The damage of maize diseases and insect pests is getting worse in China.

In recent years, the planting area of corn in China has increased steadily. In 2014, the planting area of corn in China reached 553 million mu, which has become the largest food crop in China. With the adjustment of planting structure, the change of cultivation techniques and the change of new varieties, maize pests in China have changed obviously, mainly showing the following characteristics.

There are many kinds of occurrence and large area.

In China, there are more than 50 species of corn pests causing economic losses and more than 20 species of common pests. The damage area of corn pests is on the rise. In 2014, the occurrence area of corn pests in China was 837 million mu, and the control area was 782 million mu, recovering 12.51 million tons, but still losing 3.98 million tons.

The harm of frequent pests is aggravated.

The harm of corn borer, underground pests and so on is aggravated. Corn borer is the most important pest in corn production, and the harm of corn borer is on the rise in recent years. In 2014, the occurrence area of corn borer in China was 353 million mu, and the occurrence areas were mainly concentrated in Northeast, North China and Huang-Huai-Hai region, especially in Liaoning, Heilongjiang, Hebei and other provinces.

The main underground pests in corn fields in China are grubs, mole crickets, golden needle worms, ground tigers, spiralis, Spodoptera litura and so on. Since 2008, the harm of underground pests such as grub, mole cricket, golden needle worm and ground tiger in corn field has increased. In 2014, the occurrence area of corn underground pests in China was 112 million mu, including 44.78 million mu of grubs, 27.68 million mu of ground tigers and 24.15 million mu of golden needles. The occurrence areas are mainly in the eight provinces (regions) of Northeast, North China and Northwest China, especially in Liaoning, Shanxi and other provinces.

Some minor pests and emerging pests are seriously harmful.

Peach borer: it only occurs sporadically, but it is common in recent years, especially in Anhui, Shandong and Shaanxi provinces.

Double-spotted firefly beetle: in recent years, the occurrence degree of double-spotted firefly beetle increased obviously. It turns out that the double-spotted firefly is a pest of vegetables and oil crops and rarely harms corn. In recent years, it has occurred more seriously in spring corn areas in northern China, Huang-Huai-Hai summer corn areas and some areas of Shaanxi Province.

Spodoptera litura: with the popularization of no-tillage and stubble sowing and cultivation techniques after wheat harvest, the harm of Spodoptera litura is increasing year by year. In 2014, the occurrence area of Spodoptera litura in China reached 15.16 million mu.

Due to the implementation of large-scale continuous cropping of spring corn in Northeast China for many years, wheat-corn rotation, intercropping and mixed cropping of spring and summer corn were implemented in the main producing areas of Huang-Huai-Hai. In addition, measures such as close planting, no-tillage, straw returning and mechanical cross-area operation are widely adopted in various places, which provide a favorable living environment for the occurrence of insect pests and are conducive to the accumulation, spread and spread of maize insect sources. At the same time, the insect resistance of maize varieties in most areas is poor, if the climate is suitable, corn borer and underground pests will occur more seriously.

With the continuous increase of corn planting area, the occurrence of corn borer will continue to be heavy to large in the northern spring corn region, and the moderate to moderate heavy situation of corn borer in the southwest will continue. In Huang-Huai-Hai summer corn region, the large-scale implementation of straw returning to the field makes the overwintering population of corn borer decrease, the host area of spring sowing decreases, and the population of the first generation of corn borer will decrease. However, the area of summer corn is large, the harm of summer corn in heart and leaf stage is mild, and little control is taken. therefore, corn borer in ear stage will still maintain the trend of moderate occurrence.

The change of farming methods and the popularization of no-tillage and shallow tillage techniques have protected the habitat of underground pests and increased the number of underground pest populations. The harm of grub, ground tiger, golden needle worm, mole cricket, spiral worm, sunflower powder scale and so on will be aggravated. The damage range of Spodoptera litura will continue to expand in the future and become a common seedling pest of summer corn. Except for the serious occurrence in some areas of Hebei, Shandong and Henan provinces, it is unlikely to break out on a large scale in the near future.