2012 - Washington Red Raspberry Commission

esearch directly addresses a #1 priority of the Washington Red Raspberry commission, soil
fumigant techniques and alternatives.
Justification and Background:
Root lesion nematodes, Pratylenchus penetrans, are migratory endoparasites, migrating between
the soil and roots. This nematode is prominent in western Washington soils and has been shown
to reduce raspberry vigor and yield (Gigot et al., accepted; Zasada and Walters, unpublished
data). Currently, P. penetrans is managed in red raspberry by pre-plant fumigation with Telone
C-35; there are few reliable post-plant nematicides registered for use in raspberry. We previously
evaluated 13 post-plant nematicides for ability to suppress P. penetrans in raspberry (Zasada et
al., 2010). Of the tested products only Vydate (oxamyl) and fosthiazate suppressed this nematode
on raspberry plants. It is unlikely that fosthiazate will be labeled for us on red raspberry.
However, Vydate was recently labeled for us on non-bearing raspberry for the control of
nematodes in Washington (EPA SLN NO. WA-120005). This is a different type of use compared
to that in Canada where Vydate is labeled for use on bearing plants; therefore it is essential that
we identify the optimal way to apply Vydate
Figure 1. Population densities of Pratylenchus penetrans
to maximize nematode control.
in plots treated with Vydate in spring 2012.
In 2012, we conducted on-farm trials with
the goal of evaluating the phytotoxicity of
Vydate to raspberry. Vydate was applied to
either newly planted tissue cultured or
dormant cane plants twice in May or June.
Phytotoxicity was evaluated and soil samples
were collected before treatment and soil and
root samples collected in the fall for
quantification of P. penetrans populations.
Initially, there were very few nematodes
detected in these fields with average
populations of 0, 3, and 1 P. penetrans/100 g
soil in Fields 1, 2, and 3, respectively. In the
fall P. penetrans population densities in roots
were significantly higher (indicated by * in
Figure 1) in nontreated plots compared to
Vydate-treated plots. The same trend was
observed in Field 3, however it was not
statistically significant. Vydate was not
phytotoxic to raspberry in these trials.
Pratylenchus penetrans population density
800
600
400
200
0
800
600
400
200
0
800
600
Field 1
Field 2
Field 3
*
*
*
Soil (#/100 g soil)
Root (#/g root)
These results are significant because they
demonstrate that Vydate will be a very
important nematode management tool for
Washington raspberry growers. Currently the
only application timing recommendation for
Vydate is that soil temperature be at least 45
°F at a depth of 8 inches. The Vydate
400
200
0
Nontreated May 2x June 2x
Vydate Treatment
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