Raising a stink

With China’s corn crop at risk, nation’s scientists wage war on armyworms


Corn prices climb on pest invasion

China’s farming community has a wealth of ancient proverbs to predict weather activity, one being: ‘A storm of black dragonflies, and a drought is coming’. But at the moment the farmers are more watchful for caterpillars, which have been chewing their way through the country’s corn (or maize) harvest.

Named after the way they invade the fields, the caterpillars are known outside China as ‘Fall armyworm’, and are viewed as a scourge for staples such as soybeans, sugarcane and wheat. Their favourite food is corn, and when they feast they can cut crop yields by half.

The migratory insect crossed into Yunnan province from Myanmar in January and was present in 18 provinces at the last count. Officials in China’s agriculture ministry fear they will arrive in the corn heartlands of the northeast this month, and the Beijing News reported on Monday that the pest has been sighted in Shandong, China’s third-largest corn producing province.

In the meantime farmers have been trying to protect their fields. Pre-spraying with chemicals is a preferred option, and the agriculture ministry has identified 25 pesticides for emergency use to control the rapid spread of the armyworms. But many cultivators lack the cash and the know-how to apply the recommended pesticides. Plenty of crop growers have problems even identifying that the armyworm has arrived, some of the newspapers admit.

Because they hail from the Americas, the armyworms lack natural predators within China, although scientists at the Chinese Academy of Agricultural Science think that a local stinkbug can be deployed to strike back. One of its research units has been testing out the bugs and it plans to breed millions more of them to repel the crop-ravaging caterpillars. They can kill as many as 40 armyworm larvae a day by sucking out their body fluid.

The main defence against the invasion is going to come from the weather. The armyworms move into areas with climates similar to their tropical roots, which is why they are heading north as spring turns into summer in China. But that also means their progress should come to a natural halt as the weather cools later in the year, although not before wreaking havoc in the harvest first.

The danger is that this is going to feed inflation at a time when African swine fever is already pushing up food prices. Analysts have struggled to get an accurate picture of how many pigs have perished or been culled as a result of that disease, but consumer prices increased at their fastest pace in 15 months in June, powered by an 18.2% rise in the price of pork.

Corn futures have also breached five-year highs, after torrential rains in the United States, although prices then fell sharply last week on news that more fields had been seeded in the US than the market expected.

China is the world’s second-largest producer and consumer of corn, which is used mostly for animal feed and ethanol. Last year the local harvest wasn’t sufficient to meet domestic demand for the first time in seven years – and that was before the armyworms arrived in Yunnan.

The combination of plague and pestilence could hardly have been predicted, although some believe the severity of the swine flu outbreak will soften some of the impact of lower corn yields, because of reduced demand for animal feed.

Both blights came up for discussion last week at the HSBC Shipping Conference in Hong Kong, where dry bulk bosses lamented how hog flu is hammering demand for soybean imports because millions fewer pigs need to be fed in China.

The armyworms were seen as more of a positive for freight rates, however, with expectations that the Chinese could have to import more corn to make up for the crop lost to the caterpillars.

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