Agriculture Reference
In-Depth Information
humid years, causing complete crop failure in a matter of days. It often starts as grayish green spots on
older leaves; leaves wither and dry up in dry weather, rot in wet weather. Late blight is rarely a prob-
lem in greenhouse culture, and it is not seed-borne, so seeds may be harvested as long as the fruits
themselves are not diseased.
Various viral diseases can also affect tomatoes. Symptoms: young leaves curling up at the tip, light
streaks along leaf veins. Remove afflicted plants to help prevent viruses from spreading. Curled leaves
may also be caused by physiological factors. New leaf growth in diseased plants often appears normal
at first.
Blossom end rot is not really a disease but rather the result of a calcium deficiency. It occurs in hot,
dry weather followed by rain (or watering). Symptoms: fruits are brown and sunken-in opposite the
stem end. Some varieties ('Black Plum', for example) or individual plants are especially susceptible.
Do not save seed from plants prone to blossom end rot.
CULTIVATION HISTORY
Tomatoes come from the wild currant tomato (
Solanum pimpinellifolium
), a
native of northwestern South America (Ecuador, Peru) which likely spread north in pre-Columbian
times, as a weed. Indian communities in present-day Mexico domesticated it and integrated it into their
irrigated agricultural practices. The cherry tomato (var.
cerasiforme
) is the likely archetype of the wide
array of large-fruited cultivars that Europeans met when they arrived in the New World.
Cross-sections of different tomatoes
After Columbus, the cultivated form of the tomato traveled back to South America and on to
Europe, where it received a mixed reaction upon its arrival. Italians were the first to truly embrace it,
whereas in central Europe it was not even eaten by the peasantry. The tomato was all over Spain and
Portugal by 1600 and was grown in practically every garden and offered in restaurants by the 18th cen-
tury. The Turks brought it to the Balkans (and thence to eastern Europe). Central and western
Europeans held on to the idea that tomatoes were poisonous the longest, though they adopted them
early as an ornamental curiosity. Tomatoes were not commercially available in Switzerland until the
second half of the 19th century. Widespread hunger during World War I turned the tomato into a food
for the people there, while in western Austria and South Tyrol, Italy, tomatoes were not grown widely
until the 1920s.
Although the tomato has been widely grown in Europe for over a century now, the plant still needs
lots of warmth and remains sensitive to cold and wet weather. The wild original forms of tomato are
receiving renewed attention from contemporary plant breeders because of their resistance to diseases
that plague commercial growers. Many new varieties have these resistance traits bred into them. Wild
forms of tomatoes can be grown in the garden in the same way cultivated varieties are grown.
