How can I control grubs in the spring?
30 Jan, 2009 By: Bal Rao LDB SolutionsQ. For white grub control in home lawns we have used Merit insecticide. We are also interested in using Mach 2 insecticide. We are currently in the process of reviewing our product inventory and future purchase options. We would appreciate your comments regarding the use of Merit and Mach 2 insecticides next spring against over-wintered grubs and later against new generations of grubs in summer and fall. What other products can we use for grub control? (MI)
A. Success in white grub management depends on identifying the grub species and applying treatments at the proper time. When the larvae are younger and smaller it is easier to manage than when they reach mature third instar.
The insecticides Merit (imidacloprid) and Mach-2 (halofenozide) are being used by a number of lawn care operators for managing white grubs. Imidacloprid trade names include Merit, Bayer Advanced™ Season-Long Grub Control and Scotts GrubEx, Xytec and several other trade names. Become familiar with a particular trade name product, their performance, etc., before purchase.
Mach 2 is an insect growth regulator that affects larval molting process and prevents development. This product works well on young, early stages of grubs. As the larvae mature, the performance of Mach 2 may vary. If you are considering using a halofenozide insecticide, use it when the larvae are young. Therefore, using Mach 2 in the spring against overwintering mature 3rd instar grubs or later when the new grubs reach 3rd instar in the fall would be ineffective. Halofenozide can be purchased under trade names such as Mach 2, Spectracide, Grub Stop, and Hi-yield Kill-a-Grub.
Both imidacloprid (Merit) and halofenozide (Mach 2) can be applied about six weeks before egg laying takes place. Or, start treating when peak adult beetles are found flying around. This should help in managing young larvae when they peak in early fall. Generally, around mid-June/July should be good as a preventive treatment.
In addition to the above products, other insecticides such as thiamethoxam (Meridian), clothianidin (Arena), or combination products such as Allectus (Merit plus Talstar = bifenthrin) and Aloft (Arena plus Talstar) may be considered. These products can be applied early in the season to manage the young newly hatched grubs in the fall.
For managing mature third instar grubs in spring or late fall, consider using rescue treatments of trichlorfon (Dylox) or carbaryl (Sevin). The pyrethroid insecticide would be less effective against white grubs because these products bind to soil particles and may not reach the target pest. Grubs generally feed at the soil and root interface area. Therefore, if there is too much thatch the effectiveness of all the above products would be poor. Consider providing a thatch management program.
Efficacy can be improved by post watering. This would help move the product through the turfgrass layers to the target zone where grubs are feeding on roots. Failure to post water or rain may result in variable results.
Read and follow label specifications for best results.
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