Powdery mildew

Powdery mildew is a fungal disease that affects a wide range of plants. Powdery mildew diseases are caused by many different species of fungi in the order Erysiphales. It is one of the easier diseases to spot, as its symptoms are quite distinctive. Infected plants display white powder-like spots on the leaves and stems. The lower leaves are the most affected, but the mildew can appear on any part of the plant that shows above the ground. As the disease progresses, the spots get larger and thicker as massive numbers of spores form, and the mildew spreads up and down the length of the plant.

Powdery mildews of various plants

Powdery mildew of grape

"Erysiphe necator" (or "Uncinula necator") causes powdery mildew of grapes. It produces common odors such as 1-octen-3-one and (Z)-1,5-octadien-3-one [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12009998&dopt=Citation] .

Powdery mildew of wheat and barley

"Blumeria graminis", the fungus that causes powdery mildew of grasses, can persist between seasons in wheat stubble that is left in the field, or in wheat that is left to overwinter. It thrives in cool humid conditions. Controlling the disease involves eliminating those conditions as much as possible. Wheat plants should not be overcrowded in the field. This allows better air circulation among the lower parts of the plants, which lowers the humidity levels. Nitrogen fertilizers encourage lots of leafy growth, and in farming systems that use them they should be used sparingly to control powdery mildew. Crop rotation with non-host plants is another way to keep mildew infection to a minimum. Reducing splash from contaminated soil also helps control spores. Chemical control is possible with anti-fungals such as triademefon and propiconazole. Some farmers are experimenting with spraying plants with waste milk, with varying degrees of success.

Powdery mildew of onions

The fungus causing powdery mildew of onions is "Leveillula taurica" (also known by its anamorph name, "Oidiopsis taurica"). It also attacks the artichoke.

Cure For Powdery Mildew

Left untreated, powdery mildew will kill your plant. Common fungicides bought at a local garden store will help by either killing the fungus or by not allowing the fungus to make spores and reproduce. When applying, be sure to spray the leaf, the underside of the leaf, the stem connecting the leaf to the vine, and the vine itself. These fungicides, though, are not cheap and there are some natural ways to treat the powdery mildew. Baking Soda is a very versatile, readily available, and relatively inexpensive; it also can help control and even cure Powdery Mildew. A mixture of one tablespoon Baking Soda, 2.5 tablespoons vegetable oil, and 4-5 drops of liquid soap added to a gallon of water will act as a fine, natural, and inexpensive fungicide (be sure to agitate spray bottle regularly while applying to keep the ingredients from separating). Another natural cure for this mildew is a mixture of one part milk (any kind or brand) to three parts water.

Reproduction of Powdery Mildew

Powdery Mildew reproduces through what is known as cleistothesium. This structure is circular in shape and is a totally enclosed ascocarp. This is a dense, hard, fungal mass created from fungal tissues. The ascocarp cracks open and releases bodies called asci (singular Ascus). These asci hold the ascospores the 'seed' of the fungus.

ee also

*Erysiphales
*Oidium (genus)
*Powdery mildew (barley)

External links

* [http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&id=52586 About "Erysiphe necator"]
* [http://www.naturalwaylawn.com/disease/pm.html Powdery Mildew and Lawn Care]
* [http://www.safecrop.org/english/output/proceedings.html SAFECROP - Proceedings of the 5th International Workshop on Grapevine Downy and Powdery Mildew]