Question

the first bio-herbicide developed in 1981 was based on-
A.Phytophthora palmivora
B.Phytophthora infestans
C.Bacillus thuringiensis
D.Azadirachta indica

Answer 1

Hint:Herbicide is a chemical used in agriculture to inhibit or completely halt the growth of unwanted extra plants growing in fields along with the main crop.

Complete answer:Herbs or weeds are fast-growing plants which are causing a developing problem for all farmers across the world. These plants hog all the nutrition, water, sunlight, nutrients, etc. from the surroundings and make the actual crop compete for all these essential things. This diminishes the growth of the crop and affects overall growth as all the necessary material required for growth is used up by these fast-growing weeds.
Many types of herbicide products is available in the market. Among all those, bio-herbicide is the most efficient and environmentally friendly. When we use any biological agents like fungus, algae, bacteria, etc. to keep control of the growth of weed or to get rid of it, it is known as a bio-herbicide. The secondary metabolite products or phytotoxic compounds derived from these organisms also serve as herbicidal agents.
Out of all the mentioned options, Phytophthora palmivora is one of the herbicides used to get rid of milkweed which used to cause a lot of decrease in the yield of citrus fruits. Myco-herbicides are one of the class of bio-herbicides which uses fungus which is parasitic to plants. This herbicide is reliable, easy to apply, easy to store, and safe for the farmers and the crops too. The fungal herbicides are cost effective too, as they produce a huge number of spores once applied, there is no need to apply them after every crop cycle. These herbicides are even effective after years of application and thus protect crop by being eco-friendly at the same time.
Thus the correct answer is option A. Phytophthora palmivora.

Additional information:
The commercial name of myco-herbicide available in the market in 1981, which was obtained from Phytophthora palmivora was ‘Devine’. It was used against Morrenia odorata commonly known as milk weed vine or strangler vine and showed effect after 2 years of application.

Note: Out of all the options mentioned above, Phytophthora infestans is a fungus affecting Potato and Tomato crops called potato blight. Bacillus thuringiensis is a bacteria that naturally produce compounds that are toxic to pests especially affecting crops like cotton. It is used to produce varieties of cotton which are naturally resistant to the pest bollworm. Azadirachta indica is the name of Neem which is generally used as bio-pesticide for various agricultural products.