![]() infestans produce dark green, then brown then black spots on the surface of potato leaves and stems, often near the tips or edges, where water or dew collects. Both sporangia and zoospores are short-lived, in contrast to oospores which can persist in a viable form for many years. infestans on water films found on leaves or soils. The zoospores released from sporangia are biflagellated and chemotactic, allowing further movement of P. Sporangia are spread by wind or water and enable the movement of P. The different types of spores play major roles in the dissemination and survival of P. Hormonal communication triggers the formation of the sexual spores, called oospores. There is also a sexual cycle, which occurs when isolates of opposite mating type (A1 and A2, see § Mating types below) meet. germ tube emergence from the sporangium), and the re-establishment of hyphal growth. The asexual life cycle of Phytophthora infestans is characterized by alternating phases of hyphal growth, sporulation, sporangia germination (either through zoospore release or direct germination, i.e. Life cycle, signs and symptoms Infected potato Life cycle on potato The name Phytophthora infestans was coined in 1876 by the German mycologist Heinrich Anton de Bary (1831–1888). The species name infestans is the present participle of the Latin verb infestare, meaning : "attacking, destroying", from which we get the word "to infest". The genus name Phytophthora comes from the Greek φυτό–( phyto), meaning : "plant" – plus the Greek φθορά ( phthora), meaning : "decay, ruin, perish". Lesion growth rates are typically optimal at a slightly warmer temperature range of 20 to 24 ☌ (68 to 75 ☏). The pathogen is favored by moist, cool environments: sporulation is optimal at 12–18 ☌ (54–64 ☏) in water-saturated or nearly saturated environments, and zoospore production is favored at temperatures below 15 ☌ (59 ☏). The organism can also infect some other members of the Solanaceae. Late blight was a major culprit in the 1840s European, the 1845–1852 Irish, and the 1846 Highland potato famines. Early blight, caused by Alternaria solani, is also often called "potato blight". "So our farmers are always looking for new ways to manage and control late blight on their farms.Phytophthora infestans is an oomycete or water mold, a fungus-like microorganism that causes the serious potato and tomato disease known as late blight or potato blight. It's a heavy metal and it accumulates in the soil, and so there are issues around continued and ongoing use of that product. It's a devastating disease for the potato crop, and it can destroy a crop both in the field and in storage. And that is copper, or copper sulfate," said Karen Murchison, research co-ordinator for the P.E.I. Certified Organic Producers Co-op. "Organic producers, in particular, only have one product that they can use to effectively control late blight on tomato or potato crops. organic producers who are excited about the potential selenium has as a natural way to ward off late blight. Organic growers excitedįofana has been working with P.E.I. While the lab tests have been successful, Fofana said he can't try selenium in an actual field setting because the tests could release late blight spores into the environment. I was astonished with stopping the growth and sporulation of the pathogens," he said. In the 1840s, late blight was to blame for major European crop failures and the Irish Potato Famine, which caused widespread hunger and drove an estimated 2 million people to leave their homeland for North America and other destinations.įofana tested the selenium on two other plant pathogens in vitro, with equal success. Late blight, pictured here, can ruin entire tomato crops and cause damage to potatoes. "We noticed that there was a very low incidence of the disease in those that were treated with different concentrations of selenium," Fofana said. "I asked repeat that three times again, because I want to make sure before we… publish that." Fofana was so surprised by the results that he ran the tests more than once. The researchers did their tests in the greenhouse, and in vitro in the lab. ![]() But they soon concluded treating only the leaves of the growing plant would be enough. They then wanted to see what impact it could have in preventing disease, starting with late blight.įirst, they soaked potato seeds with a selenium solution before planting them, and sprayed the leaves with it. The researchers added selenium to flax, soybean and potato plants, and noticed positive results. "Our interest was how to increase antioxidant capacity of crops." 'Very surprised' "Working on late blight came, I would say, by accident," said Fofana, a geneticist with Agriculture and Agri-Food Canada. The researchers did their tests in the greenhouse and in the lab. ![]()
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