19. Which of the following is the best strategy to control wheat rust? O A. Invasive insect species to attack rust
B. Fungicides to treat affected crops and planting rust-resistant varieties
C. Citrus greening to prevent the spread of rust
O D. Insulation using green roofs to limit rust

B. Fungicides to treat affected crops and planting rust-resistant varieties

Explanation:

Leaf rust is a disease caused by the fungus Puccinia triticina which affects leaves, stems and grains in wheat and related cereals (i.e., barley and rye). This disease is known to affect crops in moist conditions. Leaf rust disease is spread through fungi spores from infected wheat plants to healthy plants. Recently, leaf rust-resistant varieties have been developed by crop improvement programs aimed at introducing leaf rust-resistant (lr) genes involved in resistance against this important crop disease. Moreover, there are different types of fungicides (e.g., Prothioconazole and Tebuconazole) used for chemical control of this disease.