Pest e-alerts, 07/25/2012, v.11 no.34

              Entomology and Plant Pathology, Oklahoma State University
127 Noble Research Center, Stillwater, OK74078
405.744.5527
Vol. 11, No. 34
http://entoplp.okstate.edu/Pddl/
Jul 25, 2012
Peanut Disease Update
John Damicone, Extension Plant Pathologist
I visited the peanut plots last week at the Caddo Research Station and noticed that early leaf spot (Fig. 1) was present at low levels in a field trial planted to Spanish peanuts. While it is hard to become concerned about foliar disease in this hot weather, once the weather breaks and it rains again (I am being optimistic here), look for leaf spot to rapidly increase. Examining the peanut leaf spot advisory program (http://agweather.mesonet.org/) shows that since June 1, sufficient infection hours have accumulated in most production areas to establish leaf spot (Table 1). It takes 36 infection hours before spots appear. This is an approximation assuming that spores of the fungus are present and plentiful. Crop rotation typically delays disease development.
Fig 1. Early leaf spot of peanut.