2019 BARLEY DISEASE SURVEY IN THE SOUTH PEACE REGION OF ALBERTA AND BRITISH COLUMBIA

In 2019, 17 producer fields were surveyed for leaf diseases at the milk to early dough stage of crop development. Growing season temperatures were slightly above normal in May, but cooled off in June and July, while moisture conditions were initially dry in the spring, but were greater than normal in July. Scald and the net-form of net blotch were most common diseases. Severity levels for all diseases were generally low, although moderate levels did occur in a few fields. METHODS: Seventeen commercial barley fields at the late milk to late dough stages were surveyed in the South Peace Region of Alberta (12 fields) and BC (5 fields) from Aug 1 to Aug 20, 2019. Fields were traversed in a diamond-shaped pattern with samples taken at the vertices. Twenty-five leaves (equal numbers of penultimate (flag leaf - 1) and the next lower (flag leaf - 2) leaves) were randomly sampled from a path of 3 to 5 m radius around each vertex. Leaves were collected and placed in envelopes and air-dried for disease assessment later in summer and fall. The percentage of diseased leaf area (DLA) was assessed for scald (Rhynchosporium commune), the net-form of net blotch (Pyrenophora teres f. teres), leaf blotch (Parastagonospora nodorum) and other leaf spots such as spot-form net blotch (P. teres f. maculata) and spot blotch (Cochliobolus sativus). Disease assessments were aided by the use of standard area diagrams. Diseases were identified on the basis of symptoms and sporulation on lesions on leaf pieces which were cut from fresh samples. Leaf pieces were surfaced sterilized (10% bleach/10% alcohol solution for 1-2 minutes), plated on water agar, and incubated at 18 degrees C in light for 3-14 days. Plating was repeated with air-dried leaf pieces where needed. RESULTS AND COMMENTS: Across the region average temperatures were 0.6 degrees C warmer in May, 0.5 degrees C cooler in June and July, and 1.6 degrees C cooler in August than the 20-year normal for the period of 1991 to 2011. Generally, precipitation was at or below normal levels in May and June across the region. In July, there was greater precipitation than normal in Alberta, but lower than normal in BC. Trends shifted in August with less (-3.9 mm) than normal precipitation in Alberta and greater than normal in BC. Results of the disease survey are shown in Table 1. Generally, although most fields had scald and net blotch, average disease severity was low (6.4 and 0.4), respectively. For scald, 24% of fields had a diseased leaf area greater than 10%. Leaf botch was present in 71% of fields with a mean diseased leaf area of 3.1%. Total disease severity was greater in the Alberta Peace region (11.5%) than the BC region (1.11%). Trace amounts of stripe rust were found in two fields and loose smut was found in one field. Both Cladosporium and Alternaria spp. were common on most samples. [GRAPHICS]