Question

Circular patches of drying and lodging of matured rice plants with immature stages of causal agent is seen in a field infested with:

• A. Hopper
• B. Gundy bug
• C. Red spider mites
• D. Dirty root nematode

Hint:

The terms "circular patches of drying" and "hopper burn" in rice fields are the primary indicators for the Brown Planthopper (BPH).
This pest always congregates and feeds at the base of the tillers.

Answer 1

The Correct Option is A

In rice cultivation, different insect pests feed on different parts of the plant and produce highly specific field symptoms.
Sucking pests that feed on the sap of the plant stem can disrupt the vascular system, causing rapid dehydration, drying, and structural collapse of the crop.

Step 2: Detailed Explanation:
The Brown Planthopper (BPH, Nilaparvata lugens) and the White-backed Planthopper (WBPH, Sogatella furcifera) are among the most destructive insect pests of rice.
Both the nymphs (immature stages) and adults congregate in large numbers at the base of the rice plants, just above the standing water level.
They use their piercing-sucking mouthparts to penetrate the phloem vessels and feed on the plant sap.
This feeding blocks the transport of water and essential nutrients to the upper parts of the plant.
As the pest population multiplies rapidly, the intense feeding pressure causes the rice plants to turn yellow, dry up, turn brown, and lodge (fall over).
Because planthoppers spread radially from a primary focus of infestation, the damage is typically visible in the field as distinct, circular patches of dry, lodged straw-colored crop.
This characteristic symptom is known as "hopper burn."
Let us compare this with the other options:
- Gundhi Bug (Leptocorisa acuta) feeds on the milky sap of developing rice grains, causing incomplete grain filling and chaffy, empty panicles, but does not cause circular lodging of stems.
- Red Spider Mites feed on leaves, producing tiny chlorotic spots, yellowing, and webbing on the foliage, rather than sudden basal lodging of mature crops.
- Dirty Root Nematodes attack the root system, leading to overall stunting, chlorosis, and root decay, but do not produce sudden circular patches of lodged mature tillers.

Step 3: Final Answer:
The combination of "circular patches of drying and lodging" with the presence of immature stages (nymphs) is a clear diagnostic symptom of a hopper (specifically, Brown Planthopper) infestation.