Which of the following statements about phytoplasmas is INCORRECT?

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BlackTom AI · Accepted Answer

The topic here is phytoplasmas and their role in plant disease, specifically grapevine yellows. 
Option 1: 'The phytoplasma that causes grapevine yellows is transmitted by insects.' This statement is accurate because many phytoplasmas rely on insect vectors (such as leafhoppers) to move from plant to plant, spreading grapevine yellows. The plant pathogen lifestyle hinges on such vectors, so this is a true claim. 
Option 2: 'Grapevine yellows can only be controlled by uprooting affected vineyards.' This is the statement flagged as incorrect. In reality, disease management for grapevine yellows is multifaceted and includes vector control, sanitation, removal of infected plant material, pruning strategies to reduce spread, replacement with resistant or tolerant varieties where available, and monitoring. Uprooting entire affected vineyards is not the sole or universally required method, making this claim misleading and incorrect. 
Option 3: 'A phytoplasma causing grapevine yellows is causing significant losses in the European wine industry.' This reflects a common agronomic observation: grapevine yellows and related phytoplasmal diseases have caused notable economic impacts in many wine regions, including parts of Europe, due to reduced yield and quality. Therefore, this is a true statement. 
Option 4: 'All phytoplasmas have undesirable effects on plants.' While most phytoplasmas are pathogenic and cause disease symptoms, the phrasing 'all' leaves little room for exceptional cases, such as asymptomatic infections or context-dependent effects. In practice, phytoplasmas are associated with diseases in many plants, but saying they universally have undesirable effects can be overly broad; however, the prevailing scientific view is that phytoplasmas are plant pathogens with negative impacts, so this statement is largely considered true in the typical context. 
Option 5: 'Phytoplasmas are bacteria that can cause disease in plants.' This aligns with the taxonomic and pathogenic characteristics of phytoplasmas: they are Mollicutes (bacteria-like organisms) that cause plant diseases, so this is a correct description. 
Summarizing the reasoning across options, the only statement that misrepresents typical disease management for grapevine yellows is Option 2, which claims uprooting is the only method of control. The rest describe known facts about transmission, impact, and taxonomy of phytoplasmas, albeit with minor caveats in Option 4 about absolutes.

AGRI20044_2025_SM1 Supplementary/Special Exam: Microbiology in Agriculture (AGRI20044_2025_SM1)- Requires Respondus LockDown Browser

Which of the following statements about phytoplasmas is INCORRECT?

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