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an engineered super fungus to control weeds

The article below shows an interesting but very dangerous strategy for weed control without chemicals. The history of genetics is well endowed with examples of super pathogens that recombine and mutate to extend host range. There must be liability associated with the potential destruction caused by such inventions. Even the solution of introducing genetic remedies into the crops effected by super fungi provides cold comfort to organic farmers or unprepared neighboring farms.
Nature Biotechnology
October 2002 Volume 20 Number 10 pp 1035 - 1039

Engineering hyper virulence in a mycoherbicidal fungus for efficient weed control
Ziva Amsellem1, Barry A. Cohen1,  & Jonathan Gressel

Agents proposed for biocontrol of major weeds in arable row-crop agriculture have not met expectations because an evolutionary balance has developed between microorganism and weed, even when the mycoherbicide is used inundatively at very high levels (>104 spores/cm2). Sufficient virulence can be achieved by transferring genes to the microorganism, tipping the evolutionary balance. Virulence was increased ninefold and was more rapidly effected; furthermore, the requirement for a long duration at high humidity was decreased by introducing NEP1 encoding a phytotoxic protein, to an Abutilon theophrasti–specific, weakly mycoherbicidal strain of Colletotrichum coccodes. The parent strain was at best infective on juvenile cotyledons of this intransigent weed. The transgenic strain was lethal through the three-leaf stage, a sufficient time window to control this asynchronously germinating weed. Strategies of coupling virulence genes with fail-safe mechanisms to prevent spread (due to broadened host range) and to mitigate transgene introgression into crop pathogens could be very useful in the biocontrol of major weeds in row crops.