Gabriele Stoll
Natural Crop Protection in the Tropics
Letting Information Come to Life
Methods of Field Protection
Insects
Intercropping
Considerable evidence has emerged over the
past twenty years to suggest that pest populations and problems
are much greater in crops grown in monoculture than in those
grown in polyculture (i.e. with intercropping). Increasing the
diversity of plant species is one practical measure for
reducing the impact of pests.
Plant diversity can be increased by:
• intercropping, the growing of more
than one crop in the field
• trap cropping, the planting of
plants that are more attractive to certain pests than the
target crop, and
• plant attractants, plants that
offer feed or shelter to beneficial insects.
Intercropping in vegetables
Aphids
(Aphidae)
Cabbage butterfly
(Pieris brassicae)
Diamondback moth
(Plutella xylostella)
Fruit borer
(Helicoverpa armiqera)
Fruit and shoot borer
(Leucinodes orbonalis)
Loopers
general
Aphids (general)
Thrips (Thrips
tabaci)
Whitefly (Bemisia
tabaci)
Whitefly (Bemisia
tabaci)
Tomatoes
Lettuce, Brussels sprouts,chilli, cabbage
Chilli
Cabbage
Cabbage
Tomato
Eggplant
Crucifer
Onion
Chilli
Tomato
Onion
Basil: Optical effects, repellent
Eggplants are an effective trap crop for
those aphids migrating early and transmitting virus diseases
such as CVMV.
Non-green foliage plants as well as
strong-odoured plants such as onion, leek,
garlic, shallot, mint, coriander, fennel, bitter gourd. This
principle gives very good control effects.
Tomato, coriander, garlic: act as
repellents
Marigold (Tagetes erecta) as trap crop.
Synchronization of flowering of tomatoes
and marigold is crucial. 25 day old tomatoes and 40 day old
marigold seedlings resulted in simultaneous flowering. Planting
marigold every 10, 12, 14 and 16th row resulted in an
infestation of only 6.0, 7.1, 10.3 and 10.4%.
Peucedanum graveolens: acts as repellent
Radish: according to the ayurvedic
concept,
seeds and main vein of radish are of
antiseptic value.
Onion: repellent. According to the
ayurvedic concept, onions have a killing effect on bacteria and
insect larvae.
Coriander: acts as attractant for
beneficial insects, thus promoting biological control.
Onion
Cucumber planted in alternating rows 30
days before tomato delays infection of the tomato by the
whitefly-vectored tomato yellow leaf curl virus.
The printed version contains more
information about:
Intercropping in cotton
Intercropping in potatoes
Intercropping for varios crops
Intercropping of rice with fish
Protecting newly planted seeds