tristeza
noun
tris·te·za tri-ˈstā-zə 
: a highly infectious disease of citrus trees grafted on sour orange rootstocks that is caused by a single-stranded RNA virus (species Citrus tristeza virus of the genus Closterovirus, family Closteroviridae) transmitted by aphids and that eventually causes death of the trees
Word History
Etymology
Portuguese, literally, sadness, from Latin tristitia, from tristis sad
First Known Use
circa 1902, in the meaning defined above