Question

write a report about ( disease caused by Ascomycota powder mildews )..

Answer 1

The majority of known fungi belong to the Phylum Ascomycota, which is characterized by the formation of an ascus (plural, asci), a sac-like structure that contains haploid ascospores. Many ascomycetes are of commercial importance. Some play a beneficial role, such as the yeasts used in baking, brewing, and wine fermentation, plus truffles and morels, which are held as gourmet delicacies. Aspergillus oryzae is used in the fermentation of rice to produce sake. Other ascomycetes parasitize plants and animals, including humans. For example, fungal pneumonia poses a significant threat to AIDS patients who have a compromised immune system. Ascomycetes not only infest and destroy crops directly; they also produce poisonous secondary metabolites that make crops unfit for consumption. Filamentous ascomycetes produce hyphae divided by perforated septa, allowing streaming of cytoplasm from one cell to the other. Conidia and asci, which are used respectively for asexual and sexual reproductions, are usually separated from the vegetative hyphae by blocked (non-perforated) septa.

Powder mildew

Powdery mildew fungi (Ascomycota phylum) are obligate biotrophic plant pathogens that can only grow and reproduce on living host cells. They infect a wide range of plants, including many crops and the diseases they cause are common, easily recognizable and widespread.

The functional investigations in these genetically intractable organisms have been hampered by their obligate biotrophic nature recent advances in genomics and transcriptomics have contributed tremendously to understanding of powdery mildew biology. Comparative genomics was a powerful tool to pinpoint what distinguishes powdery mildew fungi from other filamentous plant pathogens and helped to better understand how obligate biotrophy evolved. Comparative genome analyses among isolates in both the wheat and the barley powdery mildew lineages revealed isolate-specific mosaic genome structures of evolutionary young and old haplogroups. In addition to providing hints into the evolutionary origin of powdery mildew fungi the observed mosaic genome structure also reflects the reproductive mode of these pathogens and explains how the large standing genetic variation is generated in powdery mildew populations.

Powdery mildew diseases are caused by many different species of fungi in the order Erysiphales, with Podosphaera xanthii ( Sphaerotheca fuliginea) being the most commonly reported cause.The causes of this disease by spores overwinter in plant debris and begin producing more spores in the spring. These spores are carried to your plants via wind, insects, and splashing water.Periods of dampness or high humidity: Powdery mildew is less common during prolonged rainy seasons and in extreme heat.Low soil moisture combined with high humidity levels at the plant surface favors this disease.

The symptoms of disease by first sign of problems is usually white powdery spots or patches on the top side of leaves or on plant stems. The powdery surface growth gradually spreads to cover the entire leaf including the undersides until the plant looks like it's dusted with white powder. Infected leaves turn yellow and twisted.

powdery mildew can be wiped off the leaves for a quick visual check. Infected leaves should be discarded. Lower buds are the most susceptible. Powdery mildew is difficult to 100% eradicate control requires prevention, early detection and pro-active measures.

Treatment

• Plant resistant cultivars in sunny locations whenever possible.
• Prune or stake plants to improve air circulation. Make sure to disinfect your pruning tools (one part bleach to 4 parts water) after each cut.
• Remove diseased foliage from the plant and clean up fallen debris on the ground.
• Use a thick layer of mulch or organic compost to cover the soil after you have raked and cleaned it well. Mulch will prevent the disease spores from splashing back up onto the leaves.
• Milk sprays, made with 40% milk and 60% water, are an effective home remedy for use on a wide range of plants. For best results, spray plant leaves as a preventative measure every 10-14 days.
• Wash foliage occasionally to disrupt the daily spore-releasing cycle. Neem oil and PM Wash, used on a 7 day schedule, will prevent fungal attack on plants grown indoors.
• Water in the morning, so plants have a chance to dry during the day. Drip irrigation and soaker hoses will help keep the foliage dry.
• Use a slow-release, organic fertilizer on crops and avoid excess nitrogen. Soft, leafy, new growth is most susceptible.

The life cycle of powdery mildew includes both sexual and asexual reproduction. Asexual spores produce conidia and the sexual stage produces cleistothecia (ascocarps or fruiting bodies) which contain ascospores.