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Oomycota, Also Known As Water Molds Or Downy Mildews

by Kristina Kaye Maglabe

Oomycota are commonly known as water molds or downy mildews. They can be quite destructive as they absorb their food from what is in their surroundings. They also attack an organism and feed from there. This is the reason why oomycetes are very important in decaying and recycling. They are also sometimes used in making composts. Fish and plantations experience destruction due to these organisms.

They can be describes as having a filamentous growth. This is the reason why it was classified as a fungus in the past. The difference is that oomycetes do not have chitin, a mix of glycan and cellulosic compounds, like fungi. Another difference is that fungi are not haploid, but a diploid.

These are also parasites to other organisms. On water, these can be found on fish scales, eggs or on amphibians. The effect of each oomycota differs in each environment. If the water is stagnant, the fish will develop lesions. Some salmon have this problem when they go upstream to spawn. Other water dwellers like arthropods, nematods, diatoms and rotifers as well as other invertebrate can also be affected by these parasites.

On land, plants have these parasites as well. The worst case scenario is that people can ingest these from the plants. It affects the vegetation by causing rotting roots, blister rusts, white rusts, downy mildews and seedling dampening mold. Broccoli, onion, potatoes, peas, beans, grapes and other plants, crops and vegetation have become victims to oomycota infestation.

Trees as well as shrubs are no match for these critters. Another reason why it was first thought of as fungi is because of the rusts that it causes to these greens. In the family Peronosporaceae, Plasmopara, Peronospora, Pseudoperonospora, Sclerospora, and Bremia are the ones that are responsible for downy mildew in most plants. Other obligate and non – obligate parasites are also the ones to blame for root rot, rusts and blights.

In history, two species of oomycota have devastated humanity. The late blight of potato disease caused thousands of people starving. Potatoes originated from North America but became instantly stable in Europe. Due to the cold and damp weather in Europe, the spread of these parasites became rapid. In 1846, Ireland has lost its entire stock nationally due to oomycetes. It caused starvation because it was the staple food for the poor in those times. This is the Great Famine.

In 1870, the downy mildew of grapes almost cost us the whole French wine industry. It came from America and was brought by accident when the winery owners wanted to cross breed it to their vines that were affected by aphids. The day was saved due to the discovery of Bordeaux. The infestation became under control. Fungicide was also first discovered.

Oomycota have been an aid to new discovery in science and in winery industry. But it will always be known as the species that devastated and starved millions of people. These organisms can be microscopic or just tiny in size, but remember, David defeated Goliath.