Loss of Spray and Pelleted Picloram in Surface Runoff Water1
- R. W. Bovey2,
- C. Richardson2,
- E. Burnett2,
- M. G. Merkle3 and
- R. E. Meyer2
This investigation was conducted to determine the concentration of piclorum (4-amino-3,5,6-trichloropicollnic acid), applied as the pelleted formulation, in surface runoff water that may move from a treated watershed to untreated areas as a result of natural or simulated rainfall. Movement of surface and subsurface applied picloram in surface runoff water was also investigated.
The potassium salt of pelleted picloram was applied at 2.24 kg/ha (acid equivalent) to a 1.3-ha rangeland watershed supporting stands honey mesquite (Prosopis juliflora [Swartz] DC. var. glandulosa [Torr.] Cockerell). Surface runoff of 1.5 cm from a 2.1-cm rain received 2 days after treatment contained an average of 2.8 ppm picloram. Picloram content declined rapidly and runoff water contained < 5 ppm picloram by 2.5 mo after application. Loss of the potassium salt of picloram from grassland watersheds in surface runoff water was similar whether the picloram was applied as an aqueous spray or pellet. Picloram applied subsurface was lost in surface runoff water, but in lower concentration than when applied to the soil surface.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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