2018 Growing Season Clinic Sample Diagnosis

Planting for the 2019 small grains crop is set to begin. In anticipation of the next season here is an overview of what small grain problems that were diagnosed by the WSU Plant Pest Diagnostic Clinic between November 2017 and August 2018.

Root based issues are the most common problem sent in for diagnosis due to the ambiguous symptoms which can include yellowing, thinning, and reduced vigor. Plants suspected to be infected by viruses such as Soilborne Wheat Mosaic Virus, Wheat Streak Mosaic, and High Plains Virus are also frequently sent in for testing. Please note that negative results from these tests are not reflected in the table below. Abiotic issues that are frequently seen are weather-related, Physiological Leaf Spot, aluminum toxicity, and chemical damage such as potential herbicide damage which can only be confirmed by the use of a certified analytical lab as well as ‘burning’ from fertilizers.

Rotation legume crops frequently had root rot pathogens (Pythium, Fusarium, Rhizoctonia and Aphanomyces) and the recovery of Metalaxyl-resistant Pythium from both soil and plant tissue (http://smallgrains.wsu.edu/metalaxyl-resistant-pythium/). Due to this season’s prolonged wet, cool weather Ascochyta leaf spot complexes were recovered frequently from both chickpea and peas.

Plant samples can be sent in to the WSU Plant Pest Diagnostic Clinic year round. Soil tests are also available for select fungal pathogens. For more information on submitting a sample and specialized testing available please visit the Plant Path Diagnostics page.

Table: Small grain samples submitted to the WSU Plant Pest Diagnostic Clinic and the diagnosis associated. Abiotic issues are disorders such as nutrient issues, weather damage, soil characteristics, and variety traits. A diagnosis of abiotic stress is concluded based on the lack of evidence of pathogens or pests, information provided by the submitter, and symptomology of known abiotic issues.

Grain Type

Diagnosis

Soft White Winter Wheat Rhizoctonia Root Rot
Triticale Snow mold (Typhula species)
Soft White Winter Wheat Soilborne Wheat Mosaic Virus
Hard Red Spring Wheat Cold Weather Damage
Soft White Winter Wheat Eyespot and Stripe Rust
Hard Red Spring Wheat Rhizoctonia Root Rot

Suspected Root Lesion Nematode (Pratylenchus)

Hard Red Winter Wheat Abiotic Stress (chemical (not herbicide))
Information not provided Fusarium Head Blight
Barley Abiotic Stress (soil-based issues)
Information not provided Physiological Leaf Spot
Hard Red Spring Wheat Wireworm
Hard Red Spring Wheat Seed failure
Spring Feed Barley Root Rot complex (Rhizoctonia, Pythium, and Fusarium)
Spring Feed Barley Rhizoctonia Root Rot
Information not provided Cereal Leaf Beetle parasitoid larva not observed
Soft White Spring Wheat Root Rot complex (Rhizoctonia, Pythium, and Fusarium)
Barley Suspect Scald
Soft White Winter Wheat Abiotic Stress (Cold damage or chemical)
Soft White Winter Wheat Abiotic Stress (Gravitropism after lodging events)
Information not provided Wheat Streak Mosaic Virus
Malting Barley Grain (x9) Sooty head mold fungi
Wheat with bending at the joints. The odd angles on the stem are a result of the plant attempting to grow upright after multiple lodging events.
Wheat leaves dashed with Soilborne Wheat Mosaic Virus discoloration.
Wheat leaves showing a mosaic of ‘dashed’ or rectangular areas of discoloration typical for Soilborne Wheat Mosaic Virus.
Discoloration on leaves due to weather and fertilizers applied.
Discoloration and necrosis of leaves as a result of a combination of weather and chemicals (fertilizers) applied.
Yellowing caused by Soilborne Wheat Mosaic Virus.
Yellowing and mosaic of wheat infected by Wheat Soilborne Mosaic Virus.

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