What Pesticide Do You Use on Morning Glory?

All Systems Go

• Systemic herbicides kill morning glory from roots to shoot tips. Spray plants with a ready-to-use systemic herbicide such as glyphosate in a 2 percent solution, covering all plant parts. Systemic herbicides are most effective when the plants are actively growing, so spray in the late spring, before morning glory sets seed. If regrowth occurs, wait until plants grow 1 to 2 feet long, and then spray again, so that plants are large enough to absorb an effective dose of herbicide. Glyphosate kills most plants -- spray only on still days, cover desired plants with cardboard, and unwind morning glory and lay it on newspaper before spraying. Wear long pants, a long-sleeved shirt and gloves when handling any pesticides.

Get Them Young

• To prevent morning glory seeds germinating, apply a pre-emergent herbicide. Trifluralin, oryzalin, or pendimethalin control morning glory seedlings and regrowth from roots, preventing the plant from reappearing in cleared areas. Seeds can persist in the soil for decades. Spread a granular herbicide containing 1.71 percent pendimethalin at a rate of 3 ounces per 100 square feet in spring. Irrigate after spreading to activate the chemical. Pre-emergent herbicides work best in established garden beds. Effective only in the top 1/2 or 1 inch of soil, digging or tilling the ground after application reduces their performance.

Turf Wars

• Mowing weakens morning glory plants growing in lawns, but established plants continue to grow below the reach of mower blades. Infestation might only be noticeable when flowers appear above the grass. Products containing dicamba or 2,4-D control morning glory without harming grass. Spray lawns with a ready-to-use pesticide containing 12 percent 2,4-D and 0.5 percent dicamba in spring, on a dry day when the temperature is between 45 and 90 degrees Fahrenheit. Spray again after two or three weeks and once more after a similar interval.

Control Culture

• Herbicides combined with cultural practices offer the best long-term control for morning glory. Hoeing every two or three weeks weakens mature plants that re-sprout after herbicide treatment and kills seedlings before they establish. Hoeing can keep morning glory in check until the following spring, when pesticide applications begin again. By itself, hoeing takes three to five years to kill adult plants. Covering morning glory with landscape fabric or black plastic sheeting also kills plants in three to five years. Bury the edges of sheeting under soil to hold it in place, and spread shredded bark or another mulch over the top. After removing the sheeting, apply a pre-emergent pesticide to prevent morning glory seeds from germinating.