DOES THE RESEARCH ON PLANT PHENOLS HOLD OUT PROSPECTS IN INTEGRATED PLANT PRODUCTION? – PLANT NUTRITION / PLANT PRODUCTION

There is a wide array of plants, differing in their primary and secondary metabolism, which are attacked by numerous pathogens and herbivores, which are cultivated under different environmental conditions, and which are managed in different ways, so that there is no simple and easy answer to the questions raised for the discussion.
A few general remarks, however, should be allowed:

• Reducing the needs for external inputs, which may negatively affect agro- and adjoining ecosystems, is one crucial point for sustainable agriculture.
  At present, there are increasing problems in finding pesticides which are ecologically "safe" and which do not yet pose problems with resistance of the target organisms.
  There are cases where we do not have any more an approved product which could control resistance pathogens of herbivores, and cross resistances are increasing.

  It has to be decided up to which extent reduced carbon (and thus energy) has to be invested by the plant in defence mechanisms and which may thus be not available to yield formation, and to which extent the necessary energy may be provided in form of biocides or other "external inputs".

• Knowing still more about the plants defence mechanisms (which are frequently related to phenol metabolism) may assist in looking for treatments, cultivars, of "genetically engineered" cultivars which enable the plants to cope with attacks of certain pathogenic organisms.

• It has to be kept in mind, though, that as with almost any chemical treatment, there will be on the long run (on an ecologically relevant time scale), at least one pathogen which is able to overcome, at least partially, these defence mechanisms.
  It is likely that monogenic resistances are more easily broken down than multigenic ones.
  Selection pressure is lower if there is a multigenic intermediate resistance and thus the tendency to select for resistant pathogens is lower.
  It makes ecologically more sense to have plants which are moderately

International Symposium on Natural Phenols in Plant Resistance

H. Goldbach

https://doi.org/10.17660/ActaHortic.1994.381.119