Grape
growers in Europe begin to experience difficulties in production in 1840's.
An English gardner, Mr. Tucker, observed that the young leaves of his master's
grapes were covered with a white powder. This was similar to a disease on
peaches he had seen once before, it was called powdery mildew.
He was careful and made comparisons with what he found on peach trees. He
determined that a chemical could control this problem. He mixed together powdered
lime and sulfur and spread this on the grape leaves. That autumn he had lots
of plump grapes while others were devasted by powdery mildew. In fact by 1854,
the French wine production had been reduced by about 80%, but addition of
sulfur applications brought the industry back. Since the grape was vital to
the French economy, thousands of foreign grapevines were imported in for developement
of resistant cultivars. With these imported root stock came a second problem.
This problem was first called etise of the vines, but later was called 
Phylloxera
or "dry" leaf disease. It was noticed in the early 1860's and caused
a yellowing or reddening of the leaves in spring and early summer and then
a falling of the withered leaves in July or August. The fruit production was
decreased and the next year the vine would die. The disease moved slowly but
with devastating purpose. M. J. Plachon, a French plant pathologist, determined
the cause to be a tiny aphidlike insect of the genusPhylloxera
that largely lived underground on the grape roots. This pest was not an
important problem in America, because the American grape rootstock had coevolved
with the insect. So Phylloxera-resistant rootstock from America was
planted and then French grape shoots were grafted onto these rootstocks. This
way the French could get the desired fruit production while using the Phylloxera-resistant
roots.
Of
course this is not the end of the story, of course there is more............Every
good story has a part three right............Well, this story does have a
part three. In 1875, a disease called downy mildew of 
grapes
was thought to occur only in United States. But somehow the pathogen made
its way to France, probably on one of the thousands of grapevines America
had sent to France for grafting. In 1878, it appeared in France and over the
next five years it invaded almost every vineyard in Europe. The spread was
facilitated by the excessive wet summer which prevailed in Europe during the
1870's and 1880's. Lucky for the people (or so they thought) everyone was
used to fungi, so many educated and experienced men observed and experimented.
But no one could solve the problem. 
The
fungus, Plasmopora viticola, causes irregular small yellow turning
to brown spots on the upper surface of the leaf and a white downy growth on
the under side of the leaf. The wine production lost nearly $50 billion. But
the good news.....the chemical pesticide era began. Alexis Millardet, a French
botany professor, noticed while walking some grapes covered with a bluish-white
wash, these grapes had healthy leaves while neighboring plants had downy mildew.
When he questioned the farmer of the vineyard, he discovered the farmer had
sprayed the grapes along the road with a mixture of lime and copper sulfate
to discourage pilferers. Millardet then began experimenting with different
combinations of lime, iron, and copper salts but eventually determined the
best combination was the original formula. He called it Bordeaux mixture.
This mixture was and still is highly effective against most bacteria and fungi.
