Cultural Practices in Pest Management-2

4.      Tillage practices

·         Effect of tillage

-          The type of cultivation can markedly influence the soil environment and affect insect survival either indirectly by creating unfavourable conditions and by exposing the insects to their natural enemies or directly by physical damage caused during the actual tillage process.

-          Thus with tillage, pests are killed mechanical injury, starvation through destruction of debris, desiccation and exposure.

-          Another most common use of tillage is to control the weeds.

- Fall ploughing results in the exposure of the insects to the environment unfavourable or even detrimental to them. The insects also sustain mechanical injury. Ploughing also removes the weeds that might have been used by the insects for feeding or breeding. To make it effective, the ploughing must be done at the proper time, for example, the white grubs are exposed to birds that kill them, on an early ploughing The grubs escape he late ploughing as they move down deep in the soil.

 

·         Examples of tillage effects

-          A disc-plough treatment caused up to 73.5% mortality of the overwintering larvae of Dectes texanus, a pest of sunflower, compared with 39.7% mortality using a sweep plough.

-          The wheat stem sawfly in North Dakota has been reduced as much as 75% by cultivation-caused injury, exposure, and starvation.

 

·         Limitations

-          Tillage has several limitations.

-          Serious side effects of tillage include loss of organic matter, accelerated loss of soil to wind and water erosion, soil compaction etc.

 

5.      Habitat diversification/Cropping systems/Intercropping

 

·         Increasing crop diversity as opposed to monoculture can sometimes be used to increase predator and parasite populations in a given crop or to repel away insect pests from susceptible crops to nonsusceptible crops.

·         This can be achieved by following the improved polyculture practice that includes various types of intercroppings instead of monoculture.

·         The diversified cropping system generally reduces the pest abundance although there is also evidence of increased abundance of some pests in some cases.

·         Because wrong intermixes can increase pest problems on one or more of the intermixed crops, the advantages of the practice must be carefully weighed against potential harmful effects.

 

6.      Plant Density

In general an increase in plant density i.e. a reduction in plant spacing, seems to reduce pest numbers.

·         Causes of the effects

-          One of the main reasons for the response of insect to varying plant density has been the contrast between plants and their soil background and the effect of this on the optomotor landing response of the flying insects.

-          Other reasons that have been given to explain lower number of insect in dense plantings have included host plant condition, the presence of excess vegetation acting as a deterrent, changes in the microenvironment favoured by the pest and its natural enemies and the crop’s attractiveness.

 

 

7.      Trap crops/Trap logs

 

TRAP CROPS

-          The practice of attracting pest to small plantings of crops which are then destroyed or sprayed with toxicant has been quite successful against some plant nematodes parasitic weeds and insect pests.

-          Examples:

-          In Hawaii, squash and melon fields are often surrounded by a few rows of corn which attract large numbers of melon flies, major pests of melons and squash.

-          Treatment of the trap plants generally controls the flies, leaves no insecticide residues on the melon or squash crop and is harmless to natural enemies of the crop plants.

 

TRAP LOGS

A somewhat similar approach, using logs as traps, has been effective against Englemann spruce beetles in the Rocky mountain region. Because the beetles are more strongly attracted to recently cut logs than to living trees, the logs have been used to attract beetles which are then destroyed.

 

Limitation

 

-          A major limitation of using trap crop technique is the expense of producing and destroying a crop that brings no income.

 

 

8.      Water management

 

·         Water management procedures (e.g. timing of irrigation, loading, drainage) based on a sound understanding of pest biology may provide economical and effective control of some pests.

·         Drainage of irrigated pastures, regulation of water levels in rice paddies and avoidance of stagnant water buildup in habitats are particularly important mosquito management practices.

·         Careful control of irrigation water is one of the most effective ways for controlling soil pathogens.

·         Flooding of fields has been used to control some root infecting fungi.

·         Management of irrigation water can also reduce certain weed problems.

 

9.      Fertilization

It is a general belief that healthy plants and well fertilized plants are less infested with pests and they are capable of repelling pr repairing the damage by pest without reflection on yield

 

10.  Miscellaneous practices

Prunning, training, use of pest free planting materials etc. 

( ...end)

Bismark Bangali

BSC  in Agrotechnology 

 

 

 

Khulna University.