The Effect of Herbicides on Lateral Roots and Nut Quality of Pecans

Trifluralin a,a,a -trifluoro-2,6-dinitro- N,N -dipropyl- p -toluidine) applied at 1.12 kg/ha inhibited lateral root development on field-grown pecan (Carya illinoensis (Wang.) K. Koch) seedlings. In a greenhouse study, inhibition of lateral roots, club-shaped radicles, and restricted penetration of tap roots resulted when pecans were planted in soil treated with 1.0 ppm trifluralin. When pecans were planted above soil treated with trifluralin, normal root development occurred only in the soil which had not been treated. Lateral roots were inhibited in the trifluralin-treated soil. Pecan nuts from trifluralin plots were smaller than those collected from controls, but other factors of quality were statistically equal or superior to nuts harvested in plots which had been treated with 2-chloro-4,6-bis-(ethylamino)- s -triazine (simazine) and 3-(3,4-dichlorophenyl)-1,1-dimethylurea (diuron). The smaller nut size was attributed to lateral root inhibition by trifluralin early during nut development.