Which of the following is NOT a common soilborne or root pest affecting potted plants?

• A. Root-knot nematodes
• B. Fusarium crown and root rot
• C. Phytophthora root rot
• D. Spider mites

Answer: (D)

Soilborne and root pests are organisms that live in the potting mix and attack the plant’s below-ground tissues. Root-knot nematodes, Fusarium crown and root rot, and Phytophthora root rot all fit this group because they inhabit soil and invade roots or the crown, impairing water and nutrient uptake. Spider mites, in contrast, are above-ground pests that feed on the surface of leaves, causing stippling and sometimes webbing, not attacking roots or living in the soil. That’s why spider mites are the option that is not a common soilborne or root pest. Managing them follows different routes—improving humidity and washing leaves, using miticides or insecticidal soaps—whereas soilborne problems are addressed through sterile potting mixes, good drainage, and soil-targeted treatments.