Analysis on Distribution and Change of Weed Community in Winter Wheat Field in Henan Province

In the past 10 years, the weed communities in the winter wheat fields in Henan Province have changed significantly. The objective of this study is to clarify the succession of weed communities in the six major planting areas in Henan Province, analyze the reasons of weed succession, and to provide a theoretical basis for the establishment of accurate control strategy of weeds in winter wheat fields.

A total of 378 plots in 17 cities of Henan Province were sampled from November to December in the 2023 to investigate the weed species and weed number in winter wheat fields, compared with the results of 2013, the weed community composition in six major planting areas of winter wheat fields in Henan Province was determined, and the weed community change law was analyzed.

The characteristics of weed communities in winter wheat fields in Henan Province were: (1) Gramineous weeds developed rapidly, Aegilops tauschii, Lolium multiflorum, Bromus japonicas, and Alopecurus myosuroides gradually spread from the local area to the whole province, almost covering the whole province major planting areas at present. Among them, A. tauschii and B. japonicus mainly occurred in dry-stubble wheat fields. In 2013, 14th, 15th, 27th and 35th relative abundances of the four weeds were ranked, respectively, but relative abundances ranked 2nd, 5th, 8th and 15th, respectively, in 2023. (2) Galium aparine and Veronica persica had always been the dominant broad-leaved weeds in winter wheat fields in Henan Province, with relative abundance of 26.89% and 10.68% in 2023, respectively. In the past 10 years, two surveys showed that the comprehensive relative abundance of G. aparine ranked first, G. aparine caused great damage in both dry-stubble wheat field and rice-stubble wheat field, and V. persica had risen from 6th to 3rd. (3) G. aparine, A. tauschii, V. persica, and Descurainia sophia became the dominant weeds in winter wheat fields in Henan Province. In 2013, only G. aparine and Capsella bursa-pastoris had relative abundance of more than 10%, which was 17.38% and 10.92%, respectively, but in 2023, the relative abundance of G. aparine, A. tauschii, V. persica, and D. sophia exceeded 10%, which was 26.89%, 13.45%, 10.68%, and 10.65%, respectively. (4) The damage of regional dominant weeds was also serious, such as Lamium amplexicaule, Raphanus raphanistrum, Malachium aquaticum, Euphorbia helioscopia, Lithospermum arvense, and Geranium carolinianum. In addition, regional harmful weeds such as Lapsana apogonoides, Mazus japonicus, and Alopecurus aequalis were mainly distributed in rice-stubble wheat fields.

The changes of the weed communities in winter wheat fields in Henan Province are mainly caused by the changes of farming systems, the spread and invasion of malignant weeds and the development of weed resistance. Cross-regional operation of combine harvester and human unconscious carrying and spreading are also important factors to promote the change of weed community. Therefore, in the prevention and control of weeds in winter wheat fields in Henan Province, the integrated weed control strategies, such as combining chemical herbicides with agronomic measures, the precise selection of herbicides according to the field grass phase in different planting areas and using herbicides with different mechanisms, should be promoted.