Powdery mildew of lilac, or ''Erysiphe syringae'' (formerly ''Microsphaera syringae'') is a fungal pathogen of

lilac ''Syringa'' is a genus of 12 currently recognized species of flowering woody plants in the olive family or Oleaceae called lilacs. These lilacs are native to woodland and scrub from southeastern Europe to eastern Asia, and widely and commonly ...

Importance

The host of the fungal pathogen, ''

Syringa vulgaris ''Syringa vulgaris'', the lilac or common lilac, is a species of flowering plant in the olive family, Oleaceae. Native to the Balkan Peninsula, it is widely cultivated for its scented flowers in Europe (particularly the north and west) and Nor ...

'' or the common lilac, is an ancient plant with significance in horticultural activities and wild roots in eastern Europe. Its Latin epithet, vulgaris, translates into ‘common’ in English, and was popularized by the pioneer taxonomist

Carl von Linné Carl Linnaeus (23 May 1707 – 10 January 1778), also known after ennoblement in 1761 as Carl von Linné, Blunt (2004), p. 171. was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming organi ...

. One of the first dutiful observations of the pathogen, ''E. syringae'', was made in a journal of the German Botanical Society, Berichte der Deutschen Botanische Gesellschaft, where it was observed as a powdery mildew pathogen unique to lilacs referencing the physical characteristics of its

ascocarp An ascocarp, or ascoma (: ascomata), is the fruiting body ( sporocarp) of an ascomycete phylum fungus. It consists of very tightly interwoven hyphae and millions of embedded asci, each of which typically contains four to eight ascospores. Ascoc ...

appendages. The pathogen contributes to a deathly and diseased look. Common lilac is known for its spring flowers, which can be altered due to decay of flowering stems after intense infection.

Symptoms

Powdery mildew of lilac leaves an opaque-white discoloration on the leaves of ''S. vulgaris''. This process is predominant at the end of the season but can begin to take place during new growth. Eventually the fungal pathogen contributes to the damaging and early senescing of the infected leaves. The opaque-white discoloration is mycelial growth along the surface of the leaf. When the pathogen is sufficiently advanced, the presence of small dark dots indicates the production of

cleistothecium An ascocarp, or ascoma (: ascomata), is the fruiting body (sporocarp (fungi), sporocarp) of an ascomycete phylum fungus. It consists of very tightly interwoven hyphae and millions of embedded ascus, asci, each of which typically contains four to ...

( chasmothecium), an important structure in the protection of potential inoculum.

Treatment

There are methods to treat powdery mildew using home-made preparations including fresh milk, which contains the active anti-pathogenic compound

lecithin Lecithin ( ; from the Ancient Greek "yolk") is a generic term to designate any group of yellow-brownish fatty substances occurring in animal and plant tissues which are amphiphilic – they attract both water and fatty substances (and so ar ...

. Lecithin is recognized by the European Union as a treatment for powdery mildews diseases and is commonly available in the soy-derived formulation ‘soy lecithin’. Other experimental treatments include using baking soda (disrupts pH), neem oil (fungicidal properties), or sulfur containing solutions. Historically,

flowers of sulfur Flowers of sulfur (British spelling flowers of sulphur) is a very fine, bright yellow sulfur powder (substance), powder that is produced by sublimation (phase transition)#Purification by sublimation, sublimation and deposition (phase transition), ...

has been prepared into a dust and applied to the leaves. Synthetic compounds such as

thiophanate-methyl Thiophanate-methyl is an organic compound with the formula C6H4(NHC(S)NH(CO)OCH3)2. The compound is a colorless or white solid, although commercial samples are generally tan-colored. It is prepared from ''o''-phenylenediamine. It is a widely use ...

propiconazole Propiconazole is a triazole fungicide, also known as a DMI, or demethylation inhibiting fungicide due to its binding with and inhibiting the Lanosterol 14 alpha-demethylase, 14-alpha demethylase enzyme from demethylating a precursor to ergosterol. ...

and

chlorothalonil Chlorothalonil (2,4,5,6-tetrachloroisophthalonitrile) is an organic compound mainly used as a broad spectrum, nonsystemic fungicide, with other uses as a wood protectant, pesticide, acaricide, and to control Mold (fungus), mold, mildew, bacteria ...

are used to treat variety of powdery mildew diseases, as well as other fungal pathogens. Many chemical treatments are known to contribute to

disease resistance Disease resistance is the ability to prevent or reduce the presence of diseases in otherwise susceptible hosts. It can arise from genetic or environmental factors, such as incomplete penetrance. Disease tolerance is different as it is the abilit ...

, and can be harmful if not used with appropriate caution. Compounds with high risk such as

can be referred to in the FRAC (Fungicide Resistance Action Committee
Code List document
To avoid health risks refer to the product's label and the appropriate

Material Safety Data Sheet A safety data sheet (SDS), material safety data sheet (MSDS), or product safety data sheet (PSDS) is a document that lists information relating to occupational safety and health for the use of various substances and products. SDSs are a wide ...

. Cultural controls such as selective pruning can prevent suitable environmental conditions of the pathogen by increasing air circulation. Collection and destruction of plant debris can disrupt the pathogen’s life cycle.

References

{{taxonbar, from=Q10488583 syringae Fungal plant pathogens and diseases Fungus species