PCC MarchApril Final Draft

Figure 3. Left, pycnidia protruding through bark cracks; right, arthrospores of Neoscytalidium dimidiatum causing limb dieback of fig.
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masses of black spores. These are not true spores but are
small segments of mycelia that become black as the tissues
dry up and break down into small pieces, producing a layer
of black powder under the bark. The fungus also produces
pycnidia that protrude through small cracks of the bark (See
Figure 3). However, it is the spores produced in masses by
the breaking mycelia called arthrospores. that can be spread
readily by air and/or splashing rain and can cause infections
of pruning wounds and other injuries of branches.
Survey of Affected Areas
Before doing pathogenicity studies with the Neoscytalidium
fungus, we wanted to make sure that this fungus was found
frequently throughout the area where fig trees showed similar
symptoms to the ones we initially observed in Madera
County. Therefore, a survey of 16 fig orchards with branch
dieback symptoms, representing all the major fig varieties
(Black Mission, Calimyrna, Conadria and the male trees
(Roeding and Stanford caprifig varieties)) was done in Fresno,
Madera and Kern counties. Neoscytalidium was isolated in
all of these orchards.
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26 Progressive Crop Consultant March / April 2021