Maleic hydrazide as a growth retardant

The usefulness of Maleic Hydrazide (MH) as a grass growth retardant when applied to urban, suburban and rural roadsides was evaluated from 1961 through 1964. The material was also tested on "hard-to-maintain" areas such as fence lines. MH was applied at various rates, in the spring and fall with and without an herbicide (weed killer). The areas on which the material was applied are normally mowed from 2 to 11 times a year, depending on the areas.

The application of MH at six pounds active material per acre in the spring generally retarded the height of grass. Lower rates and fall applications were generally ineffective. Depending on the area (rural or urban) and the effectiveness of the application, between zero and five mowings per year were saved.

When the turf was of other than excellent quality and the MH application was effective, annual weeds such as crabgrass, foxtail and ragweed tended to become very evident. When MH was used without an herbicide the roadside generally appeared more ragged than when not treated. When MH was applied with an herbicide and annual weed invasion, did not occur, a satisfactory appearing roadside was obtained. The period of time in the spring during which MH can be effectively applied is short, about two weeks. Rains, winds and springtime maintenance activities make proper timing of the application work very difficult under Minnesota conditions.