Water extracts of fermented mature composts prepared from animal sourc
es (cattle manure and chicken-cattle manure) and a plant source (grape
marc) were tested in growth chamber experiments for their ability to
control leaf grey mould on tomato and pepper plants and grey mould on
grape berries. Disease was reduced by 56-100% by extracts after a ferm
entation that lasted more than 10 days. In some cases, even a shorter
fermentation time was sufficient. Addition of nutrients to the ferment
ing mass did not generally improve disease control. Pasteurization of
the extracts nullified their efficacy in part and only in some cases.
Two bacterial strains isolated from the extracts controlled grey mould
effectively. Dilution of the extracts (25-fold) resulted in retention
of their efficacy only when they were prepared from grape marc compos
t. In an experiment conducted under commercial greenhouse conditions,
extract of cattle manure compost reduced tomato leaf grey mould signif
icantly (p < 0.05) compared with the water control, but superior disea
se suppression was achieved with the fungicide vinclozolin. In another
experiment, involving a heavy natural powdery mildew (Leveillula taur
ica) infestation on tomato leaves, partial control of the disease was
obtained by all extracts tested.