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Acta Prataculturae Sinica ›› 2025, Vol. 34 ›› Issue (12): 195-205.DOI: 10.11686/cyxb2025094

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Effect of co-attack of spring black stem and leaf spot disease and aphids on the yield and forage value of alfalfa

Mei-ting BAI1(), Ying-de LI2, Qian-hua CHEN3, Yan-li FENG1, Hai-ming FENG4, Ting-yu DUAN2   

  1. 1.Gansu Open University,Lanzhou 730030,China
    2.State Key Laboratory of Herbage Improvement and Grassland Agro-ecosystems,Key Laboratory of Grassland Livestock Industry Innovation,Ministry of Agriculture and Rural Affair,Engineering Research Center of Grassland Industry,Ministry of Education,College of Pastoral Agriculture Science and Technology,Lanzhou University,Lanzhou 730020,China
    3.Shaanxi Construction Technology Institute,Xi’an 710119,China
    4.Jiuquan Open University,Jiuquan 735000,China
  • Received:2025-03-21 Revised:2025-04-21 Online:2025-12-20 Published:2025-10-20
  • Contact: Mei-ting BAI

Abstract:

Pests and diseases significantly constrain Medicago sativa (alfalfa) production. Spring black stem disease, caused by the fungal pathogen Phoma medicagonis and pea aphid (Acyrthosiphon pisum), is widespread in alfalfa-growing regions of China. However, the impact of the combined occurrence of this pathogen and the aphid on alfalfa yield and quality remains unclear. To address this knowledge gap, we conducted a field experiment at the Jingtai Field Scientific Observation and Research Station of Grassland Agro-Ecosystems, Lanzhou University. The treatments included spring black stem inoculation, pea aphid disease infestation, combined spring black stem disease inoculation and pea aphid infestation, and spraying with β-cyfluthrin solution. Naturally grown alfalfa served as the control. The results show that the incidence and disease index of spring black stem disease in the pathogen treatment and pathogen+aphid treatment groups reached 54.67%-82.67% and 20.93%-40.93%, respectively, significantly higher than those in the control and insecticide-protected groups. Compared with the control and insecticide groups, the pathogen treatment group and pathogen+aphid treatment group showed decreases in alfalfa yield (decreases of 20.87%-22.17%). Pests and diseases had a greater impact on the nutrient contents and feeding value of alfalfa leaves than on stems or the entire aboveground part, especially in the pathogen+aphid treatment group. Compared with the control, the pathogen treatment group showed significantly reduced calcium and sulfur contents in the leaves and significantly increased potassium content (P<0.05). The protein content in alfalfa leaves was significantly lower in the pathogen treatment group, aphid treatment group, and pathogen+aphid treatment group than in the insecticide group. The monosaccaride content in leaves was higher in the pathogen+aphid treatment group than in the control (P<0.05), and the acetic acid and lactic acid contents in alfalfa leaves were lower in the pathogen+aphid treatment group than in the pathogen-only treatment group (P<0.05). The results of this study provide a theoretical basis for assessing alfalfa crop losses caused by spring black stem disease and pea aphid, and offer theoretical guidance for the development and refinement of pest and disease control strategies.

Key words: loss evaluation, disease and insect pests, feeding value, disease and insect pests management