The latest control methods of maize brown spot

Corn brown spot is a serious and rapid corn disease in China in recent years, which can cause seed destruction, which occurs in all maize producing areas throughout the country, especially in Hebei, Shandong, Henan, Anhui, Jiangsu and other provinces. It mainly occurs in maize leaves, leaf sheaths and stalks. Let's take a look at the control methods of corn brown spot.

Harmful symptoms

Maize brown spot occurs in maize leaves, leaf sheaths and stalks, and first occurs at the tip of the top leaves, with the most disease spots at the junction of leaves and leaf sheaths, often in dense rows, initially with multi-functional or reddish brown spots, the disease spots are round or oval to linear, the leaf tissue near the uplift is often red, and minor disease spots often gather together, and in severe cases, several or even all of the leaves are covered with disease spots. Large brown spots appeared on the leaf sheath and veins. In the later stage of the disease, the epidermis of the lesion was ruptured, the leaf cell tissue was necrotic, scattered brown powder, the diseased leaves were scattered locally, and the veins and vascular bundles remained like filaments. Stem diseases often occur near the nodes.

Morbidity regularity

Corn brown spot is beneficial to the disease in July and August if the temperature and humidity are high and there are more overcast and rainy days. In the barren land, the leaf color is yellow and the disease is serious. In the land with high soil fertility, corn is strong, the leaf color is dark green, and the disease is mild or even non-pathogenic. Generally speaking, the disease is easy to occur in maize with 8 or 10 leaves, and the disease will not occur again after 12 leaves. In addition, it was investigated that maize varieties with Tangsipingtou components in their parents were susceptible, such as Shendan 16, Shandan 911, Yuyu 26 and so on.

Agricultural prevention and control

The main results are as follows: 1. Thoroughly remove the diseased tissue and dig deep into the soil after corn harvest. Disease-resistant varieties were selected and rotation was carried out for more than 3 years. The planting density was sparsely planted (3500 plants / mu for large panicle varieties and no more than 5000 plants / mu for density-tolerant varieties) to improve field permeability.

2. To apply sufficient base fertilizer and timely topdressing, we should generally apply seedling fertilizer and urea (or nitrogen, phosphorus, potassium compound fertilizer) 10kg / mu at 4-5 leaf stage of maize. If diseases are found, we should apply fertilizer immediately and pay attention to the combination of nitrogen, phosphorus and potassium fertilizer. Compost made by Japanese enzyme bacteria or fully mature organic fertilizer should be applied to topdressing, ploughing and weeding in time to promote the healthy growth of plants and improve disease resistance.

Chemical control

1. Early prevention: the occurrence of corn brown spot can be prevented by spraying 1000 times of 25% trimethoprim or 1500 times of tebuconazole every 667m2.

2. Timely prevention and control: spray stems and leaves immediately with 1500 times of triadimefon wettable powder or with fungicides at the beginning of the disease. In order to improve the control effect, some foliar fertilizers can be added to the solution, such as potassium dihydrogen phosphate, diammonium phosphate aqueous solution (urea in the original and quick-acting nitrogen fertilizer are contradictory), blue Jingdian multi-element micro-fertilizer, strong liquid fertilizer and so on. Combined with the application of quick-acting fertilizer, the spread of the disease can be controlled, and the health of corn can be promoted and the disease resistance can be improved. According to the characteristics of rainy climate, germicidal agents should be sprayed 2-3 times, with an interval of about 7 days, and make up spraying if it rains within 6 hours after spraying.