Echinochloa crus-galli (barnyard grass)

Cultural Control

Hand weeding can be effective if adequate labour is available, but when young, E. crus-galli is hard to distinguish from young rice, making hand weeding very difficult.

Bhatia et al. (1990) found that high populations of E. crus-galli in rice fields were due to new seed added every season. Pot and field studies revealed that 97.7% of the seed reserves were exhausted in one season, and by the third season the soil was free of viable seed. Farmyard manure and other organic fertilizers can be major sources of weed seeds, including E. crus-galli, but these lose their viability after being subjected to anaerobic fermentation for one month (Sarapatka et al., 1993).

Deep water flooding (up to 22 cm) can provide good control of E. crus-galli in rice (Williams et al., 1990). Water-sowing, a method of direct-broadcast sowing of rice, began in California, USA, during the 1920s as a cultural method to control E. crus-galli var. crus-galli by continuously-flooded water management (Seaman, 1983).

The use of Azolla in transplanted irrigated rice failed to suppress E. crus-galli var. hispidula, which increased by 226.4%, whereas some weeds were suppressed (Janiya and Moody, 1984). Field and laboratory studies in Asia have indicated that some rice cultivars exhibited strong allelopathic effects against E. crus-galli (Olofsdotter et al., 1996; Chung et al., 1997).

Chung (1995) found that dried lucerne residues inhibited germination and seedling growth of the weeds E. crus-galli, Siegesbechia viridis and Portulaca oleracea, as well as several crops.

Different tillage systems in soyabean and maize fields in northern Italy have been shown to profoundly alter the weed community, with species linked to increased disturbance being annuals, such as E. crus-galli (Sarapatka et al., 1993).

Biological Control

Tsukamoto (1997) describes using virulent isolates of Exserohilum monoceras (anamorph of Septosphaeria monoceras) and Cochliobolus sativus to achieve an approximate 80% reduction in dry matter of different botanical varieties of E. crus-galli.Zhang (1997a) studied optimal temperature and dew-point for the development of E. monoceras on E. crus-galli and E. colonum after inoculation. E. monoceras continues to be the most studied potential biocontrol agent, with Tosiah et al. (2011) evaluating its effects at different leaf development stages and on different varieties of E. crus-galli. In surveys in Malaysia, Tosiah et al. (2009) found E. monoceras, E. longirostratum and Curvularia lunata [Cochliobolus lunatus] among the fungi present on diseased E. crus-galli plants. E. monoceras was consistently found associated with the disease, virulent, stable and with the ability to produce spores profusely in culture, suggesting that it could be used as a biocontrol agent.

Li Jing et al. (2013) evaluated Cochliobolus lunatus as a potential mycoherbicide for barnyard grass, and found that one particular virulent strain was highly pathogenic at the 1- to 2.5-leaf stages, and was safe to rice. It is suggested that this strain could be a potential mycoherbicide for barnyardgrass control in paddy fields in the future. Zhang et al. (2014) found high mortality in E. crus-galli from a strain of Bipolaris eleusines, with no pathogenicity to rice, maize or wheat. Jyothi et al. (2013) report trials with C. lunatus and Alternaria alternata, achieving 100% mortality of the target weed and no effect on rice.

In a review of research progress on mycoherbicides for control of E. crus-galli in rice in China, Zhang et al. (2011) suggest that mass production and formulation technologies have proved to be the major stumbling blocks that hinder bioherbicide development.

A zearalenone derivative extracted from Drechslera portulacae, a pathogen of purslane (Portulaca oleracea), inhibited root length of E. crus galli and Abutilon threophrasti in pot experiments (Kim, 1994; Kim et al., 1994).