Biological control has become an integral part of  plant crop disease management in recent years.

It offers solution to :

1.     Pesticide hazards

2.     Environmental pollution

3.     Pesticide residue in crops and to

4.     Ever increasing cost  of plant protection operations.

Biological control is the process of using one species of organism to control or eliminate another species of organism that is harmful to the crop plants.

Biological control envisages the use of microorganism which are antagonistic to pathogens or any bioagent that restricts the activity of pests or the use of specific genes that are potential suppressors of pathogenic effects of the pathogen or pest.

Biological control of plant pathogens is brought about by reducing the population of pathogens by the bioagents.

It has become the major component of organic farming, restricts the use of chemicals and encourages the exclusive  use of only natural products and beneficial microorganisms in organic farming.

Biocontrol agents belonging to  Fungi, bacteria and virus are known to possess antagonistic effect against plant pathogens.

Mechanisms of action of biocontrol agents:

1.     Hyperaarasitism: Observed with Trichoderma and Rhizactoria solani and Phytophthara maedi

-         Causes hyphal coiling, penetration and hyphal lysis.such hyphal interaction of Trichoderma with pathogens is a commonly observed phenomenon.

2.     Antibiosis :

a.Trichdermin a sequiterpene is an antibiotic compound produced by Trichoderma sp.

b. Acetaldehyde, a volatile antibiotic produced by Trichoderma

c.Dermadine: an unsaturated monobasic acid

3.     Competition:

Trichoderma competes with the pathogen for food and shelter – population of 10⁵ is essential for effective disease control

Bio agents such as VAM  and Trichoderma harzianum used against Phytophthora infection in black pepper roots of cuttings in the nursery.

Microbial consortium
A talc based formulation (IISR Biomix) consisting of a consortium of Plant Growth Promoting Rhizobacteria [Micrococcus luteus (BRB 3)] + [Enterobacter aerogenes (BRB 13)] + [Micrococcus sp. (BRB 23)] is also applied to black pepper in the nursery and main field for enhanced growth and yield.

Biocontrol agents like Pochonia chlamydosporia or Trichoderma harzianum can be applied to control Slow decline (slow wilt)of black pepper.

Cardamom

Pests

1. Cardamom thrips( Sciothrips cardamomi )
2. Borers
a. Shoot/panicle/capsule borer[ Conogethes punctiferalis (Guen . )
b. Early capsule borer ( Jamides alecto )
3. Cardamom whitefly ( Kanakarajiella [Dialeurodes] cardamomi )
4. Root grub ( Basilepta fulvicorne )
5. Hairy caterpillars
6. Shoot fly ( Formosina flavipes )
7. Lacewing bug(Stephanitis typicus)
8. Spotted red spider mites
9. Nematodes
10. Rodents & birds

Diseases

1. 'Katte' (Mosaic) disease: Cardamom Mosaic Virus- vector- all stages of banana aphid Pentalonia nigronervosa, major production constraint encountered by the cardamom industry.

2. Nilgiri necrosis disease:

Biopesticides: Extracts from several plant species were found to adversely affect the breeding potential of aphids. Neem products at 0.1 % concentration
were found to reduce the population of aphids on cardamom and were lethal
to the aphid at higher concentrations. Aqueous extracts of Acorus calamus
(dried rhizome), Annona squamosa (seeds) and Lawsonia inermis (leaves)
were also found to reduce the setting percentage of aphids on cardamom

 3.Kokke kanda- all stages of banana aphid Pentalonia nigronervosa

4. Azhugal or capsule rot: Phytophthora maedi

5.Clump rot or rhizome rot

Chlorotic streak caused by a strain of Banana bract mosaic virus (BBrMV) is an emerging disease of recent origin, which could possibly pose a threat to the cardamom industry in future.

Future thrust should focus on development of resistant
varieties to each of the viruses. Epidemiology, strain variation and emergence
of new viruses need to be looked into. Focus should also be given to the identification and subsequent development of diagnostics for the viruses causing
kokke kandu and Nilgiri necrosis diseases. Development of a certification
system for the production of virus-free planting material and creating awareness on the importance of use of certified material among all stake holders
including farmers, nursery men, extension functionaries and policy makers
are also needed.