Published online by Cambridge University Press: 12 June 2017
Preemergence (PRE) and postemergence (POST) herbicides were sequentially applied to tall fescue over a 2-yr period to determine the lowest herbicide rates needed for acceptable large crabgrass control. Prodiamine was the only PRE herbicide that provided full-season large crabgrass control in tall fescue turf. The control was 85% in plots treated at one-third recommended rate (0.3 kg/ha) and 96% at the full rate (0.8 kg/ha). Sequential applications of oxadiazon at one-third recommended rate (1.1 kg/ha) in late February followed by fenoxaprop (0.2 kg/ha) in June controlled 85% large crabgrass in late August. Control was similar in mid-August when pendimethalin, dithiopyr, or oryzalin at one-third recommended rates was followed by fenoxaprop, but was not acceptable (≤ 74%) by late August. In most instances, large crabgrass control was higher when fenoxaprop followed the PRE herbicide application than with MSMA. Reduced herbicide rates may not provide full-season large crabgrass control in other areas with different soil and weather conditions. Tall fescue quality was not affected by prodiamine, dithiopyr, and oxadiazon. In 1996, pendimethalin at 3.3 kg/ha reduced turf quality 16% and oryzalin at 2.2 kg/ha reduced quality by 46%. In 1995, MSMA reduced the quality of tall fescue more (≤ 21%) than fenoxaprop (≤ 10%). When compared to the use of PRE and POST herbicides alone, sequential PRE plus POST herbicide programs did not affect turfgrass quality.