Occurrence and control measures of yellow leaf disease of beer

In recent years, the ten diseases of beer in Huanghuakou are becoming more and more serious in northern Jiangsu, which often leads to the decline of yield and quality, and even serious seedling death in some areas. From 1992 to 1995, the author investigated the tissue of 1466.7 and 1866.7 hectares of two-rowed barley planted in the coastal reclamation area of northern Jiangsu and carried out the planting experiment of disease-resistant varieties, and analyzed the relationship between the epidemic of yellow leaf disease and variety, sowing date, cultivation, climate and other factors.

1 the main factors affecting the occurrence of beer yellow leaf disease.

1.1 Disease resistance and tolerance of varieties

1.1.1 the test results of different varieties showed that Gangpi 1 (KA-4B), 7111, 7113 and 6605 had mild disease, strong resistance and strong tiller. 91-Dan2, Gang2 and Suyinmai 3 had an incidence of 40% and 50% before winter, but recovered quickly after jointing and had strong disease tolerance, while Supi 1 was more susceptible, with 193000 ears per 667m2, which was seriously insufficient.

1.1.2 large area disease investigation in 1993, with Su beer varieties as the main body, with Gang 2 varieties as the main body, 178 Su beer varieties were investigated (about 8 hectares per field, 29 diseased fields, accounting for 16.3%, 78 Gang2 varieties, 5 diseased fields, accounting for 6.4%. In 1994, Gang 2 varieties were expanded and Su Beer was compressed. Su Beer 109 yuan, the incidence of 37, the incidence of 34%, Gang2 varieties 187, the incidence of 9, the incidence of 4.8%. In 1995, disease-resistant varieties such as Hong Kong Beer No. 1 (KA-4B) and 91-Dan 2 were planted, Su beer varieties were eliminated, and no yellow leaf disease occurred.

1.2 at sowing time, the main transmission medium of barley yellow leaf disease is Polymyxagramini in soil, and the main infection period is seedling stage 30-40 days after sowing. The earlier sowing is, the higher the probability of virus infection is. The sown area reached 50.8% and 60.1% respectively before October and mid-1993. According to the statistics of the disease situation within two years, 38 early sowing fields with 14.8 hectares were found before October 20, and only 8 fields with 1.56 hectares were sown at the right time from October 26 to 31, while the late sowing wheat in November was very mild. A large number of seeds were sown in the middle of October 1994, which was 5-10 days later than in previous years, and there was almost no disease in 1995.

1.3 stubble and tillage

1.3.1 continuous cropping has a long period of time, and the disease is as serious as in 5N10# field, and Su Beer and other susceptible varieties have been planted in 22S9# field for 4 consecutive years.

1.3.2 less no-tillage dry stubble field is more serious than rice stubble field. Cereal polymyxomycetes are distributed in 5~20cm shallow soil layer. Cotton-wheat interplanting, sending seeds and bean stubble fields mostly adopt the sowing methods of less no-tillage and shallow rake, which have little effect on cereal polymyxomycetes. The incidence of barley yellowing leaf disease in cotton and bean stubble fields accounts for 41.5% and 31.7%, while in rice stubble fields after long-term irrigation and sowing, deep ploughing is carried out. The number of polymyxomycetes was inhibited, and the diseased fields accounted for 20.80%, and the incidence was relatively mild.

1.4 Climate

The soil temperature suitable for zoospore activity of cereal polymyxa was 1.0-15 ℃, and the average soil temperature of local 5cm was lower than 10 ℃ in late November, while the sowing date of barley was late October, and the medium activity before winter coincided with the infection period of wheat seedlings, so the key meteorological factor determining the epidemic of yellow leaf disease was the rainfall during autumn sowing. For example, within 40 days after autumn sowing in 1992, the local average daily temperature was 13.7 ℃ and the rainfall was 224.1mm, which was 3.3 ℃ and 165.9mm higher than that of normal years, with continuous rain. Rotten ploughing and rotten seeds were beneficial to the transmission of media with Rain Water, serious waterlogging damage, weak resistance to wheat seedlings and serious spread of yellow leaf disease. On the contrary, the rainfall in 40 days after autumn sowing in 1993 and 1994 was 1.1mm and 21.5mm, respectively, drought and little rain, and the occurrence of yellow leaf disease was mild.

2 prevention and control measures to control the occurrence and damage of yellowing leaf disease

2.1 good varieties of disease-resistant, high-yield and high-quality beer suitable for planting in this region, such as Gangpi No. 1 (KA-4B), 91-Dan 2, Gang 2, etc., were selected for planting disease-resistant and disease-resistant varieties. It was proved by plot test and large-scale application that the 1000-grain weight was more than 38g, the germination rate was more than 90%, and the yield and quality were favored by planting units and malt manufacturers.

2.2 avoiding premature sowing, such as local postponement of sowing date from mid-October to after October 25, can not only ensure that wheat seedlings overwinter with 5 leaves and turn green for 70 days, but also reduce virus disease. The planting area of cotton stubble wheat should be reduced as much as possible, the cultivation technique of late sowing after cotton should be popularized and the panicle rate should be improved.

2.3 dry stubble (seed, interplanting, bean stubble) pay attention to deep ploughing 20~25cm, and timely excavation of ditches, drainage to reduce stains, to inhibit the spread of cereal polymyxomycetes.

2.4 crop rotation to avoid continuous cropping of beer and wheat, and implement flood and drought rotation or replanting @ # @ 245 crops to reduce the incidence of disease.

2.5 reasonable close planting fertilization should apply the method of two-promoting fertilizer of heavy base fertilizer and light ear fertilizer, which can increase nitrogen fertilizer or spray phosphorus and potassium fertilizer and ABT rooting agent to the diseased field, promote rooting, quickly grow new leaves, and increase the disease resistance of the plant.