The Toothpick Project: commercialization of a virulence‐selected fungal bioherbicide for Striga hermonthica (witchweed) biocontrol in Kenya

Abstract

The high‐level view of global food systems identifies three all‐encompassing barriers to the adoption of food systems solutions: knowledge, policy, and finance. These barriers, and the siloed characteristics of each of these, have hindered the development and adoption of microbial herbicides. How knowledge, policy, and finance are related to the Toothpick Project's path of commercializing a new bioherbicide, early in the scope of the industry, is discussed here. The Toothpick Project's innovation, developed over four decades and commercialized in 2021, uses strains of Fusarium oxysporum f.sp. strigae selected for overproduction and excretion of specific amino acids, killing the parasitic weed Striga hermonthica (Striga or witchweed), Africa's worst pest threat to food security. Historically, bioherbicides have not been a sufficient alternative to the dominant use of synthetic chemical herbicides. To be used safely as bioherbicides, plant pathogens need to be host specific, non‐toxic, and yet sufficiently virulent to control a specific weed. For commercialization, bioherbicides must be affordable and require a sufficient shelf life for distribution. Given the current triple storm encountered by the chemical herbicide industry (herbicide‐resistant weeds, lawsuits, and consumer pushback), there exists an opportunity to use certain plant pathogens as bioherbicides by enhancing their virulence. By discussing barriers in the scope of knowledge, policy, and finance in the development of the Toothpick Project's new microbial bioherbicide, we hope to help others to anticipate the challenges and provide change‐leaders, particularly in policy and finance, a ground level perspective of bioherbicide development.This article is protected by copyright. All rights reserved.

Parasitic Plants—Potential Vectors of Phytopathogens

“…and Striga spp. The most exploited is probably Fusarium oxysporum , whose highly specific strains are efficient selective control agents for both the germination and growth of Striga [ 144 , 145 , 146 , 147 ], but also Orobanche spp. [ 148 ].…”

“…There are hundreds of reports on the isolation and application of such fungal isolates as biocontrol agents on root parasitic plants, underlining the importance of such pathogens for food production security, especially in the poorest regions of Africa. One major advantage of such a bioherbicide is the possibility to propagate without any special equipment, so it is readily available to farmers in distant and poor regions [ 147 ]. However, most wild strains of putative phytopathogens are insufficiently virulent to be effective bioherbicides.…”

The future of microbial bioherbicides

“…The meeting was organized into twenty‐two 50‐min presentations with ample time for discussion. Sixteen of the articles in this issue are from conference participants 2–17 . Four related articles from non‐participants are also included 18–21 .…”

“…Charudattan and coworkers provide a review on the use of viruses as bioherbicides and a research article on the only commercialized viral bioherbicide, a product for control of the noxious weed tropical soda apple 6,7 . The development and commercialization of a genetically selected strain of Fusarium oxysporum for control of Striga hermonthica (witchweed), a devastating, parasitic weed in Africa, is described 8 . Its improvement as a seed coating for control of this weed in maize is covered in another research article 9 .…”

“…Sixteen of the articles in this issue are from conference participants. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] Four related articles from non-participants are also included. [18][19][20][21] The article by Duke gives the rationale for the meeting, discussing the many microbial bioherbicides that have failed and detailing the technical and economic reasons for lack of success.…”