Agriculture Reference
In-Depth Information
In 1879, A. T. Hatch of Suisun planted some 2,000 seedlings to graft,
but ran out of budding material for the last 200. Several of these
ungrafted seedlings performed particularly well together, including
one he named Nonpareil, which became California's most popular and
valuable almond variety. By happy chance, three other good varieties
flowered concurrently with the Nonpareil, providing all the necessary
pollen. California almond growers are still completely dependent on bees
to pollinate their crops. They rent hundreds of thousands of beehives
from Arizona every winter to ensure they have enough. Almond growers
continue to support research on bee behavior through their commodity
board, and might be more attuned to ecological relationships in their
farming systems than other growers.
Of all the insects active in almond orchards, only five species cause
economic damage. The two chief pests today are both lepidopteran. The
peach twig borer (
Anarisia lineatella
) is native to Europe, where
it attacked stone fruit and almonds. Carried to California in the 1880s,
it was the major almond pest until the 1940s, when the navel orange
worm (
Amyolois transitella
) arrived. The lifecycle of the navel orange
worm (commonly abbreviated to NOW) meshes tightly with almond
development. In almonds, the NOW found a remarkable ecological com-
panion that offers it food and shelter. Nourished by water and
agrochemicals, almond orchards proliferated throughout the Central
Valley after 1960, but these brought biological changes that made them
more hospitable to the insect. In the late 1970s, NOW crop damage
reached a crisis which provoked growers to reconsider their chemical
pest-management strategies.
Some controversy surrounds the navel orange worm's precise evolu-
tionary locus of origin. The UC IPM manual for almonds describes it
as a native of the southwestern United States and Mexico, but Fred
Legner and others believe that it originated further south in the
Neotropics, perhaps in Argentina. Navel orange worms mature into
gray-and-black moths about 12 millimeters long. During the cool spring
weather, adults live 2 or 3 weeks. During hot summers, they survive less
than a week. Adult females mate within two days of emergence from
their larval stage and begin to lay an average of 85 eggs each. These eggs
are less than 0.25 millimeter across. They hatch in from 4 to 23 days.
The larvae then forage for several days or weeks before emerging as
