Crown rot pathogens are associated with higher losses for wheat crop farmers, but information about the distribution and
prevalence of these pathogens in Chile is inadequate. Distribution and prevalence of wheat (
Triticum aestivum
L.) crown
rot pathogens were examined in a survey of 48 commercial fields from December 2011 to February 2012 in southern Chile.
These fields were located between Collipulli (37º56’00” S; 72°26’39” W) and Purranque (40º50’30” S; 73°22’03” W).
Severity of crown rot disease was determined through visual assessment of the first internode of 20 tillers obtained from
each field. Incidence of crown rot pathogens per field was determined by plating the 20 tillers on Petri plates with 20%
potato dextrose agar amended with lactic acid (aPDA) medium. Resulting fungal colonies from monoxenic culture were
identified by morphological or molecular-assisted identification. Severity of crown rot varied between 11.3% and 80% for
individual fields. Culture plate analysis showed 72.2% of stems were infected with some fungus.
Fusarium avenaceum
,
F.
graminearum
, and
F. culmorum
, pathogens associated with Fusarium crown rot disease were isolated from 13.5% of tillers.
Gaeumannomyces graminis
, causal agent of take-all disease in cereals, was isolated from 11.1% of culms.
Phaeosphaeria
sp., an endophyte and possibly a non-pathogenic fungus, was isolated from 13.9% of tillers. Pathogenic fungi such as
Rhizoctonia
spp. and
Microdochium nivale
, other saprophyte, and several unidentified non-sporulating fungi were isolated
at frequencies lower than 3% of the total. Fusarium crown rot and take-all were the most prevalent and distributed crown
rot diseases present in wheat crops in southern Chile.
