The meltdown of GM farming in Brazil continues, with a plague of Bt toxin-resistant caterpillars giving way to an invasion of Roundup Ready corn acting like a weed in soybean fields

As usual, farmers are paying the price. They are being forced to buy additional herbicides to kill the weedy Roundup-tolerant corn or even to return to hand-hoeing.
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Corn invasion in soybean plantations raises farm costs
By Mariana Caetano
Valor International, 9 Jan 2014
http://www.valor.com.br/international/news/3390626/corn-invasion-soybean-plantations-raises-farm-costs

The troubles faced by Mato Grosso farmers in the current summer crop 2013/2014 started with an outbreak of Helicoverpa earworm, but haven’t stopped yet. Now something unusual is causing them another concern: An invasion of corn into soybean plantations in the state. The so-called guaxo corn — guaxo is a term used for plants that germinate without being cultivated — is considered a weed and has directly affected production costs and putting pressure on farmers’ margins.

The problem, says Nery Ribas, technical manager of Aprosoja/MT, association that represents soy and corn producers in the Mato Grosso state, the largest soybean producer of Brazil, is that most of this corn, which grows spontaneously, is of the Roundup Ready type, the genetically modified Monsanto seed that is resistant to the glyphosate herbicide. "When the farmer applies glyphosate in the crop, it kills weeds, but it does not eliminate the soybean or guaxo corn, since both are RR," he explains. The presence of guaxo RR corn was already seen amid soybeans since the latest harvest, but gathered strength in this crop.

And how has corn ended up mixing with soybeans? The most probable hypothesis is linked to the winter corn crop: During this second corn crop, grains that are dropped off during harvesting, between May and September, remain in the soil and eventually germinate with soybeans, favored by rains in the beginning of the summer crop.

The use of old harvesters can also contribute to the appearance of guaxo corn, says Milton Rego, vice president of Anfavea, auto industry’s trade group. “A new harvester must provide less than 0.5% of mechanical loss, while in [a machine] with 12 years of use, for example, that loss increases to up to 8%. Out of this percentage, it’s assumed that at least 4% of grains germinate,” Mr. Rego says.

Removal of guaxo corn is needed because the plant competes with soybean for water, light, and nutrients. Initial data from a survey by Embrapa Soja point that two to four corn plants by square meter of soybean plantation may reduce by up to 50% the soybean productivity.

There is even a commercial barrier: If grains stay until the harvest, corn will mix with soybeans in the bags, leading trading companies to apply discounts on the amounts paid to farmers, Mr. Ribas, of Aprosoja, says. To weed out the invader, the most effective solution is to invest in the application of a graminicide, a type of pesticide able to eliminate narrow-leaf plants, such as corn, genetically modified or conventional.

"The control is not difficult, but it is costly. I had to apply graminicide three times, with very high dosages," says Elso Pozzobon, a farmer in the region of Sorriso, a Mato Grosso town. Fighting the guaxo corn raised farmers’ total production cost by one bag (or about R$50) per hectare — currently total cost is around 45 bags, or R$2,300 per hectare.

Dissatisfaction with the technology has led Mr. Pozzobon to give up the cultivation of RR corn. "I have already bought conventional seeds for the winter corn season this year. There is a higher expense for farming, but since I will not have to pay royalties for the use of RR, I think that will be offset," he says. The non-genetically modified corn can also sprout spontaneously amid RR soybean plantations, but it is eliminated with the application of glyphosate, along with other weeds.

The case of Alexander Schenkel, farmer in the Campo Verde municipality, is even more curious. He does not cultivate glyphosate-resistant corn, but found several of them in its soybean plots this season. The weed came from nearby farms, and he estimated that at least 40% of his 300 hectares of soybeans have been contaminated. "The 200 to 300 meters at the edge of each plot which borders neighboring properties were the areas that suffered the most, but I came to find guaxo corn even in the middle of plots," he says. The invasion was so intense that it was necessary even to weed them out manually, with hoes.

Fernando Adegas, a researcher at Embrapa Soja, says cross pollination with neighboring farms may have caused the contamination. The pollen of RR corn may travel with the wind and pollinize conventional or Bt (resistant to worms) corn plants. “The guaxo RR corn problem tends to grow throughout the country, because of the cultivation expansion itself,” he says.

Leonardo Bastos, Monsanto chief of marketing, says that cases like Mr. Schenkel’s are localized and the use of graminicide against guaxo corn resistant to glyphosate is “proper of the system.” “Since RR corn was launched in Brazil in 2011, we dedicated a team to follow 3,000 farmers, because we knew there would have to be a change in handling,” he says.

The graminicide, Mr. Bastos adds, also expands the range of herbicides used in cultivations and minimizes the chances of weeds resistant to some chemical element to emerge. “We understand that despite the cost with the graminicide, the revenue generated by the higher productivity of RR corn [4 to 5 bags per hectare, on average] compensates the farmer,” he says.

(Carine Ferreira contributed to this story)