Characteristics of turf insecticides

Some turf insecticides act very quickly while others take much longer to kill the target insect. In addition, some materials persist for several weeks and remain active, while others break down in a matter of a few days. Of the insecticides listed in these guidelines, a few work quite quickly (within one to three days) and break down within one to two weeks. These materials, often used for ‘curative’ applications, include: acephate (Orthene), and trichlorfon (Dylox). Some of the synthetic pyrethroids, like cyfluthrin (Tempo) and bifenthrin (Talstar) begin to act quickly but will persist longer if they penetrate the thatch and/or are applied to the soil.

Very few of the turf insecticides currently available for use in Massachusetts are intermediate in their “speed of efficacy” and persistence. These materials will often take three to seven days to begin to affect the target insects, but normally will remain active for three to five weeks, and sometimes even longer. Several “intermediate” materials have been taken off the market in the last few years, one that remains is carbaryl (Sevin).

Some insecticides, such as imidacloprid (Merit) or chlorantraniliprole (Acelepryn), are used for preventive insect control in areas that have a history of damage.  This use pattern is common for white grub management, but care must be taken to ensure that the material is in place and fully active when the grubs are in the most susceptible stage. These materials vary in how quickly they become active, but then normally remain active for several weeks or even months.
Please note that some listed materials have been somewhat inconsistent in their performance while others have provided similar levels of control through the years. Be sure to obtain current label information before using any insecticide.

Using insecticides preventively in an IPM program

Insecticides usually have either preventive or curative action against the pest for which they are used. Preventive materials are applied before a noticeable pest population develops. Curative materials are typically applied after populations reach a damaging level.

There are many components to an IPM program, including monitoring for pest activity, establishing tolerance levels, and considering cultural and biological management strategies whenever possible. One of the key tenets of IPM is to apply pesticides when a pest population exceeds a threshold level and only when all other avenues of control have been exhausted. In certain instances, however, preventive pesticide applications may be preferred to the alternative of waiting until a problem develops.  Part of the process in selecting and applying pesticides in an IPM program is to use application methods and materials that minimize the potential for environmental disruption.

For example, several turf insecticides [including the neonicotinoids and chlorantraniliprole (Acelepryn)] provide preventive protection against white grubs and are much less toxic than the older organophosphate materials that were used for many years. There are few cultural practices or effective biological control agents available that provide reliable control of white grub populations. Furthermore, in Massachusetts the use of the most effective curative material, trichlorfon (Dylox), is not allowed on school properties as specified in the Children and Families Protection Act (see the Pesticide Regulations section of this guide for more information). The only option for effective management of high populations of white grubs in this circumstance is preventive application with a neonicotinoid or chlorantraniliprole.

To be justified in an IPM plan, preventive insecticide applications must be based on scouting or other documentation of the potential for damaging populations from the previous season or seasons.

Insecticide resistance


There are several chemical classes of insecticides available to turf managers. Recently some turf insects (most notably, the annual bluegrass weevil) have developed resistance to certain chemical classes (in the case of the weevil, resistance to pyrethroids). This means that applications of certain products made now at rates that were effective several years ago do not kill as many insects. One of the most effective ways to delay the development of resistance is to avoid using insecticides in the same chemical class repeatedly. In most cases, you must also avoid using chemicals with the same mode of action. The Insecticide Resistance Action Committee (www.irac-online.org) has assigned “IRAC” numbers for each chemical class, and many chemical companies are putting these numbers on labels to make it easier for turf managers to incorporate this information into their decisions on chemical inventories. For example, any insecticide in the neonicotinoid class (e.g., Merit or Meridian or Arena) will have a black box with a white “4A” indicating the IRAC chemical subgroup. Carbamates (class 1A) and organophosphates (class 1B) are in the same group but listed separately because while the chemistry of the two classes of insecticides is different, the mode of action (cholinesterase inhibition) is the same.

The following information on insecticide characteristics will help turf managers avoid using the same chemical class repeatedly. Trade names referenced here are the first trade name under which the product was available in turf. Note that for some chemicals, there are many additional trade names not listed here.

Table 15. Characteristics of turf insecticides registered for use in Massachusetts.

ABW = annual bluegrass weevil; BTA = black turfgrass ataenius; ECF = European crane fly