Agriculture Reference
In-Depth Information
Vertebrate enemies
Birds, bats, squirrels, rats, monkeys, pigs and other animals, including
elephants, can become a real problem in orchards. These animals cause
damage to the tree trunk and eat the fruit. Birds can devastate a whole crop,
with several methods having been tried and discussed in Chapter 3.
For rodents, metallic plates around the trunks can be used to prevent them
from climbing to the tops or to prevent damage to the bark of the base of the
tree. Poisoned baits or parai n blocks containing an attractant and a poison
that are fairly weatherproof are also a good solution. The use of repellents or
trunk protectors can sometimes be useful.
Other less important miscellaneous problems include algae, mosses and
parasite plants. Algae can be controlled with copper.
Integrated pest management (IPM)
This approach involves the use of many of the above procedures and
practices in combination to obtain the best control with the least
environmental impact. A careful analysis of the crop and pests' development
cycles need to be established to develop a strategy to combat the problem
at its most susceptible phase. Computer systems can assist by analysing
the environmental conditions and predicting the development of certain
problems. IPM potentially can save money, protect the environment and
allow the orchardist to market a product with fewer pesticide residues. For
tropical fruit the market demands products that are of the highest quality,
and without blemishes or insect and disease damage, making it dii cult to
avoid the use of some chemicals (Penman
et al.
, 2003).
GIRDLING AND SCORING
Girdling consists of taking of a ring of bark, 4 mm to 3 cm wide, from the
main trunk (Fig. 4.7a), scaf old branches or smaller branches to stop the
movement of sugars in the phloem, especially from the canopy to the roots.
This procedure is usually done with two knives or blades that are joined or
welded together to cut through the bark and phloem, which are removed once
the cuts have gone around the whole stem. Sometimes spiral girdling is used,
and semi-girdles of two Cs in opposite positions but at dif erent heights of the
branch are used to avoid a complete blocking of the fl ow.
Scoring is a mini-girdle by which the bark of the trunk or branch is cut in
a circumscribing form with a saw blade or a knife. This wound is very narrow
and will take about 3 weeks to heal, while a normal girdle will take about
3-4 months. Scoring is made by orchardists to manage fruit tree size and to
improve yield. However, scoring has variable ef ects on vegetative growth,
