Striga asiatica (herb)
S. asiatica attacks important crops such as: corn, sorghum, sugar cane, and rice. It is also known to parasitize certain weedy grasses. S. asiatica robs nutrients and moisture by tapping directly into a host's root system. The host expends energy supporting S. asiatica growth at its own expense. S. asiatica will grow in the presence of grassy weeds as well as grass host crops, so cotton, peanut, or soybean fields-along with home gardens or idle land-may harbor this species (APHIS, 2000).
Federal and state quarantine and eradication programs have been able to greatly reduced the area of S. asiatica infestation since 1955 but with at a great economic cost (CDFA, 2006).
Research conducted by Mohamed et al. (1998) suggests evaluating the efficacy of ethylene treatment before application. Their research has shown that if seeds buried in the soil have moisture content above their threshold, then application of ethylene will not cause suicidal germination. The authors state that, "One does not need to condition the seed to observe readiness to germinate but need only measure moisture content. When the seeds reach a certain moisture content they will fail to germinate, so inducing this high moisture content by pre-watering the soil in irrigated fields or by delaying the sowing date in areas with a long rainy season could be a strategy for an integrated approach to control. This could easily be managed if weed scientists or extension officers measured the seed moisture content. When certain moisture content is reached, they can recommend a sowing date for farmers in Striga-infested areas (Mohamed et al. 1998).
Biological: Elzein and Kroschel (2004) have found that the fungal pathogen Fusarium oxysporum abbreviated as Foxy 2, isolated from diseased S. hermonthica plants from Ghana, proved to be highly pathogenic against all developmental stages of the parasite, including seeds. Foxy 2 was found to be very effective in reducing the seedbank of S. asiatica by destruction of the seeds and prevention of emergence and subsequent reproduction, however, no severe disease symptoms or death were observed on the emerged S. asiatica shoots but its potential application as a biological control agent for this species is still a possibility for early developmental stages of S. asiatica (Elzein and Kroschel, 2004).