Dan Anco Clemson Update News Peanut Notes No. 174 2020

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Worms

Worms are being reported in areas across the state, some below and some above threshold. Currently more in the upstate. Threshold is 8 worms per foot on good growing and lapped vines, 4 per foot on stressed vines or those that haven’t closed the row. Feeding amount threshold is 30% of canopy. Corn earworm in some places, fall armyworm in other places.

Corn earworm can often still be managed with an inexpensive pyrethroid, but make sure to follow up and check fields for worms to make sure we didn’t get a resistant batch. Pyrethroids can flare spider mites, so use should be considered carefully. Non-pyrethroid worm products are listed on page 61 of the production guide, and include Prevathon and Intrepid Edge – more expensive upfront, but less risky downstream. Tobacco budworm can look similar and is resistant to pyrethroids, to tell the difference the mandible needs to be pulled and looked at under magnification, or if moths are present that helps too. Here’s a link from North Carolina to a short video with some of the differences: (Distinguishing Tobacco Budworms From Corn Earworms)

Armyworms are in the same boat as the budworm with regards to pyrethroids not being effective.

Symptom lookalikes

Fungicides continue to go out for leaf spot and white mold protection. Sometimes, lesions that pop up on the leaves are not always due to disease, as many of you know. Surfactant/oil burn and sometimes herbicides can produce curious-looking spots on peanut leaves. Sometimes following prothioconazole application, which is an effective fungicide, spots can appear on some peanuts, and for some reason Georgia 09B seems to get it more often. I am not sure why. Attached are some images comparing spots that appeared after prothioconazole application with lesions caused by late leaf spot. Black/brown tufts on the underside of the lesion are key. Chlorothic areas around the lesion can be hit or miss and can vary based on time of observation.

Also attached are pictures showing false white mold versus white mold.

Anco 8-7-20 peanut images

Sicklepod has been popping up in several fields, particularly those with histories. Later into the season, 2,4-DB is the main go-to for management as it has a 45 PHI. It may need a follow-up application in 10 to 14 days.

Dan Anco

Extension Peanut Specialist and Assistant Professor

Department of Plant and Environmental Sciences

Clemson University – Edisto Research and Education Center

64 Research Road

Blackville, SC 29817

803-284-3343 x261 office

630-207-4926 cell

danco@clemson.edu

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