GB/T 23391.2-2026Technical specification for the control of major corn diseases and insect pests - Part 2: Southern corn leaf blight (English PDF)

Foreword

This document complies with the provisions of GB/T 1.1-2020 "Standardization Work Guidelines Part

1.Structure and Drafting Rules of Standardization Documents". Drafting. This document is Part 2 of GB/T 23391, "Technical Specifications for the Control of Major Diseases and Pests of Maize". GB/T 23391 has been published as follows: Part 2.

1.Maize Leaf Spot;

2.Corn Leaf Spot Disease;

3.Asian Corn Borer. This document replaces GB/T 23391.2-2009 "Technical Specifications for the Control of Large and Small Leaf Spots and Corn Borers in Maize - Part

2.Small Leaf Spots in Maize". Compared with GB/T 23391.2-2009, the main technical changes in the "Disease" standard are as follows, except for structural adjustments and editorial modifications.

a) The principles for the prevention and control of maize leaf spot disease have been revised (see Chapter 4, Chapter 4 of the.2009 edition);

b) The phrase "plant disease-resistant varieties" has been changed to "select disease-resistant varieties" (see Chapter 5, Chapter 5 of the.2009 edition);

c) Added the instruction to "pay attention to reasonable layout and rotate planting of varieties with different resistance" (see Chapter 5);

d) Change the requirement from "reducing pathogen sources" to "cleaning up the fields" (see 6.4,

6.1 in the.2009 edition);

e) Change "strengthen cultivation management to improve maize disease resistance" to specific technical measures for "planting," "fertilization," and "irrigation" (see 6.1-6.3). (

6.2 of the.2009 edition)

f) The removal of diseased leaves has been removed (see Chapter 7 in the.2009 edition);

1 Scope

GB/T 23391.2-2026 is the Chinese national standard covering controlling southern corn leaf blight - the disease that destroyed a large part of the United States maize crop in 1970 when a single cytoplasm was planted everywhere, which is why variety diversity is part of the control. It replaces GB/T 23391.2-2009 and has been in force since 1 September 2026. It was issued on 27 February 2026 and has been in force since 1 September 2026, replacing GB/T 23391.2-2009. The document is under the responsibility of the Ministry of Agriculture and Rural Affairs. This page is published from the official record of the 2026 edition; the clause text of a standard this recent is not yet in circulation, and the figures, limits and tables it contains are those of the document itself, delivered in full with the English translation.

This document establishes the principles for the prevention and control of maize leaf spot disease, stipulates the requirements for agricultural, chemical, and biological control, and describes the record-keeping process. Etc. verification methods. This document applies to the prevention and control of corn leaf blight.

4.Prevention and Control Principles Adhere to the plant protection policy of "prevention first, comprehensive control", prioritize the selection of disease-resistant varieties and agricultural control, and combine chemical and biological control. Based on accurate disease prediction and forecasting, implement precise and comprehensive prevention and control measures for diseases.

5.Select disease-resistant varieties In areas where maize leaf spot disease is common or severe, select approved varieties that are suitable for local planting and exhibit high resistance or resistance to the disease. In areas with mild disease, varieties with moderate to high resistance can be promoted for planting. Emphasis should be placed on reasonable planting layout and rotation of varieties with different resistance levels. (Symptoms of small leaf spot) See Appendix A for a description; variety resistance determination shall be conducted in accordance with the provisions of Appendix B.

2 Corn leaf spot disease Published on 2026-02-

27 Implemented on 2026-09-

01 State Administration for Market Regulation The State Administration for Standardization issued a statement.

6 Agricultural control

6.1 Planting Each region should select an appropriate planting density based on local natural conditions, soil fertility, planting patterns, and the characteristics of corn varieties; where conditions permit... In addition, it is also possible to choose to intercrop, alternate, or rotate crops with other non-host plants (soybeans, potatoes, peppers, cabbage, peanuts, etc.).

6.2 Fertilization Apply sufficient base fertilizer, seed fertilizer, and top dressing in stages. At sowing, apply granular fertilizers such as chemical fertilizers and microbial fertilizers in strips or holes. Apply top dressing during the corn's jointing stage or large-scale growth stage. Topdressing should be applied in stages during key periods such as the trumpet stage. When the soil is deficient in phosphorus and potassium, appropriate amounts of phosphorus and potassium fertilizer can be supplemented.

6.3 Irrigation and Drainage Irrigation and drainage in cornfields should be carried out according to local climate characteristics, water requirements of varieties, yield levels, and soil water holding capacity, with key irrigation and drainage periods. The stages are jointing, tasseling, bolting, and grouting. In areas where conditions permit, drip irrigation systems and drainage equipment should be installed to conserve water by using small amounts of water multiple times as needed. irrigation.

6.4 Cleaning up the fields After corn harvest, remove diseased and damaged plant debris from the field, and dispose of the straw properly. Straw used for composting must undergo high-temperature fermentation to kill pathogens. In fields where straw is returned to the field, it should be promptly crushed and deeply plowed back into the soil while the straw has a high moisture content. This promotes the decomposition of plant debris and diseased plant remains in the soil, creating an environment unfavorable to the spread of pathogens. Winter conditions. Avoid using no-till mulching with straw or clearing straw in the following spring for severely diseased fields.

7 Chemical control

7.1 Prevention and control indicators Control measures should be taken when the disease rate in the field reaches 20%.

7.2 Number of applications Apply pesticides when the control threshold is reached. If there is continuous rain or the disease worsens before tasseling, 1-2 additional sprays can be applied, with an interval between each application. 7 days to 10 days.

7.3 Control agents and precautions Foliar spraying should be carried out in the evening using registered chemical agents (see Appendix C for relevant registered agents, dosages, and application methods). If it rains within 24 hours after application, re-spray immediately after the rain.

8.Biological control In the early stages of the disease, apply 24% Jinggangmycin A (dosage and application method are detailed in Appendix C) as a foliar spray in the evening, once. Apply twice, with an interval of 7-10 days, to control corn leaf spot disease.

9.Archival Records Record the date of onset, disease index, type of medication, date of administration, and person administering the medication to establish a traceable file. GB/T 23391.2-2026. Technical Specifications for the Control of Major Diseases and Pests of Maize Part 2. Maize Leaf Spot Disease ICS

15 National Standards of the People's Republic of China Replaces GB/T 23391.2-2009 Technical Specifications for the Prevention and Control of Major Diseases and Pests in Maize Part