in months) after Callisto or Command

CropCallistoCommand
Asparagusf
Beans, Lima2216
Beans, Snap2210
Beets, Redf16
Beets, Sugarf16
Broccolif10
Brussels sproutsf16
Cabbagef16
Carrotsf16
Cauliflowerf16
Celeryf16
Corn, Sweet10
Cucumberf
Garlicf16
Herbsf16
Lettucef16
Muskmelonf16
Onionsf16
Parsnipsf16
Peas2210
Peppersf
Potatoes1110
Pumpkinf
Rutabagaf16
Spinachf16
Squashf10
Tomatoes (transplanted)1116
Watermelonf16
✓registered for application on this crop
f – field bioassay required, user assumes liability for all crops not indicated on the label

Field bioassay Service: A&L Laboratories www.alcanada.com

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