Goss’s Wilt, which has plagued Nebraska corn fields since 1969, has been spotted in Iowa this season.  Iowa farmers are searching for ways to protect yield potential yet this season, as well as avoid the problem in 2012, says ISU Plant Pathologist Alison Robertson.

There are three products that Robertson says she’s heard Iowa corn growers are trying to treat Goss’s Wilt: Procidic, Kocide and Intercept.  Procidic is advertised as a broad spectrum fungicide and bactericide.  However, Robertson isn’t aware of any published data for the effect of Procidic against bacterial diseases or use on corn. Kocide is not labeled for use on corn to manage Goss’s Wilt, so Robertson said it should not be used.  A third product that Iowa growers are reportedly trying is Intercept.  There is very little information available on this product, but it’s reportedly been used in Florida to control citrus canker, which is also caused by a bacterium.

Robertson is monitoring a corn field in Gilbert, Iowa, that had an application of Procidic, as well as an earlier application of Stratego YLD. She says she also will be evaluating fields where Intercept has been applied.  At the end of the growing season, ISU researchers will study the effect of both products on Goss’s Wilt disease development and general plant health of the corn.

“Continuous corn production together with minimum tillage practices have in part contributed to the epidemic of Goss’s wilt we are witnessing in 2011,” says Robertson in a recent Wallaces Farmer article.  “Other factors include susceptible germplasm and stormy weather.”

To avoid Goss’s Wilt in 2012, farmers should keep recommended management practices in mind.  Best practices include growing resistant corn hybrids, using crop rotation and crop residue management.

Guest Blogged by John Toft
CCA, Tekemah, NE

Symptoms of Goss’ Wilt were reported earlier this growing season in Nebraska and Iowa.  With all of the storm damage in these areas, including hail and straight-line winds, it’s no wonder that we’re receiving even more reports now of Goss’ Wilt.  Stalk bruising and leaf shredding provide ways for pathogens to enter the corn plant.  High night-time temperatures, which we’ve also experienced recently, favor the spread of Goss’ Wilt.

Goss’ Wilt causes large lesions that start on the leave’s margins and eventually encompass the entire leaf.  These lesions look very similar to Gray Leaf Spot injury.  One simple, but not fool-proof, way to diagnose the difference is that Goss’ will have a waxy appearance due to the different

pathogens that cause the disease.  Gray Leaf Spot is caused by a fungus while Goss’ is caused by a bacterium, which means Goss’ Wilt cannot be controlled by a fungicide.  Effective control measures include crop rotation, tillage and hybrids that show genetic resistance.  Latham’s 2012 lineup has a number of hybrids with excellent disease packages, so keep this in mind as you make your seed decisions in the coming months.

Seed selection is most likely going to play an even more important role as Goss’ Wilt becomes more prevalent.  Bacterial wilt was first reported in Nebraska more than 40 years ago, and the list of states affected keeps growing.  Goss’ Wilt has been identified in Kansas, Colorado, Wyoming, South Dakota and Iowa.  The disease has also been confirmed in Illinois and Wisconsin, according to a NebGuide article, “Goss’s Bacterial Wilt and Leaf Blight of Corn,” published by the University of Nebraska—Lincoln Extension.