Grey mould

Symptoms

• It mainly infects young seedlings or fruiting plants. At first, spots of wet rot with a grey fluffy coating appear, and the coating later turns brown.
• On the leaves, the leaf blade or only part of it dries up and curls.
• Brown spots with an abundant grey coating appear on the stems.
• Infected heads fall out in pieces. They differ from heads infected with Sclerotinia rot by the grey coating and small sclerotia.

Signs of the pathogen

Flat, dark brown sclerotia of the pathogen appear at the infected sites.

When to look

• It can appear as early as on seedlings, especially on volunteers, and on mature plants during flowering.
• On sunflower, the disease is seen at the head ripening stage.
• Towards the end of ripening, the disease can be found on the heads, often together with Sclerotinia rot.
• On peas, the disease appears on the pods at the end of the growing season.
• The first sunflower disease assessment is made after emergence and before thinning. Count plants that died from white and grey rot, plants infected with rust, and healthy plants.
• At the third assessment, at flowering, grey rot is recorded among other diseases.
• Before harvest, the crops are surveyed, in particular for grey rot.

How to count

• Determine the percentage of seedlings killed by rots and infected with rust. Examine 50 consecutive plants at each of 10 points along the diagonal or along two parallel lines, 5 m in from the field edge.
• It is recommended to assess the intensity of rot infection on heads, especially white and grey rot, on a five-point scale. 0 points: heads not infected; 1 point: small spots on the upper side of the heads covering up to 25 % of the surface.

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

Favourable conditions

• In the post-harvest period, excessive rainfall favours the increase and spread of the disease.
• The disease always develops during the wetter period.
• The disease spreads during sunflower ripening when rainfall is heavy, primarily in oblasts where it has already developed significantly.
• The rot appears and develops in winter and spring oilseed rape crops at humidity of 60–90%, air temperature of +17..+27 °C and when a source of infection is present.
• On peas, the disease is favoured by relative air humidity above 70% and an average daily temperature of +18..+20°C during pod ripening.

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. 170, 175, 177, 178
3. Прогноз фітосанітарного стану агроценозів України та рекомендації щодо захисту рослин у 2025 році · Держпродспоживслужба, НААН, НАН · p. 77, 110, 111, 132
4. Photos: Rasbak, Wikimedia Commons, CC BY-SA 3.0 · Jerry Cooper, iNaturalist, CC BY 4.0