By Darren Hefty
Ag PhD has teamed up with the American Phytopathological Society (APS) to launch the Ag PhD Corn Disease Field Guide. It’s a free download and has great pictures and information about many of the most problematic diseases impacting corn. APS has great information, so if you are a corn farmer you will absolutely love this app. One of the diseases you’ll find in the Corn Disease Field Guide is one that was widespread again this year but hasn’t been getting enough attention in the industry: anthracnose stalk rot (ASR).
SYMPTOMS
Disintegration of pith tissue, a symptom of anthracnose stalk rot.
Source: APS Press.
Black lesions on the stalk, symptomatic of anthracnose stalk rot.
Source: APS Press.
If you split open corn stalks at the end of the season and saw the pith of the stalk in bundles with brown areas beginning around the nodes, you likely had ASR. If you noticed top die-back in your corn fields this year, you may very well have had ASR. If you saw both of those things and also had shiny, dark lesions on the stalk rind as well, ASR is almost certainly the culprit.
FAVORABLE CONDITIONS
Reduced tillage and continuous corn are two factors that often allow anthracnose stalk rot to build in a field, as infected corn residue is the main way this disease pathogen overwinters. The disease spores can be easily spread with wind and rain at multiple times during the season. High temperatures and periods of stress after pollination lead to more problems with ASR.
MANAGEMENT
There are no crop protection treatments like fungicides that are effective for stopping anthracnose. Tillage and crop rotation away from corn can certainly help. However, the best chance you have at reducing ASR in your corn this year is to look for corn hybrids with increased levels of tolerance or even resistance to the disease. With hybrid resistance, ask your seed dealer if the resistance is for ASR or anthracnose leaf blight as these are two different diseases. In addition, we find that managing all the other agronomic factors in your field leads to healthier plants and fewer diseases. For example, have ample and balanced fertility in your soil. We are finding terrible deficiencies across the country with nutrients including potassium, manganese, copper, and boron, so make sure you are soil testing for ALL the fertility you need, not just N, P, and K. Also, having good drainage, as well as great weed and insect control are other important steps toward having a crop better set up to defend itself against ASR.
Download the Ag PhD Corn Diseases Field Guide for your iOS and Android Mobile Devices!
Android – https://play.google.com/store/apps/details?id=com.agphd.corndiseases&hl=en
iOS – https://itunes.apple.com/us/app/corn-field-guide/id1128686990?mt=8