Fall, 1992 (v5n1)
by Chuck Ingels
Can organic apples be grown profitably in California? Based on
two years of SAREP-funded research, the answer appears to be related
to two issues: climate, and the development of more effective
codling moth control. If organic apples are grown where the climate
is favorable for codling moth or apple scab development and more
effective methods of codling moth control are not developed, the
organic crop is not profitable. If the orchard is located where
there is little codling moth or apple scab, the crop is profitable.
The research, conducted in three apple districts, was led by
Sean Swezey, entomologist with the Agroecology Program
at UC Santa Cruz, Janet Caprile, Contra Costa farm advisor,
and Paul Vossen, Sonoma County farm advisor. At each site,
organic apple production was compared to conventional production
in replicated experiments for two years.
Controlling codling moth ("the worm in the apple") proved
to be the overriding obstacle to profitable organic apple production
in Sonoma and Contra Costa Counties. The arsenal of materials
used to battle this pest included numerous sprays of Codling Moth
Granulosis Virus (CMGV), ryania, Bacillus thuringiensis (Bt),
Bt plus oil, and oil alone. Still, codling moth damage in Contra
Costa County amounted to 30 percent in 1990 and 40 percent in
1991. In Sonoma County, 18 percent and 34 percent of the fruit
(average of three varieties) were infested in 1990 and 1991, respectively;
in 1991, 56 percent of the Red Delicious apples were damaged.
In Watsonville (Santa Cruz County), however, there were no significant
differences in damage between the conventional and organic systems.
Damage in the conventional plots of all sites was quite low.
The cool coastal climate of this region offers a distinct advantage,
which usually allows only two flights of codling moth compared
to three or even four flights in other regions.
Yields and net returns in Sonoma and Contra Costa Counties were
inversely correlated to damage by codling moth. Average yields
of the organic apples in Sonoma County were 30 and 64 percent
lower than conventional apples in 1990 and 1991, respectively.
Production was also affected by untimely rains, which caused
apple scab damage. Costs exceeded income for organic apples.
In Contra Costa County, yields in the organic treatments were
about 20 percent lower than the conventional for 1990 and 1991;
packable fruit was reduced by 53 and 80 percent, respectively.
The organic system had an increasingly negative net return each
year, while the conventional system had increasingly positive
net returns. In Santa Cruz County, yields were significantly
higher in the organic system in two of the three years studied,
with correspondingly higher returns per acre.
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