Thrips Control With Late Plantings Peanut Notes No. 47 2018

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The following is an abstract and summary from a paper Rick and I are trying to get published in Peanut Science. Some peanuts will be planted in early June and there may be a tendency to cut costs and leave of sprays for thrips. Our work showed that late-planted peanut needs to be protected from thrips injury just like earlier-planted peanut in order to protect yield.

Abstract
Planting date may affect pest incidence and severity in peanut. Research was conducted from 2013-2016 in North Carolina to determine tobacco thrips [Frankliniella fusca (Hinds)] injury and pod yield when peanut was planted in early May, mid-May, and late-May when phorate was applied in the seed furrow at planting, acephate was applied to emerged peanut 3 weeks after planting, or when both insecticides were applied. Differences in visible injury to peanut caused by tobacco thrips feeding were observed across years, planting dates, and insecticide treatments. Applying either phorate or acephate was often as effective as the combination of both insecticides in preventing injury caused by tobacco thrips although in some instances applying both insecticides was more effective than a single insecticide. Visible injury caused by tobacco thrips was often greater when peanut was planted in early May compared with later plantings. Peanut yield was protected equally from tobacco thrips injury by phorate, acephate, and the combination of both insecticides. Planting date and insecticides affected peanut yield independently suggesting that strategies for managing tobacco thrips will not differ across planting dates in North Carolina. Peanut yield was greater in 2 of 4 years when planted in mid-May compared with planting in early or late-May.

Summary
Tobacco thrips are a major insect pest for peanut producers in North Carolina and injury caused by this insect can reduce peanut yield (Brandenburg, 2017). Planting peanut in mid- and late-May reduced injury from thrips compared with injury when peanut was planted in early May. Phorate in-furrow, acephate applied after POST after peanut emergence, and phorate followed by acephate reduced thrips injury and protected yield equally compared with non-treated peanut. While insecticides did increase yield, these data suggest that peanut response to planting date is independent of insecticide treatment. Even though considerable differences in peanut yield were noted for the interaction of year and planting date (Table 3), lack of an interaction of planting date with either insecticide main effect or interaction of phorate and acephate strengthens the argument that recommendations on insecticide use for protection from thrips injury should not be adjusted based on planting date in North Carolina. The present work also supports the current recommendation of planting peanut in North Carolina in mid-May.