Goss's Wilt

Nov 01, 2020

               Goss’s wilt and Goss’s leaf blight are diseases that you’ve probably heard of, but not worried about too much.  It is usually thought of as a disease that affects the big corn producing states.  However, recently it has been spreading and becoming more prevalent in North Dakota.  Although, it seems like a recently developed disease it was first identified in Nebraska back in 1969.  The first documented case in North Dakota came in 2011.  A survey done by NDSU Extension in 2016 discovered the disease in 24% of the surveyed fields.  Most of those had low pressure, but there was one field with over 90% infection rate.  For the last four years I could find it somewhere in just about every corn field I walked into. 
               Goss’s is a bacterial disease that shows up in two different phases.  One phase is a systemic infection that can cause wilting and leaf blighting.  Corn plants are most susceptible to systemic infections when they are in the seedling stage.  The other phase is the leaf blight phase, which is the most common one we see, and causes the most damage.  This bacterium, like a lot of leaf diseases, enters from leaf wounds caused by wind, rain, hail, or mechanical damage.  Once in field, the pathogen overwinters in infected corn residue or other host plant material that are on or near the surface.  Other common host plants are foxtails and barnyardgrass.  The bacteria is then transferred on to new plants by rain splashing and enters through leaf wounds again.  This disease can also be transferred from plant to plant by wind or rain causing the infected leaves to rub against uninfected leaves.  Conditions that favor disease development are warm (>80F) and wet (rain or humidity).  However, Goss’s has been documented to develop in dry conditions. 
               The leaf blight phase is what we should be most concerned about.  Symptoms of this disease are long, water soaked, grayish green lesions with wavy margins that run parallel to leaf veins.  These lesions ooze a sticky exudate that is shiny when held up to the sun.  Eventually, these lesions turn into areas of dead brown tissue.  Within these lesions will be small dark green or black spots commonly referred to as freckles.  An easy way to picture this is imagine placing a small toy brown canoe parallel to the leaf.  Generally, symptoms are most visible and increase after silking, but post maturity identification can be tough.  When going across the field with the combine, be on the look out for small areas that have a darker tan or brown, almost black in some cases, color to the plant or leaves.  These plants can look similar to drought stressed ones but may not be in historic drought areas.  Early infections usually cause the most yield loss, while late infections sometimes cause very little loss.  Yield loss can range from 5% to 50% and is primarily caused by loss of leaf area and premature plant death.  However, Goss’s wilt can cause stalk lodging, furthering the yield loss associated with the disease.
               Its important to remember that this is a bacterial disease, so fungicides have no affect on it.  We have three primary tools to manage Goss’s wilt.  The best tool is hybrid resistance, which has gotten a lot better in the last 10 years.  The second tool is rotation, Purdue University estimates that the bacteria can survive in the soil about 10 months.  Soybeans are a non-host crop but remember to manage your foxtails and barnyardgrass in crop to reduce likely hood of survival.  The last tool is tillage, since the bacteria only survives on residue near or on the surface, burying residue can help reduce disease survival.
               This is a moving disease and there has been documented infections in first year corn fields.  When choosing hybrids this fall or winter, pay attention to what the Goss’s Wilt score are for the hybrids you are picking.  It is better to have disease resistance and not need it than to need disease resistance and not have it.  If you have any questions about Goss’s Wilt or hybrid scoring, give your local Allied Agronomy agronomist a call.

This article is an opinion and is not a base used to make trading decisions.  Allied Companies or the author is not liable for trading decisions made based on the above article.

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