Epidemiological features of monocyclic plant diseases:

• Perennial trees and plantations often suffer from root rots, vascular wilts, and cankers that act monocyclically: (A) is true.
• By definition (Vanderplank), monocyclic diseases complete only one infection cycle per growing season without repeating secondary cycles within the same season: (B) is true.
• Because primary inoculum resides in soil (resting spores, sclerotia), reducing initial inoculum ($x_0$) through solarization, fumigation, or fungicide soil treatment effectively controls disease: (C) is true.
• Due to limited long-distance airborne dispersal, soilborne monocyclic diseases remain localized and endemic in specific fields or geographic pockets: (D) is true.

Epidemiology of wheat stem rust race Ug99:

• Ug99 (lineage TTKSK) was first detected in Uganda in 1998 (and formally identified/named in 1999 by Pretorius et al. after testing). It overcame the widely deployed Sr31 resistance gene: Statement (C) is accurate.
• Over the past two decades, numerous subvariants within the Ug99 lineage (e.g., TTKST defeating Sr24, TTTSK defeating Sr36) have evolved and spread across East Africa and the Middle East: Statement (D) is accurate.
• Ug99 did not originate in Uttar Pradesh; it has not become established in India.

Ploidy levels of major commercial crops:

• Tomato (Solanum lycopersicum): Diploid ($2n = 2x = 24$): (C).
• Commercial dessert banana (Musa acuminata / Cavendish group): Triploid ($2n = 3x = 33$): (D).
• Upland cotton (Gossypium hirsutum): Allotetraploid ($2n = 4x = 52$): (B).
• Bread wheat (Triticum aestivum): Allohexaploid ($2n = 6x = 42$): (A).
  Ascending order of ploidy: $2x$ (Tomato) $\rightarrow$ $3x$ (Banana) $\rightarrow$ $4x$ (Cotton) $\rightarrow$ $6x$ (Wheat).