Does corn brown spot affect yield? A detailed guide to prevention and control methods

Corn is an important food crop and is widely grown around the world, but during its cultivation it is often attacked by diseases, among which brown spot is a corn disease that has occurred rather severely in our country in recent years. So, what are the prevention and control methods for corn brown spot? Does it affect yield?

1. What are the prevention and control methods for corn brown spot?

1. Agricultural measures

(1) After the corn harvest, thoroughly remove diseased plant residue and tissues, deep plow the soil, apply sufficient base fertilizer, and topdress in a timely manner. Generally, seedling fertilizer should be applied at the 4-5 leaf stage of corn, with 10-15 kg/mu of urea (or nitrogen, phosphorus, and potassium compound fertilizer). If disease is found, topdressing should be carried out immediately, taking care to balance nitrogen, phosphorus, and potassium fertilizers;

(2) Select disease-resistant varieties and implement crop rotation of more than 3 years;

(3) Apply compost fermented with Japanese enzyme bacteria or fully decomposed organic fertilizer, topdress and hoe weeds in a timely manner, promote robust plant growth, and improve disease resistance;

(4) Plant at an appropriately sparse density (3500 plants/mu for large-eared varieties, and no more than 5000 plants/mu even for density-tolerant varieties) to improve field ventilation and light penetration.

2. Chemical control

(1) Early prevention

At the 4-5 leaf stage of corn, spray the leaves with a 1000-fold dilution of 25% triadimefon or a 1500-fold dilution of 25% tebuconazole per 667 square meters, which can prevent the occurrence of corn brown spot.

(2) Treatment after disease onset

When corn first shows symptoms, immediately spray the stems and leaves with a 1500-fold dilution of 25% triadimefon (triadimefon) wettable powder or spray with a fungicide for fungal diseases. To improve the control effect, an appropriate amount of foliar fertilizer may be added to the spray solution, such as monopotassium phosphate, diammonium phosphate aqueous solution, Blue Crystal multi-element micro-fertilizer, Zhuanghan liquid fertilizer, etc. Combined with topdressing of quick-acting fertilizers, this can control the spread of the disease, promote robust corn growth, and improve corn disease resistance. According to the rainy climate characteristics, fungicide sprays should be applied 2-3 times at intervals of about 7 days; if it rains within 6 hours after spraying, re-spray after the rain.

2. Does corn brown spot affect yield?

Corn brown spot mainly damages corn leaves, leaf sheaths, and stalks. In the early stage of disease, round or oval yellow spots form on diseased parts. Many small spots usually connect to form alternating horizontal band-like yellow patches, and the main leaf veins often have interrupted strip-shaped black spots; later, the diseased tissue gradually turns brown or dark brown and merges into large, irregular patches, often causing the diseased parts to die, which has a great impact on yield. In the field, it often occurs mixed with diseases such as corn southern leaf blight and curvularia leaf spot.

For corn brown spot, the policy of “prevention first, treatment as auxiliary” should be followed, with prevention and control starting from agricultural practices, to achieve twice the result with half the effort. If disease has already occurred, chemical control measures should be taken immediately.