Goss’s Wilt Rears Ugly Head Again in 2015
by Dennis Klockenga, ProfitProAG Consultant
Did it seem like the corn died rather rapidly this year? It did in Central and Southern Minnesota. The weather turned hot and dry for a week and the corn just shut down! Why? Well, there were several diseases that were responsible. Goss’s Wilt seemed to infect virtually every field, while Northern Corn Leaf Blight was more prevalent in Southern Minnesota. It didn’t seem to affect yield as they both infected the crop late in the growing season. However, in some areas it did affect yield.
Goss’s Wilt of corn, Clavibacter michiganensis subspecies nebraskensis is a bacterial disease that causes long and large brown lesions on the leaves that appear water soaked. The lesions have black freckles and when a corn leaf is held up towards the sun, they are quite visible. It was discovered by plant pathologist R.W. Goss from the University of Nebraska. The disease forms a leaf lesion at the onset and then progresses further into the plant where it shuts down the xylem that provides water for the plant. It can also eventually cause death. The newer version of Goss’s Wilt displays a pinkish color on the leaves. It waits for a lesion or wound to form and uses it as an entrance into the plant. Wind or hail can cause wounds to the leaves and/or the stalk, which allows Goss’s Wilt to enter and populate the plant. It typically starts at the top of the plant and works its way down. However it can also start at the bottom and work up. If the infection really gets a foothold, up to 100 bu/A can be lost.
Goss’s Wilt is a weak disease that has become a major headache in a short amount of time! It used to be only a problem in a small part of Nebraska and a few counties in NE Iowa. Now it can be found from the southeastern U.S. all the way into Canada and everywhere in between. So how did it spread so dramatically? It is believed that it may spread via the seed. Seed corn is grown mainly in the Midwest where there are thousands of corn acres. Goss’s Wilt is in the soil and survives in undecomposed corn residue. With the invention of Bt crops, the residue doesn’t breakdown as readily and Goss’s Wilt has a safe haven to overwinter. Soils are becoming more and more biologically dead. With dead soil, pathogens can move in, and since the good biology isn’t there to suppress the bad ones, the pathogens take over.
The conditions that favor Goss’s Wilt include no-till combined with glyphosate application on corn on corn. No-till has the highest risk of Goss’s Wilt infection because there is no soil movement and very little residue break down. If the residue is degraded, it removes the home and environment for Goss’s Wilt. Tillage helps breakdown crop residue by soil contact, which, in turn, reduces Goss’s Wilt.
Glyphosate is a biocide and basically destroys microbial life during the plant’s growing season. By destroying good microbes the pathogens take over. The pathogen likes wet conditions and quickly spreads with a wound created by wind or hail in the leaves or stalk.
The Goss’s Wilt bacteria plugs the sieve plates and stops the xylem and phloem flow, which means that water and minerals are slowed. Hot dry conditions appear to trigger it. If the conditions are right, the plant will shut down in five to seven days. Per Dr. Don Huber, the strong surfactants that are used in glyphosate, combined with other pesticides, nullify the little resistance from Goss’s Wilt. There is also an increased virulence of Goss’s Wilt now versus in the past due to poor soil biology and lack of trace minerals. Virulence means the rate of infection and the amount of damage that it does. According to Dr. Huber, research indicates there is less nutrition in a GMO plant compared to a non-GMO plant.
A few things that can be done to circumvent the disease are to feed soil biology, build up trace elements and increase soil sulfur levels. Building soil biology is critical in keeping pathogens like Goss’s Wilt in check. This can be done by using biological products, adding cover crops in rotation, building organic matter levels and creating a healthy environment for the microbes. It’s also very important to break down corn residue naturally via the soil biology.
Biological products such as Catawater®AG, Bio-ReleaseTM and ProfitCoatTM seed coatings stimulate bacteria and fungi and bring back the earthworms. Earthworms open up the soil by simply moving around. They improve the soil structure, which, consequently, improve water and air movement and create a healthy environment for the plant and the soil. Worms also solubilize tied-up nutrients and their castings are considered perfectly balanced plant food. Earthworms can move through dry and compacted soil because their bodies are slimy, which allows them to move where they want. Words cannot express enough the power of the worm!
Adding cover crops also helps build soil structure, stimulates biological activity and increases earthworm activity. Adding crop diversity is important because it enhances many different microbial species. The more diverse, the more diversity is promoted in soil biology. Cover crops also help to breakup compaction with deep penetrating roots. Roots that are kept in the soil year-round are essential to soil health. Soil microbes feed on the organic acids that the plant roots exudate, which make cover crops vital to a healthy soil. Cover crops also help the microbes to solubilize tied up nutrients in the soil.
Adding trace elements, especially Cu, Mn, Zn, B and Co, is critical in disease suppression. The trace elements are imperative for enzymatic functions in the plant and soil. Sulfur is also vital for healthy soil as it is needed to boost the immune system of the microbes in the soil. Then these microbes pass sulfur into the plant for its immunity.
Breaking down corn residue biologically is of utmost importance for healthy soil. When residue rots and doesn’t biologically break down, it forms aldehydes and alcohols that can be detrimental to soil life. These aldehydes and alcohols create a perfect environment for pathogens to overwinter. Biological degradation of residue also releases nutrients and minerals that are in the residue for the next year’s crop.
Bio-EmpruvTM is a preventative approach to combat Goss’s Wilt. Bio-Empruv contains a blend of biological stimulants, natural fermentation extracts, natural surfactants and microbial metabolites. Itstimulates the plant’s defense mechanisms and improves resistance against many environmental and physiological disorders. It also boosts the plant’s immune system and nutrition. Use a quart per acre of Bio-Empruv as a foliar at stages V6 to V10. In 2015, some tremendous responses were reported from using this product and a 30-70 bu/A increase was not uncommon.
Goss’s Wilt used to be a minor disease, but it has become a force to be reckoned with since our soils lack biology and trace elements. Elevating soil biology, applying trace elements and sulfur helps to keep Goss’s Wilt in check.