Fungicide Iprovalicarb is a systemic fungicide specific to oomycetes. After spraying, most of the active substance remains on the plant surface, where it forms a deposit that protects the plant from new infections.
A smaller proportion of the active substance is taken up into the plant, after which it is rapidly redistributed to the apical tissues. After drench application, iprovalicarb is rapidly taken up either by the roots or through the plant cuticle and is distributed around the plant in the transpiration stream.
The product affects the growth of germ tubes of zoospores, sporangia and mycelia. It also affects sporulation. Adjuvants (such as oils) enhance the uptake by the plant; this is particularly useful under high disease pressure.
The rate of uptake is also higher under conditions of high temperature and high humidity (including after rainfall and after re-wetting). Iprovalicarb has protectant, curative and anti-sporulant activity. Given its retention on the plant surface, Bayer is recommending its use only in protectant schedules, mixed with contact fungicides, to extend its disease spectrum and to delay/prevent the onset of resistance.
In situations where protective application has not been possible and the first spray of Melody is intended to be curative, it is recommended that subsequent spray intervals be reduced in order to guarantee effective control of the disease.
Field trials were carried out to investigate the post-infection efficiency of curative fungicides against downy mildew on leaves and inflorescences, applying the fungicide either 2 h before artificial infections or at 15%, 30%, 50% and 80% of the incubation process.
Whilst all compounds tested worked well on leaves if applied before infection, iprovalicarb showed the best results in all post-infection treatments, although the infected tissue showed necroses. However there was no sufficient curative effect on inflorescences.
Bayer recommends its use in both resistance management and integrated pest management schemes.