As we turn the page on 2020 and move ahead to 2021, it’s never too early to think about insects. Although we can’t predict specific issues we will face during the growing season in March, we can think about what we may encounter and ways to mitigate loss from various pests. As we discuss some issues, keep in mind that scouting and spraying only when necessary is the best way to maximize the return on investment and mitigate the risk of flaring secondary pests.
Snails and Slugs
Snails and slugs are a growing issue for many producers in the southeast. Although snails are not known to feed on plants like slugs, they can cause issues with contamination at harvest. Slugs and snails tend to heavily infest fields during years that are wet and in fields with high plant residue (reduced/no-till). Unfortunately, few control options exist outside of tillage. Insecticides have no effect and although some baits are commercially available, they are pretty expensive and not very effective.
Thrips are a pest that we expect to infest peanut fields every year. Although damage from thrips feeding may cause issues, typically transmission of tomato spotted wilt virus (TSWV) is of the greatest concern. The best way to manage TSWV is to plant high yielding resistant varieties. Some cultural practices may be employed to help manage thrips and TSWV such as planting date, reduced or strip-tillage and planting twin-rows. Early planted peanuts may be at a higher risk of infestation and infection. At-plant insecticides should also be used to manage thrips. Phorate (Thimet) is the only product that has shown the ability to reduce the incidence of TSWV but imidacloprid (Admire Pro, others) is another option to manage thrips. Supplemental foliar thrips sprays may be needed if plants are stunted from other factors (herbicide injury, seed quality, nematodes, etc.).
Several species of defoliating caterpillars including tobacco budworms (TBW), cloverworms (GCW), corn earworms (CEW), soybean loopers (SBL) and velvetbean caterpillars (VBC) may infest peanuts at various times during the season. Sampling is important when defoliation is observed, because although our thresholds (=4/row foot) aren’t different for the various species (or complex of species), identification is important. VBC and GCW are relatively easily controlled with most labeled insecticides, however if the SBL (which has only 2 prolegs) is the primary species, the newer chemistries (Prevathon, Intrepid Edge, Besiege, etc.) may be required.
Spider Mites are a likely pest in most fields at low levels all season. Their numbers explode in hot, dry conditions and can sometimes be worse following sequential applications of broad-spectrum insecticides. Currently, Comite II and Portal are the only options available for spider mite management.
Lesser Cornstalk Borers
Lesser Cornstalk Borers (LCB) can be a major pest in hot, dry periods, particularly when stands are skippy earlier in the season. Late planted, non-irrigated sandy fields are at increased risk of LCB. Sometimes a well-timed rain or irrigation event is all that is needed to manage LCB, but when rain is lacking in dryland fields insecticides may be needed. Prevathon, Diamond and Besiege are options to control populations and reduce damage.
Burrower bugs are a pest without many solutions currently available. Burrower bugs tend to be worse in hot, dry years and in reduced till fields. Deep tillage can help reduce populations but obviously can only be done prior to planting. If infestations are found in-season, granular chlorpyrifos is the only option. Fields that have had issues with burrower bugs in the past should be monitored in dry years for problems moving forward.
The best way to manage insects is to scout fields and treat only when necessary. Insects are different from other pests and most times should not be managed preventatively or on a schedule. Often, decisions are made on a field-by-field basis. We have a lot of resources about peanut IPM on the ACES website, the Alabama IPM Communicator, Alabama Peanut IPM Facebook page, Twitter, the Alabama Crops Report Newsletter and the Alabama Crops Report Podcast—which will be released soon.
For more information from ACES Specialists regarding peanut management recommendations visit the 2021 Peanut Production Guide or watch the 2021 Peanut Production Seminars sponsored by the Alabama Peanut Producers Association.
Trade names are used only to give specific information. The Alabama Cooperative Extension System does not endorse or guarantee any product and does not recommend one product instead of another that might be similar.