Question

A common biocontrol agent of plant disease caused by fungi is ______.
A. Agrobacterium
B. Glomus
C. Trichoderma
D. Baculovirus

Answer 1

Hint:-Biocontrol agents are the microbes which are employed to control some harmful organisms like pathogens and pests. These include bio-herbicides that control weeds, control of Cacti by cochineal insects, production of transgenic crop plants like tomato, tobacco, etc.

Complete Answer:-
Agrobacterium is a gram-negative bacteria that induces tumors in plants. It is now commonly used as an important tool for the transfer of desirable genes in the plant DNA.
The diseases caused by fungi spread from plant to plant in the form of spores. The fungal pathogens produce either localized or generalized symptoms like necrosis or tissue death, stunting, etc. on their hosts. To control fungal diseases, various measures are taken. The important measures are use of resistant varieties, destruction of infected plant parts and crop residues.
Trichoderma is a fungus present in the soil that acts as a biological agent for the control of plant diseases. It is the best biocontrol agent for controlling fungal diseases in plants.
Baculoviruses are the pathogenic DNA viruses which infect and kill many insect pests and other arthropod pests. Most important baculovirus involved in biological control is the Nucleopolyhedrovirus. These viruses are species specific and have narrow spectrum insecticidal effects so do not have any negative effects on the other organisms. These control pests like potato beetles, aphids, and corn borers.
Thus, the right option is C.

Note:- Plant diseases may be defined as an abnormal growth or development caused by either an abiotic or biotic factor of the environment. Most plant diseases are, however, caused by various biotic environmental factors called pathogens like bacteria, protozoa, fungi and nematodes.