Sometimes, the most severe destruction can come from the smallest things. Pests, such as the potato blight and Colorado beetle, seem to be relatively tiny, can create huge problems for the stability of a country and the health of humans.
Potato blight has the scientific name of Phytophthora infestans. It attacks potato at the pores and drains all of the nutrients out of the potato, makes the potato’s outer flesh dry, grainy, red- brown rot and invades towards the center of the potato. Potatoes with diseases were often thrown away entirely. At first, when European researchers looked at the disease, they thought it must have come from Peru, the land of potato. However, later on, the ancestral home of the disease was found to be Mexico, where the center of diversity located, as the P. infestans seemed to be more diverse than anywhere else in the world. But when Alexander von Humbolt visited Mexico in 1803 to examine the potato, he found out that the potatoes in Mexico were imported from the Andes, where the blight was even more diverse than in Mexico.
The blight was spread first in the United States, then to European across the Atlantic. It was believed to travel to Europe from Peru aboard a guano ship to Belgium. Potato arrived in Belgium right at the time that the country was in need of a new foreign crop which was stronger to defeat European plant pathogens. As a result, potato later was widely spread in Europe. Between 1532 and 1840 there weren’t many ships traveling straight from Peru to Europe because of the ban from Spain and domestic political chaos. The voyages from Peru to England brought guano and it was believed that one of these ships brought potato blight to Belgium. The first symptoms like bruise, dark spots started to appear in West Landers in 1844, made it the launchpad for Europe’s first widespread epidemic of potato blight. The flow of wind brought the spores spread far from its original place. The oomycete hopscotched to farms around Paris by August. In a short period of time, it arrived in Netherlands, Germany, Denmark, England and Ireland. The whole continent was contaminated.
The worst infected region was Ireland. The extremely vulnerable agricultural conditions in Ireland made it especially easy for the disease to spread and bloom. The small number of potatoes in Ireland helped the blight to spread easier. Another reason was due to the uniformity of the crops that half of the country was covered with a single species: the Lumper. Irish farmers had long been farming and plowing fields with the wacho system. They cut out blocks of sod, flipped them upside down and piled them into long, broad ridges separated by deep furrows- the lazy-bed farmings. Layers of sod constructed nutritious good soil that farmers could plant crops densely. The unplowed ridges also helped the roots to grow deep into the soil, which prevented erosion and preserved the nutrients after each harvesting seasons. Unfortunately, not knowing about these advantages, agricultural reformers in Ireland claimed that they need to abandon this way of farming and replace with deep, throughout plowing to release soil nutrients and to plant as much as possible. To use plowing machines, they had to get rid of the lazy-beds. Reformers believed that furrows were a waste of land. Less and less wachos were spotted in Europe. Reformers had no idea that by getting rid of the lazy-beds, they encouraged the blight to grow and spread. The ridges of the wachos made it impossible for the blights to grow because it couldn’t survive warm temperature and dry soil. Since water was drained into the furrows, it washed away and beneath the growing tubers, carrying zoospores away from them. Also, with this kind of farming, plants needed less nutrients and fertilizers to grow. Eliminating lazy-beds also meant eliminating all of these incredible advantages, which helped the potato blight to spread and caused excruciating fail to Europe.
Another quarantine in the United States was caused by Leptinotarsa decemlineata called the “Colorado beetle”. It was originated in south-central Mexico, eating on buffalo bur. Then the Spaniards carried cows and horses to the Americas. Native Indians helped bring the buffalo bur tangled in horse manes, cow tails and native saddlebags north. The beetles followed and traveled along side as well. Bison, which migrated from south to north in the spring, also took part in spreading the beetles further into the United States. Farmers tried to get rid of these pests with all kinds of chemicals. At first, it was working but gradually the pest became evolved and immune to the pesticide so farmers had to keep on finding new chemicals to get the blight under control. By 1819, in the Middle West, it was first spotted in a ten-acre garden in northeastern Kansas which belonged to a farmer named Thomas Murphy. There were so many beetles in his field that he could barely see the leaves through the swarm of tiny glittering bodies. Murphy’s farm wasn’t the only one that got invaded by beetles. It spread north and east, expanding its range by fifty to a hundred miles year, arrived in Illinois and Wisconsin in 1864, Michigan by 1870. Seven years later it was found in regions from Maine to North Carolina. Infected potatoes from the US came to England by shiping holds. It came to France and then moved east from Athens to Stockholm. In Americas, the disease was found all the way from south-central Mexico to north-central Canada.