smaller than that needed for application via
drench applications. Because the protectant
is localized near the germinating seed,
it can provide a protective shield around
the plant when it is most susceptible to
damping-off. The degree of protection,
however, needs to be evaluated further
because a considerable variation in sensitivity
to phosphonates has been observed
with different isolates of Phytophthora
spp. (8,18). Seed treatment also reduces
the risk of developing resistance in the
pathogen against phosphonates because the
amounts of chemical used are too small to
exert selective pressure on the pathogen or
only a small fragment of the pathogen
population is exposed to the active ingredient.
Large applications of pesticide to soil
and foliage had resulted in loss of efficacy
to Fosetyl-Al within some isolates of the
lettuce downy mildew pathogen, Bremia
lactucae Regel (5). Seed treatment also
will preclude enhanced degradation of
phosphonates by soil microorganisms because
there will be less exposure to the
chemical.