Click2Disasters - The Great Hunger - Chapter 4

<body link="0000ff" alink="ff0000" vlink="000000" bgcolor=000033> <table width="100%" bgcolor=000033> <tr> <td align=center valign=top> <table width=90% bgcolor=ffffff> <tr> <td align=center valign=top> <tr> <td> <div align=center><p><b><font face="arial, helvetica" size=5 color=000000><b>THE GREAT HUNGER</p> <p><font size="4">CHAPTER 4 - THE POTATO BLIGHT</b></font></p> </div>  <center> <table width="90%"> <tr> <td align="left" valign="top"> <div align="justify"> <p><font face="arial, helvetica" color="000000" size="3">A devastating plant disease called "Late Potato Blight" <a href="http://www.bakerlab.usda.gov/BakerLab/research6.html" target="_blank"><b>ruins</b></a> potato crops <a href="http://ppathw3.cals.cornell.edu/fry/index.htm" target="_blank"><b>every year</b></a>. Caused by a fungus known as <a href="http://helios.bto.ed.ac.uk/bto/microbes/blight.htm" target="_blank"><b><i>Phytophthora infestans</b></a></i>, the blight destroyed the Irish potato crop of 1845. </p> <p>The disease first infects exposed <a target="_blank" href="http://www.apsnet.org/education/LessonsPlantPath/Lateblit/Images/LATEB_02.HTM"><b>leaves</b></a> and stems of the potato plant. As the <a href="http://megasun.bch.umontreal.ca/People/lang/species/phyti/phytimap.html" target="_blank"><b>fungus</b></a> grows (the link takes you to a drawing of its genetic map), it produces <a target="_blank" href="http://www.apsnet.org/education/LessonsPlantPath/Lateblit/text/discycl2.htm"><b>spores</b></a>. When those spores are washed into the soil by rain or irrigation water, the fungus spreads. Once the fungus gets into the soil, it infects the <a target="_blank" href="http://www.apsnet.org/online/feature/lateblit/chapter1/1-13.jpg"><b>tubers</b></a> and causes them to rot. </p> <p>Certain weather conditions help the disease. A prolonged rainy period, for example, will help the fungus grow and spread. Ireland had such a weather pattern during the summer <a target="_blank" href="http://www.apsnet.org/online/feature/lateblit/chapter1/top.htm"><b>of 1845</b></a>.</p> <p>Once the fungus takes hold of <a target="_blank" href="http://www.apsnet.org/online/feature/lateblit/chapter1/plant.htm"><b>the plant</b></a>, it can <a target="_blank" href="http://www.apsnet.org/online/feature/lateblit/chapter1/1-10.jpg"><b>spread</b></a> quickly. First it acts like a parasite, getting its food supply from the plant. Then it increases so rapidly the fungus becomes a <a target="_blank" href="http://www.apsnet.org/online/feature/lateblit/chapter1/1-18.jpg"><b>pathogen</b></a>, causing disease and <a target="_blank" href="http://www.apsnet.org/education/LessonsPlantPath/Lateblit/Images/LATEB_04.HTM"><b>massive</b></a> losses. </p> <p>The fungus itself is not very visible. It <a target="_blank" href="http://www.apsnet.org/education/LessonsPlantPath/Lateblit/Images/LATEB_03.HTM"><b>looks like</b></a> a kind of white mildew on the surface of infected potato leaves and stems. The disease progresses, however, and as the tubers become <a target="_blank" href="http://www.apsnet.org/education/LessonsPlantPath/Lateblit/Images/LATEB_05.HTM"><b>infected</b></a> they begin to rot. Unchecked, the disease spreads until it runs out of food. By then, the whole potato crop can be destroyed, as it was in 1845 Ireland. </p> </div> <p align="center"><font size="2"><a href="great_hunger_ch3.htm">GO TO LAST CHAPTER</a>     <a href="great_hunger_ch1.htm">BACK TO FIRST CHAPTER  </a>   <a href="great_hunger_ch5.htm">GO TO NEXT CHAPTER</a></p><br> </td> </tr> </table>  </td> </tr> </table>  </td> </tr> </table> </body>