Treatment Thresholds for Sugarcane Aphid in Sorghum

Because this insect is so new, we are in no-man’s-land as far as thresholds.  Here are three thresholds based on experience and data from the Midsouth and Texas:

Growth Stage Aphid Number Injury
0-3 leaves 10 Visible damage, yellowing or reddening of leaves
4-7 leaves 50 Visible damage, yellowing or reddening of leaves
8+ leaves 100  One dead leaf
Pre-boot 200  One to two dead leaves
Boot 500  Two dead leaves
Heading+ 750  Two to three dead leaves
Growth Stage Threshold
Pre-boot 20% infested plants with localized area of honeydew and established aphid colonies
Boot 20% infested plants with localized area of honeydew and established aphid colonies
Flowering-milk 30% infested plants with localized area of honeydew and established aphid colonies
Soft dough 30% infested plants with localized area of honeydew and established aphid colonies
Dough 30% infested plants with localized area of honeydew and established aphid colonies
Black layer Heavy honeydew and established aphid colonies in head (treat to avoid problems at harvest)

Finally, another threshold, promoted by the United Sorghum Checkoff Program can be found here.  It is based on aphid numbers that can be estimated from photos.  The United Sorghum Checkoff Program provides excellent resources and helpful videos concerning this pest on their website (click here).

Written By

Dr. Dominic ReisigAssociate Professor and Extension Specialist (252) 793-4428 Entomology and Plant Pathology - NC State University

Posted on Jul 28, 2015

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