Ejeta’s second breakthrough came after he joined the faculty of Purdue University, where his team designed a novel research approach that led to understanding a series of biological phenomena, eventually resulting in the solution of a seemingly intractable problem, the scourge of the parasitic weed Striga. He developed and deployed in more than 12 African countries a series of sorghum cultivars combining drought tolerance with resistance to Striga.

The biological association between Striga and its host plants, of which the sorghum crop is one, is fascinating. Sorghum releases a chemical compound during its development that the Striga seeds (commonly found in large numbers in most African soils) use as an indispensable cue to germinate. Sorghum also releases yet another compound that Striga requires to produce rootlets that allow it to attach to the roots of sorghum plants and eventually rob the sorghum crop of its nutrients.

In essence, sorghum foolishly assists Striga to grow and thrive, leading to the destruction of the sorghum plant. One Striga plant can produce as many as 500,000 new seeds that can potentially remain viable for up to 20 years, resulting in a very quick spread of the weed and massive yield losses of the crop. Ejeta’s research succeeded in designing genetic means to disrupt this relationship and make sorghum resistant to Striga.

The Striga work at Purdue is conducted inside a safely guarded containment facility. Because Striga is easy to spread, Ejeta’s team is required to change clothes to work in the laboratory and must go through decontamination procedures upon leaving. The team is concerned about the possibility of Striga getting to American corn crops, which are also susceptible.

Ejeta’s team was able to develop appropriate and suitable laboratory techniques for identifying the presence or absence of chemical compounds that allowed Striga to germinate and attach to sorghum. Then, using these assays, wild and domesticated sorghum varietals were screened for these compounds.

Those that did not emit the compounds were selected and hybridized with other sorghum types to create a crop cultivar. Ejeta produced about eight tons of the seed at Purdue to distribute across Africa.

Ejeta and his team also devised an integrated Striga management program that improved Striga control and productivity of sorghum. Often, African sorghum farmers disregarded fertilizers because drought made the fertilizer ineffective. Ejeta’s outreach program included water-conservation techniques, which made fertilizers effective again.