Occurrence of wheat and barley sheath blight and control recommendations

According to surveys by the forecasting stations of each county (city, district), wheat and barley sheath blight has now occurred widely and will enter the peak damage stage. All localities must seize the appropriate timing and promptly organize the broad masses of farmers to carry out control.

I. Occurrence situation and trend analysis

The characteristics of wheat and barley sheath blight occurrence this year: First, the occurrence period is normal. Due to the low temperatures last winter and this spring, wheat seedlings grew weakly, which was unfavorable for the occurrence of wheat and barley sheath blight. The earliest detection in the whole city was in Xiangshui in early mid-February, and large areas were detected in late February and early March. Second, the general incidence rate and disease severity are slightly lighter than the same period last year. According to a systematic survey in Xiangshui on March 15, @#@245@#@ the diseased plant rate was 21.25% (7-35.5%), and the disease index was 4.25 (1.4-7.1); according to a systematic survey in Dongtai on March 15, the wheat diseased plant rate was 2% (0-4%). A survey of 165 fields in the whole city from March 16-18 found that among 143 wheat fields, the diseased field rate was 40.6%, and the diseased plant rate was 3.25% (0-62.5%); among 22 barley fields, the diseased field rate was 31.8%, and the diseased plant rate was 0.73% (0-7%). Third, there are relatively large differences among different regions and different cropping sequences. For the whole city, the northern region is more severe than the central and southern regions, dry-crop stubble fields are more severe than rice stubble fields, and wheat is more severe than barley. A survey of 20 fields in Xiangshui on March 18 found that among 10 dry-crop stubble wheat fields, the diseased field rate was 100%, and the diseased plant rate was 28.5% (4-62.5%); among 10 rice stubble wheat fields, the diseased field rate was 70.0%, and the diseased plant rate was 4.6% (0-18%). A survey of 22 fields in Funing found that among 17 wheat fields, the diseased field rate was 17.7%, and the diseased plant rate was 1.85% (0-9.5%); among 5 barley fields, the diseased field rate was 20%, and the diseased plant rate was 1.4% (0-7%). A survey of 26 fields in Dongtai found a diseased field rate of 30.8% and a diseased plant rate of 0.85% (0-7%). In places such as Sheyang and Tinghu, however, only scattered cases were detected.

Wheat has successively entered the jointing stage, and sheath blight will also enter the key period of stem invasion and damage. As temperatures rise, disease development will be accelerated. If rainy weather occurs in the future, it will be even more favorable for disease development. It is expected that wheat and barley sheath blight this year will be at a moderate occurrence level, with severe occurrence in some areas. Some fields with high density, large populations, good growth and dense weeds may have the possibility of severe outbreaks.

II. Control recommendations

1. Make full use of agricultural measures to create environmental conditions unfavorable for the occurrence and development of the disease. All localities should make full use of agricultural measures, clear ditches and improve soil moisture management, improve drainage and waterlogging reduction capacity, and lower field humidity; promptly remove field weeds to improve light penetration; increase application of phosphorus and potassium fertilizers to improve plant disease resistance, thereby inhibiting the occurrence and development of the disease.

2. Promptly organize chemical control to control disease development. Applying chemicals at the wheat jointing stage is key to controlling disease development, preventing stem invasion and reducing damage. All localities should seize the jointing stage from late March to early April. For fields where the sheath blight diseased plant rate reaches 20% or more or where stems show scattered disease, spraying should be carried out immediately for control. For chemicals, 40% Bote wettable powder can be selected at 30-40 grams per mu or 20% jinggangmycin powder at 50 grams per mu, mixed with 50 kg of water for coarse spraying. When applying chemicals, aim at the middle and lower parts of the plants and spray evenly and thoroughly. The number of applications should be appropriately increased according to disease development. For fields with early disease onset, severe disease, and still relatively rapid disease development after application, chemicals must be applied 2 times or more, with an interval of 7-10 days between each application.