Rating Disease in the Field May Help in Indicating Mycotoxin (DON) Potential

A quick indicator of potential DON mycotoxin production in the field is being investigating by Dr. Art Schaafsma which begins by rating the disease level in the field. This is done by examining corn ears in the field and determining a average rating based on a 1 to 7 scale (Figure 1). The image on the right illustrates this rating system (Figure 2). Dark areas on the scale include obviously damaged kernels plus healthy kernels surrounded by (mycelium). Examine the ears very carefully not only for damaged kernels, etc but also for fungal growth (mycelium) between the kernels.

Figure 1 - Ear Molds Rating System Used to Evaluate Corn Hybrids
and Disease Levels In the Field. Rating System is based
on a 1 to 7 rating with 1 being the lowest (0%)
and 7 being the highest (76-100%) infection.(text equivalent of graphic)

Figure 2 - Visual Ear Rot Ratings from a low (left) to higher (right). (text equivalent of graphic)

Once the average field rating has been determined, the potential DON mycotoxin levels in the field can be approximated by using the regression graph in Fig. 3. For example a rating of 2 (<3% infection) would suggest DON levels below 1ppm. As mentioned this system still needs to be field validated so be cautious.

Fig. 3 -The accuracy of the Corn DON Calculator at this time is
better for those fields which have a rating of 3or under. (text equivalent of graphic)

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