U.S. corn and soybean producers face multiple crop disease losses in 2011, warns a team of crop consultants and plant pathologists. They say fungal and bacterial diseases this season could be worse than the billion-bushel plunge in corn yields last fall.

More than 300 farmers heard crop specialists present evidence of that threat — and how to defend against it — at a seminar last week in Des Moines. These specialists say they first recognized an explosion of diseases in Midwest corn and soybeans last summer.

More Disease Problems

Dr. Volker Romheld, director of the Institute of Plant Nutrition, University of Hohemheim in Stuttgart, Germany, says his country’s farmers are running into similar problems that U.S. corn and soybean growers are facing.

“In Germany, we’re running into more crop disease problems, indicating reduced availability of trace elements like manganese and zinc,” Romheld says. “Glyphosate application can induce severe manganese deficiency."

Romheld reports that German farmers are seeing the same rise in disease and crop injury as U.S. farmers, although not as severe.

“In fields with a 10-year history of glyphosate, we see greatly reduced germination of wheat. After only 2 years of glyphosate, there’s little influence,” he adds.

Dr. Don Huber, professor emeritus of plant pathology at Purdue University, says years of research show there is a 500% increase of Fusarium infection of crop roots in a glyphosate environment.

“The more glyphosate that’s applied, the greater is the drop in beneficial soil bacteria, such as pseudomonas,” Huber says. “Glyphosate is a strong biocide.”

Huber says that worldwide research indicates the need for intensified crop nutrition to reduce vulnerability to crop diseases related to genetically engineered traits and years of glyphosate application.

The Des Moines seminar was prompted largely by the crop-disease drama of 2010, organizers say. Last August, no unusual corn or soybean disease problems were evident to USDA crop estimators. On Aug. 12, USDA announced that corn production “is forecast at a record high 13.4 billion bushels, up 2% from the previous record set in 2009.”

However, Iowa-based agronomy consultants and event presenters Bob Streit and Amie Bandy had been scouting corn and soybean fields all summer, and growing more concerned about multiple diseases emerging in corn and soybeans.

Disappearing Yields

In mid-August, they confirmed widespread infestation of a bacterial disease in corn — Goss’s Wilt. For years, this disease had been confined mostly to the western Corn Belt. In summer 2010, a few crop scouts found that it was rippling eastward.

In previous seasons, Streit, Bandy and other consultants had observed that corn had been dying a few days earlier every season as Fusarium and other fungal problems destroyed root structures. In soybeans, molds and Sudden Death Syndrome were spreading from random low patches to kill entire fields.

Streit notes that as fall harvest began, farmers noted that expected yields simply weren’t there. The USDA gradually scaled back yield expectations with each new crop estimate. By Jan. 12, 2011, USDA announced that 2010 corn production “is estimated at 12.4 billion bushels, 5% below the record high production of 13.1 billion bushels set in 2009,” meaning a billion bushels of corn had disappeared from that August forecast.

“Even then, not many economists or agronomists fully comprehended that chronic, recurring diseases were a major factor in slashing 2010 corn crop expectations,” Streit says. “Also, USDA’s August forecast of a 3.43-billion-bushel soybean crop had receded to 3.33 billion by January, as evidence of multiple soybean diseases showed up in harvest reports.”

Those corn and soybean yield losses occurred despite near-ideal harvest weather for most of the Corn Belt, Streit adds.

Streit and Bandy say they and some other consultants and crop pathologists knew what they were looking at in those fields last August because it followed crop pathology and crop nutrition research assembled by researchers like Huber and Bob Kremer, ARS-USDA microbiologist based at the University of Missouri. Huber and Kremer have documented the disease and nutrition impacts of genetically modified crops — and intensive reliance on glyphosate herbicide, which makes up 30% of all herbicide use worldwide.

“By mid-August, we knew we had a serious crop health problem across the entire Midwest,” Streit says. “Many farmers lost $150,000 or more to Sudden Death Syndrome (SDS). Some farmers in Nebraska lost their entire corn crop.”

2010 Problems

Streit and Bandy say there were multiple chronic problems that became clear as the 2010 production season drew toward a close:

  • Early root rots were common, primarily Fusarium, which crippled root exploration.
  • Micronutrient deficiencies were showing up in corn and soybeans.
  • Some corn hybrids proved genetically vulnerable to molds.
  • Soil microlife was skewed to favor Fusarium molds. Beneficial bacteria — needed to make trace elements such as manganese available for resistance to diseases — had disappeared.

Glyphosate Issues

Streit says that Fusarium mold dominance on roots is one consequence of heavy, repeated applications of glyphosate. Streit says this chemical, based on a phosphorus molecule, can kill beneficial bacteria. Crops exude part of the applied glyphosate through their roots into soil, where it shifts the balance of microlife toward the fungal side, he says.

The Iowa consultant adds that glyphosate is a strong chelator of every micronutrient needed by crop immune systems, from boron through manganese to zinc. The micronutrients are also essential for defense against environmental stresses.

Streit says that the effects of glyphosate, compounded over many years, were hitting in the 2010 season when the crop was already struggling with excess moisture, soil compaction and disease organisms harbored in previous years’ crop residue on the soil surface.

At the Des Moines seminar, Huber and other crop scientists from Germany, England and Canada explained that some of the GMO and glyphosate impact can be remediated by extra crop nutrition and enhancing soil biological activity.

They outlined these basics to help farmers buffer the disease threats in GMO crops in 2011 and beyond:

  1. Get soil tests that include micronutrients as well as nitrogen, phosphorus and potassium. However, results showing sufficient or even high readings of manganese, boron, zinc and other traces in the soil may be misleading if the farm has a long history of glyphosate applications. Many trace elements may be chelated with glyphosate in the soil and unavailable to the crop.
  2. Take measures to rebuild soil biological activity, especially the beneficial pseudomonas bacteria and crop-friendly Tricoderma fungus. Several live microbial products are available to farmers.
  3. Early in the season, send entire plant samples to a reliable laboratory for tissue testing. Low readings of trace elements signal a vulnerable crop.
  4. Foliar feeding trace elements can help remediate the chelating effect of glyphosate. Because of the urgency for adequate trace elements, seek out products with the ability to rapidly translocate trace elements.

Crop consultants and farmers at the seminar reported that many farmers saw no significant disease in their 2010 corn and soybean crops. Their corn leaves and stalks remained green until the first frost, with a white husk over a completely filled ear.

Streit says this was common among the roughly 10% to 15% of Midwest farmers who haven’t switched to GMO hybrids and varieties, and those who have focused on building biological life in their soils.