Which one of the following is not caused by Phytoplasma

Correct option is D

Phytoplasma diseases are caused by wall-less prokaryotic organisms that affect plant vascular tissues. Sandal spike, grassy shoot of sugarcane, and little leaf of brinjal are well-known phytoplasma diseases. Black rot of crucifers is caused by a bacterial pathogen and not by phytoplasma.
Information booster: Phytoplasmas are transmitted mainly by insect vectors such as leafhoppers. They cause symptoms like witches’ broom, yellowing, stunting, and proliferation of shoots. These pathogens are restricted to the phloem tissues of plants. Management focuses on vector control and removal of infected plants.
Why other options are incorrect: (a) Sandal spike is a classic example of phytoplasma disease. (b) Grassy shoot disease of sugarcane is caused by phytoplasma infection. (c) Little leaf of brinjal is also caused by phytoplasma.