Powdery mildew of cereals

Signs of the pathogen

A white felt-like coating appears on the stems, leaves, leaf sheaths and sometimes on the ears. Later it becomes powdery and sits on the plant as dense cotton-wool-like cushions.

When to look

• In production crops, assessment is carried out 6–7 days after heading. If the disease appears early, an additional assessment is made at the start of stem elongation.
• From tillering to milk ripeness, disease infection of the crops gradually increased.

How to count

• Infection is rated on the Geshele scale: by the area of leaves and stems actually occupied by mycelium or spots.
• In fields of up to 100 ha, 20 samples of 10 plants are taken (two samples for each 10 ha); on areas of up to 300 ha, two additional samples are taken for each 100 ha. Very large tracts are notionally divided into smaller fields. In each sample, 10 stems in a row are examined and the infection of each leaf (sheath) is determined.

No rate and no spray timing here: both come from the label and the register.

Source of infection

In autumn the disease was found on volunteers and winter wheat plants, above all early-sown crops. This autumn infection is the starting source of primary infection after growth resumes in spring.

Favourable conditions

In warm, wet weather, in dense crops with a high level of nitrogen fertilisation, moderate to severe disease development is likely.

Every fact rests on a quote from its source, and each quote was checked against the page it is printed on.

1. EPPO Global Database · European and Mediterranean Plant Protection Organization
2. Станкевич С. В., Положенець В. М., Немерицька Л. В., Журавська І. А., «Моніторинг хвороб сільськогосподарських культур», навчальний посібник, 301 с. · Інститут біоенергетичних культур і цукрових буряків НААН, Державний біотехнологічний університет; Житомир: Рута, 2022 · p. 156
3. Прогноз фітосанітарного стану агроценозів України та рекомендації щодо захисту рослин у 2025 році · Держпродспоживслужба, НААН, НАН · p. 42, 43
4. Photos: Jie-Hao Ou, iNaturalist, CC BY 4.0 · James Lindsey, Wikimedia Commons, CC BY-SA 3.0 · Clemson University - USDA Cooperative Extension Slide Series, , United States, Wikimedia Commons, CC BY 3.0