Effects of chemicals on root intrusion into subsurface drip emitters

Root intrusion into emitters poses a threat to the long-term success of subsurface drip irrigation systems, particularly in fibrous-rooted crops. Bermudagrass was grown in a greenhouse to examine the effectiveness of chemicals in preventing root intrusion into subsurface drip emitters in two-year, two-part experiments. During the first year of study, two acids, sulfuric and phosphoric, and two pre-emergence herbicides, trifluralin and thiazopyr, were tested on bermudagrass grown in small pots. As an initial step for the emitter clogging experiment, the first-year experiment focused on the effectiveness of the chemicals in preventing overall root growth in pots saturated with either trifluralin or thiazopyr. Only thiazopyr significantly inhibited root growth, and visual quality of shoot growth in the thiazopyr-treated pots was lower than the observed quality in the rest of the treatments and in non-treated bermudagrass. During the second year, nine treatments were prepared based on the first-year study, and were examined for control of root intrusion into actual subsurface drip emitters. Emitters were completely free of roots with thiazopyr treatment at the highest concentration, and with the trifluralin-impregnated emitter treatment under water stress. Root and rhizome growth was generally unaffected by treatment. As expected, shoot visual quality was lowest in the thiazopyr treatments. Nevertheless, it met the minimum quality standard.