Phytotoxic Effects of Antifouling Compounds on Nontarget Plant Species

Plants of ten woody shrub species, euonymus, winter jasmine, spirea, golden privet, crape myrtle, forsythia, hydrangea, redbud, viburnum, and weigela, and two bedding plant species, marigold (annual) and dianthus (perennial), were sprayed over the top with sulfosulfuron, trifloxysulfuron-sodium, or halosulfuron-methyl at two times the label rate or sulfosulfuron was sprayed over the top with the label rate and then sprayed with the label rate 30 days later to determine phytotoxic effects of the herbicides. All of the sulfonyl urea herbicides tested were safe to use on euonymus, but none should be used on redbud, weigela, spirea, or crape myrtle. Trifloxysulfuron-sodium typically caused more phytotoxicity on all species tested except euonymus, while halosulfuron-methyl was least likely. Sulfosulfuron also should not be used on privet, hydrangea, or winter jasmine.

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SCREENING HERBICIDES FOR INJURY TO THREE CONTAINER-GROWN PANSY CULTIVARS

HortScience ◽

10.21273/hortsci.31.5.752a ◽

1996 ◽

Vol 31 (5) ◽

pp. 752a-752

Author(s):

J. Raymond Kessler ◽

Charles H. Gilliam ◽

Beth M. Wallace

Keyword(s):

Plant Species ◽

Woody Plant ◽

Pine Bark ◽

Liquid Formulation ◽

Woody Plant Species ◽

True Blue ◽

Phytotoxic Effects ◽

Bedding Plant

Little information is available on phytotoxic effects to annual bedding plant species from herbicides commonly used on container-grown woody plant species. Viol×wittrockiana `Crystal Bowl True Blue', `Imperial Antique Shades', and `Maxim Orange' were grown in 2.54-liter (#1) containers using an amended 6 pine bark: 1 sand medium. Five days after containerizing, each cultivar was either hand-weeded or treated with one of 13 granular or spray, pre- or post-emergence herbicides, within recommended rates in two separate studies. Herbicide phytotoxicity ratings were made 15, 30, 60, 90, and 120 d after treatment. Shoot dry weights were taken 120 d after treatment. Most injurious and persistently injurious herbicides were Rout 3G (oxyfluorfen + oryzalin), Pendulum 60 WDG (pendimethalin), and Ronstar 2G (oxadiazon). Low shoot dry weights closely correlated to injury rating. Least injurious herbicides included Pennant 7.8E (metolachlor), Surflan 4AS (oryzalin), Stakeout (dithiopyr), Pennant SG (metolachlor), and Derby SG (metolachlor + simazine). Southern Weedgrass Control, a granular formulation of pendimethalin, was among the least injurious, while Pendulum 60 WDG, a liquid formulation of pendimethalin, was most injurious. Evidence suggests that phytotoxic injury was greater on small, newly transplanted plants, though in some cases they were able to outgrow the injury.

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