Thursday, 5 February 2015

Biological or organic approaches for Pest and Disease Management

In organic agriculture the pests and diseases can be managed by a cultural
practices and biological approaches. These practices are region and crop
specific.  

Cultural practices    

The cultural methods are the traditional practices followed by farmers for
modulating crop growth through adjustments in time of sowing, cultural
practices and plant population density for altering the microclimate to minimize
the risks.
 

Pest & Pathogen Control Comparison Chart

a) Crop rotation 
Rotating the crop belonging to one family with one of a different family helps
to solve the pest to a large extent. Rotating groundnut with maize will reduce
the attack of white grubs. Rotating pigeon pea or chickpea with other nonleguminous
crop is a good practice for managing fusarium wilt and nematode
problems.
     

 b) Trap crops
 

A trap crop is a crop that is planted to lure insect pests away from the cash
crop. The trap crop can be a different plant species, a different variety, or just
a different growth stage of the same species, as long as it is more attractive to
the pests when they are present. Successful use of trap crops is challenging.
The trap crop must be more attractive to the pest than the cash crop, and
steps must be taken to ensure that the pests in the trap crop don’t later
migrate to the cash crop. The pests in the trap crop can be eliminated by crop
destruction
 

Mustard is a trap crop along with cabbage for the control of diamond back
moth, aphid and leaf webber. African marigold is a good trap crop for the
American boll worm, besides it also attracts the adults of leaf miner for egg
laying on the leaves. Maize plants can be a trap crop to attract fruit fly adults
in vegetable cultivation wherein fruitfly is a major problem and also for cotton
bollworm


c) Intercropping
 

Intercropping generally has positive effects in terms of reducing the
occurrence of insect pests. Insects find difficult to locate host plants as the
visual and chemical stimuli for the host are not so strong and aromatic odour
of other plants can disrupt host finding behaviour. Intercropping also interferes
with the population development and survival of insect pests. For example,
cabbage along with carrot or tomato is an important intercrop combination to
effectively manage diamond back moth. Sowing cowpea as intercrop with
groundnut minimizes leaf miner infestation. Green gram intercropped with
sugarcane reduces the incidence of sugarcane early shoot borer. Growing
short-duration pulses like black gram, cowpea, soybean and green gram as
intercrops in cotton increase the effectiveness of natural enemies like
coccinellids, syrphids, trichogrammatids etc. In Bhutan some of the common
intercropping systems are
             

              Maize+ ginger/turmeric
              Maize +soyabean
              Maize+ Potato
 

d) Use of resistant /tolerant varieties
 

Genotypes showing tolerance and resistance to insect pests and diseases are
to be used for sowing. Plants have their sophisticated mechanism to protect
them from the attack by pests. Certain genotypes act as detterents,
antifeedants and some encourage the predators of pests. There should be
constant watch to update such genotypes in the region. A series of resistant
varieties are available for all the crops in accordance to the agro-climatic
zone.

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