Striga asiatica in the U.S.A.

1. Striga asiatica. Habit of plant attached to maize. Photo by D. L. Nickrent
2. Striga asiatica. Close-up of flowers. Photo by D. L. Nickrent
3. Striga asiatica. Close-up of flower bud at time of autogamous pollination. Photo by L. J. Musselman.
4. Striga asiatica. Section through flower bud (at stage in previous picture) showing autogamy. Photo by D. L. Nickrent.
5. Striga asiatica in culture. Proof of autogamy is obtained since flowers set seed in a test tube. Photo by J. Riopel.
6. Striga asiatica. Fruits produce 400-500 seeds each. Photo by M. J. Vasudeva Rao, from "Striga Identification and Control Handbook" (Info.Bull. No. 15, ICRISAT, Patancheru P.O. Andhra Pradesh 502324, India).
7. Striga asiatica seeds compared to maize and Sorghum. Each seed is only 0.2 X 0.3 mm in size. Photo by C. Parker, from "Striga Identification and Control Handbook" (Info.Bull. No. 15, ICRISAT, Patancheru P.O. Andhra Pradesh 502324, India).
8. Striga seed in section while still in fruit. Photo by D. L. Nickrent
9. Striga seed at time of germination. Photo by D. L. Nickrent
10. Strigol and GR-7, two compounds found to induce germination of Striga seeds.
11. Striga asiatica radical with induction of epidermal haustorial hairs by xenognosins. Photo by D. L. Nickrent
12. Xenognosins - the compounds that induce haustorial hairs on Striga seedling radicals.
13. Effect of Striga asiatica on maize. North Carolina. Photo by D. L. Nickrent.
14. Witchweed Quarantine area in North and South Carolina in 1978.
15. Witchweed control. Striga seeds can be induced to germinate in the absence of a host by the gas ethylene. This is called "suicidal" germination. Ethylene can be injected into the soil to remove at least some of the potential pathogens. Ethylene tanks (left) and an ethylene injector (right) are shown. North Carolina. Photo by D. L. Nickrent.