By Scott Hartley PAg, Crop Protection Lab manager
Sample submissions to the Crop Protection Lab have greatly increased. Eighty samples were submitted in July, for a total of 127 submissions for 2019 so far. Root rot complex in pulse, cereal and oilseed crops was the main issue in most of the samples diagnosed. Although the lab does not conduct PCR testing specificity in root rots, the typical reddish-brown and disfigured root systems were observed. Plating and microcopy confirmed a Fusarium species in many cases. Oospores were observed in several of the samples. Oospores are indicative of Aphanomyces or Pythium species. Rhizoctonia was also identified in a few samples.
Problems in chickpea crops was noted in southern Saskatchewan in July. Ascochyta blight was diagnosed in samples sent to the Crop Protection Lab and also observed in the field. Plant tissue was plated and root rot was present, but did not appear to be highly significant in the samples.
Climatic conditions – specifically significant precipitation and higher temperatures – have been ideal for the onset of Ascochyta and other diseases in crops for much of the province since about mid-June.
Several herbicide carryover and application problems also contributed to the number of samples received. Nutrient deficiencies and environmental stress also added to submissions from both field crops and trees.
Dutch elm disease (DED) submissions have reached 331 this year, with 96 diagnosed as positive. Confirming DED requires scraping and plating of samples and an incubation period of about 10 to 12 days.