Reviewing the science to date on Corynespora cassiicola — incited leaf spot, Cotton Incorporated Senior Director Bob Nichols says the only clear answer at this point is that it’s a problem.



Nichols is working with researchers across the Southeast to undertake research on this emerging disease commonly known as target spot.

The disease was first found in southwest Georgia around 2005 and positively identified in 2009 by Bob Kemerait, University of Georgia pathologist.

 “Why does Nichols show up at a place?” Kemerait asks rhetorically. “Because there’s a problem. We have a problem.”



The question is how to manage it.

 Everything we think so far is being questioned, Nichols says, including foundational issues — such as, does the disease begin in periods of heavy rainfall or is heavy dew enough?

Answers to some questions haven’t been studied yet — such as whether nutrition plays a role in opening the door to this opportunistic disease, because target spot is apparently a disease of lush cotton and not of potash-deficient cotton.



Austin Hagan, Auburn University pathologist, saw more target spot in 2012 than in 2013, despite recording 30 more inches of rain this year at one of his research locations.

“The rainfall happened earlier this year suggesting there is an interaction with crop age, fertility demands, and the ability of target spot to establish itself” says PhytoGen cotton development specialist, Russell Nuti.



The priority questions for cotton growers are:

• Should susceptibility to target spot be considered when choosing varieties?

• Does target spot impact yield?

• Is a fungicide application economically advantageous?