Cotton Aphid Fungus Showing Up in Fields

Aphids have been showing up in fields in the last couple of weeks in numbers varying from none to heavy in certain areas of fields.  Here is a photo of a “hot spot” in a field in Dillon County.

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Along with these populations of aphids, the pathogenic aphid fungus Neozygites, has started showing up.  So long as the humidity stays up, this fungus will move quickly throughout a field and take out aphid populations within a week to 10 days.  Here is a photo from Clemson Entomologist Jeremy Greene showing multiple aphids covered in the fuzzy, grey looking fungus.

Aphids with fungus - Greene 2015

Here are a couple microscope pictures showing the fungal spores emerging from the dead aphids.

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When this shows up in a field, we don’t need to apply insecticides for aphids.  Look closely for this fungus when scouting fields so unnecessary sprays can be avoided.  Along with aphids, insecticide applications can wipe out beneficial insects that keep other pests like spidermites and caterpillars in check.  Some of the beneficials out there right now include lady bugs, lacewings, syrphid flies, parasitic wasps, ground beetles, spiders, and assassin bugs like the one pictured below.

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For more info on aphids in cotton, check out page 103 of the SC Pest Management Guide.

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