Alternative methods to synthetic chemical control of Cynodon dactylon (L.) Pers. A systematic review

Cynodon dactylon (L.) Pers. is one of the worst agricultural weeds and invasive species in the world, being widely established in many countries. Despite its impact on agriculture and the growing awareness of authorities and consumers about the consequences of synthetic herbicides, alternative control methods for this weed have been poorly reviewed. A systematic review of the literature published over the last 50 years was used to assess the most studied control methods of C. dactylon (excluding synthetic herbicides) and to summarize the trends and knowledge gaps. The major findings are as follows: (1) the number of publications that studied alternative methods to synthetic chemical control in C. dactylon management has been increasing exponentially since 1972; (2) most of the studies were made under controlled conditions (57%) and lack observations under real production conditions; (3) most of the field experiments were carried out in Asia (42%), under temperate subtropical and arid climates; (4) the publication of articles studying allelopathy stands out significantly (50% of the papers found), with two species from the Poaceae family, rice (Oryza sativa L.) and sorghum (Sorghum bicolor (L.) Moench), showing very high allelopathic inhibitory effects (often above 80%), especially under open field conditions; and (5) preventive soil tillage is the most studied treatment among indirect weed control treatments, and although there is a high risk of propagation, the results indicate that tillage can significantly contribute to control C. dactylon, when compared to no-tillage treatments. Further research is needed to optimize treatments and methods so that they can be applied by farmers under real production conditions.