CDFA Pest Prevention Plant Regulation Practice Exam

Which type of disease does not typically manifest external symptoms in carriers, as seen in quick decline of citrus?

1. Fungus disease

2. Parasite

3. Virus disease

4. Bacterial disease

The correct answer is: Virus disease

Virus diseases are known for their ability to persist in carriers without showing external symptoms. Unlike other types of plant diseases, such as fungal, bacterial, or parasitic infections, viral infections can often lead to a situation where the host plant appears healthy and shows no visible signs of distress, even though the virus is present and can impact its health and productivity. In the context of citrus quick decline, this disease can spread through vegetative propagation or insect vectors, where the infected plants do not display immediate or obvious symptoms. This can complicate management efforts since the virus can spread unnoticed, allowing for the disease to proliferate before any intervention is taken. This highlights the stealthy nature of viral pathogens, which can undermine the health of crops without overt signs, differentiating them from other plant diseases that often produce visible symptoms in infected hosts.