Dr. Darren Robinson, Ridgetown Campus – University of Guelph; Janice LeBoeuf, OMAFRA, Ridgetown
Sencor moves upward in the plant in the transpiration stream, so injury symptoms are typically seen in older leaf tissues. The leaves will show chlorosis (yellowing or whitening) between the leaf veins, and burning around the leaf margins.
Pinnacle translocates in the phloem to new developing tissues, so injury symptoms will be seen in the ‘heart’ of the plants at the growing points. Injured plants will cease growth and turn chlorotic within days of application, especially if the herbicide is applied in hot weather to sensitive varieties. Check for variety sensitivity with processing representatives. For fresh market varieties, always test on a few representative plants before spraying the whole block.
Prism injury symptoms may be observed in hot, humid weather, and will appear in the youngest leaves. Symptoms include chlorosis and slight stunting. Variety sensitivity to Prism is not as prevalent as to Pinnacle.