Renewable Farming

Agdia test strip

Consultant Bob Streit: Build Goss’ wilt immunity early

Warm, wet and stormy weather is a near-ideal incubator for Goss’ wilt. This bacterial disease hasn’t caused much widespread concern for a couple of seasons, but crop consultants know that the clavibacter michiganesis organisms are widespread across the Corn Belt, and growers need to remain especially alert.

Boone, IA crop consultant Bob Streit is advising his clients:

“In most cornfields, the V8 to V10 growth stage is approaching or already here. In the past few seasons this is when we have been spotting the early signs of this ‘new’ Goss’ wilt. This means the first vascular plugging is beginning and needing to be controlled. I saw this last week for the first time in 2015 in a field around Humboldt, IA and confirmed it using the Agdia test kit. The findings were confirmed again in fields in central Iowa.

“In past seasons we have seen very good yield results from boosting the plant’s immune response against Goss’ wilt by applying the 42 PHI nutritional mix from a ground rig.

“That combination of products keeps the plants alive thru late September, and maximizing yields. The plants stayed green while the kernels plumped up. The yield response typically has been 20-40 bu. better than fields not treated. This sounds like a lot, and it has been. At first we were thinking we should delay spraying until near tasseling,  but then found that the disease progression needs to be treated and impeded immediately, as soon as it’s confirmed.”

What Bob is referring to as a “new” type of Goss’ wilt is that the bacteria are accompanied with a tiny “prion-like” or self-reproducing protein which is still disputed in scientific circles. Bob showed us electron microscope photos of these, which he calls “EM critters” because they can be seen only with an electron microscope. They’re most frequently associated with transgenic crops. Dr. Don Huber first alerted USDA of the presence of these tiny entities in 2011, but the response from officials was slow and dubious. Here’s a link to a PDF of letters from Dr. Huber which explain the early background of this organism, which some label a “biomatrix” because it apparently has no DNA, yet multiplies.  Its presence with Goss’ is significant because it may cause variations in the expression and vigor of the disease. It can also have implications in feedstuffs made from crops.

From a practical standpoint this season, the best diagnostic tools for Goss’ wilt are:

1. Spade to dig corn roots

2. Knife to split root crowns to check for browning and plugging

3. Agdia strip test kit, which can give you a reliable diagnosis for Goss’ presence in about half an hour.  Here’s a link to the Agdia site and test kit specifics. The materials cost of each test in the field is less than $6.

Bob’s mention of 42Phi refers to “42Phi corn,” a nutritional foliar product from ATP Nutrition. It is not a bactericide, but does contain copper along with a balance of other nutrients — all of which are intended to increase cell wall strength and build immunity against the clavibacter organism.  We recall that Dr. Anne Vidaver, University of Nebraska plant pathologist, has told us that the Goss’ bacteria is not extremely aggressive. Thus, a strong immune system or weather conditions unfavorable to spread of the disease can stave it off.

There are probably other broad-spectrum foliars which can help too. The essential idea is that a healthy crop with a strong immune system has the best chance of warding off diseases of all kinds.

We’ve confirmed many times in field trials since 2010 that WakeUP Summer increases absorption and systemic mobility of nutrients in a foliar spray. That also showed up in a 2014 field test where we checked corn yield response in a late-season series of random strip trials using an experimental Goss’ “remedy.” We don’t know the origins of the product, but we sprayed it on replicated strips August 26. Corn was showing external symptoms of Goss’ wilt. Where we sprayed the experimental product by itself, yield improved 10 bushels. On four strips where we added WakeUP Summer, the yield improvement was 17 bushels. Our understanding of this is that WakeUP made the “remedy” more readily absorbed and translocated in the corn’s xylem and phloem system.

Agdia test strip
Two positive red lines indicate Goss’ wilt

Here’s a photo of what the Agdia test strip will show if corn is infected with the clavibacter organism. The top red line indicates the reaction is valid. The bottom red line indicates the presence of the clavibacter organism. The tissue in the sample bag shown here was cut from the stalk.

On June 24, we checked some GMO corn in our neighborhood at the V8 stage and found a positive indication for Goss’ wilt. In this case, we cut “shavings” from the crown of the corn root, which was already turning brown. That indicates plugging with disease organisms. Warm and humid conditions will probably encourage internal development of bacteria and, if the “EM critter” is present, those will reproduce too. Below is the photo of the stalk we dug and split. As the tip of the root crown plugs further, the corn will compensate by developing brace roots above the infected area. However, this compensation can’t keep corn alive and functioning for the full season, which is why so many fields are brown weeks before frost takes them out. The ideal “finish” for corn is a green stalk, green leaves — and a white-husked ear hanging down.


Corn root crown with early signs of plugging