Corn stem borer. Harmfulness and control measures

Corn is a strategically important crop for the Stavropol Krai, grown in large quantities. It is also grown on private plots. Proper agricultural practices, carefully selected crop protection products, and timely pest control enable farmers to achieve high yields. Specialists from the Stavropol branch of the Russian Agricultural Center discuss one such pest today.

Pest characteristics. The corn stem borer is a polyphagous pest common in various regions. Optimal conditions for its development include high humidity and air temperatures above 20°C. From June to mid-July, female moths lay eggs on the middle and upper leaves of corn plants. The caterpillars then disperse to adjacent leaves and reach the main shoot. A single female lays approximately 250-400 eggs.

Caterpillar development lasts about 14 days. During the first few days, they live on the surface of plants, damaging leaves by making holes in them and eating out male flowers in panicles. They then penetrate petioles and stem tips.

Caterpillars chew tunnels in the stems with holes exposed to the outside. They also make tunnels among the grains. Several caterpillars can live in a single stem or ear. Caterpillars of the first three generations feed on the soft tissue of leaves and the spikelets of the panicle; caterpillars of the third and fourth generations consume stem tissue and young grain. The lifespan of caterpillars is 15-60 days.

Symptoms of corn damage include yellowing of the central and leaf veins with the presence of excrement, stem breakage, delayed flowering, reduced leaf and internode size, panicle damage, and poor pollination.

Harmfulness. The pest disrupts the supply of nutrients to the ears, and severely damaged stems easily break. This leads to reduced yield and seed quality, and the ears often become susceptible to fusarium, gray mold, and mildew. The effective pest control (EPC) is achieved at a population density of 5–6 caterpillars/m².

Prevention and control measures:
deep plowing;
weed control;
harvesting corn promptly;
chopping up post-harvest residues immediately after harvesting;
using resistant corn hybrids;
treating crops with insecticides.

In addition to the above-mentioned measures, the Stavropol branch of the Russian Agricultural Center also offers agricultural producers an effective biological method: the release of the entomophage Trichogramma. This insect is grown in the branch's laboratories and is as effective as chemical pest control.