Agriculture Reference
In-Depth Information
Application technology can have a signifi cant impact on the effi cacy of BCAs.
Unfortunately, this has often been neglected in the past, especially for the application
of BCAs to aerial microbiomes, resulting in poor effi cacy. Targeted delivery, deposition
and coverage of the infection court are essential for good disease control. In laboratory
experiments, Scherm
et al
. (2004) reported signifi cant activity of the commercial
product Serenade (
B. subtilis
QST713) against blueberry fl ower infection by
Monilinia
vaccinii-corymbosis
. However, disease suppression was unsatisfactory when the
B. subtilis-
based product was applied in the fi eld with a standard sprayer. This was
likely due to low and variable coverage of the stigmatic infection court, which presents
a diffi cult spray target. In a recent laboratory study, air-assisted electrostatic spraying
signifi cantly increased deposition of
B. subtilis
QST713 and coverage on the stigmatic sur-
faces of detached blueberry fl ower clusters compared to conventional hydraulic spraying
(Scherm
et al
., 2007). The increased deposition and coverage together with the excellent
bacterial survival in the formulated product bodes well for electrostatic application of the
product for disease control in the fi eld.
One of the major economic hurdles in the commercialisation of BCAs is in risk
assessment of toxicity and environmental impact of the organism, and its formulation
(Brimmer & Boland, 2003; Winding
et al
., 2004; Scherwinski
et al
., 2007). Extensive
trials are essential to generate data for registration purposes to show that potential com-
mercial BCAs are safe both to humans and to other non-target organisms. Quality and
effi cacy data as well as additional technical protocols are also required by the registration
authorities. All this can be extremely time-consuming and very expensive to generate as
well as the cost for the assessment process itself. High registration costs have clearly been
responsible for delaying or preventing the commercial development of BCAs in the past,
especially by small-medium-size enterprises (SMEs) which are the main producers of
BCAs. This has led to a large number of products appearing on the market which actually
work by controlling plant pathogens but are claimed to be soil conditioners, plant-growth
promoters or biofertilisers that do not require registration. However, without toxicologi-
cal and effi cacy data, safe use cannot be assured and consistent disease control and crop
growth are not always observed (Cook
et al
., 1996). Some regulatory authorities have
recognised these problems and are encouraging legal registration and use of BCAs in a
number of ways. For example, in the United Kingdom, the Pesticides Safety Directorate
(PSD) offers a lower charging scheme for BCAs than chemicals, and in the United States
the EPA offers a more fl exible case-by-case and/or 'fast-track' approach. Despite the
introduction of these schemes, these problems still remain. However, some BCAs have
gone through the entire registration process and are available for sale and use in a number
of countries (Tables 3.1-3.3).
Large-scale use of commercial products is still limited because of variability and
inconsistency in terms of disease control. Coupled with a very competitive market with
chemical pesticides, manufacturers of BCAs are fi nding it increasingly diffi cult to make
suffi cient profi t from sale of commercial products to maintain the costs of registration.
Unfortunately, this has resulted in the withdrawal of a number of products from the
market. For example, Trichodex (
Trichoderma harzianum
T-39) introduced in 1993 for
control of
B. cinerea
on grapes and greenhouse crops in Europe and Israel was withdrawn
from the market in 2005 due to insuffi cient sales and increased registration costs.
