IV. CONCLUSIONS
There is mounting pressure on farmers to reduce pesticide
use. At the same time, farmers must maintain crop yields and
THE ROLE OF UNCOMPOSTED MATERIALS, COMPOSTS, MANURES, AND COMPOST
EXTRACTS 475
maintain or improve crop quality in order that they can retain
their market share. There is increasing evidence that the use of
uncomposted plant residues, composts, manures, and compost
extracts/teas can help them do this through improvements in
soil health and through direct and indirect control of pests and
pathogens.
In a few documented cases, control of specific pests or diseases
using uncomposted plant residues, composts, or compost
extracts/teas in conventional agricultural or horticultural systems
has been equal to or better than that achieved with synthetic
pesticides. However, for many pests and diseases, the
level of control that has been demonstrated in glasshouse and
field trials is lower than that normally considered acceptable
for conventional growers. Commercial and domestic produce
buyers may find it difficult to accept that the quality and yield
of conventional crops treated in this way are often lower. For
organic growers, who have no access to fungicides or other
synthetic pesticides, uncomposted plant residues, composts,
and compost extracts/teas may provide useful additions to the
range of partial disease control solutions to which they have
access.
Considerable work is required to develop protocols that can
be used to ensure predictable and reliable pest and disease
suppression
or control from organic amendments on economically
important temperate crops in different soil types. Some of the
recent work has been done on tropical or sub-tropical crops
and in different soils and farming systems from those represented
in temperate zones. It will be necessary to adapt the
techniques and protocols successfully developed or being developed
in these climate zones for use in temperate farming
systems.
Many of the recent reports of improved plant growth or successful
disease control using compost teas are based on anecdotal
information or commercially sensitive data held by private
companies. There is a strong need for independent research to
demonstrate the effects of compost teas and to elucidate the
mechanisms behind reports of disease suppression or improved
plant growth. A great deal of the recent work on composts and
compost teas done in the United States has been carried out using
input materials that are prohibited or not readily available in
Europe. Research is required to assess the quality and
diseasesuppressive
properties of composts and compost teas prepared
from input materials that are cost-effective and readily available
to European farmers.
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