Leafroll

Leafroll is a plant symptom characterized by the downward curling or rolling of leaves, sometimes accompanied by yellowing (chlorosis), reddening or purpling of tissues, and distorted growth. It can occur in many plant species and may result from viral infections, nutrient or mineral deficiencies, drought or heat stress, root damage, or pest feeding. In crops, leafroll can limit photosynthesis and overall vigor, potentially reducing yield or affecting quality.

In viticulture, grapevine leafroll disease (GLRD) is a widespread condition caused by several grapevine leafroll-associated viruses (GLRaV-1, GLRaV-2, GLRaV-3, GLRaV-4, and others). Transmission is primarily through sap-sucking insects such as mealybugs and scale insects, with spread also facilitated by infected planting material. Symptoms in grapevines include persistent downward rolling of leaves on affected shoots and interveinal chlorosis or coloration changes, which can vary by cultivar and climate. The disease can diminish vigor, bud fruitfulness, and yield, and may alter fruit composition.

Diagnosis combines field observation with laboratory tests to confirm GLRaV infections, using methods such as ELISA or RT-PCR. Management focuses on preventing virus introduction and spread: using certified virus-free planting stock, removing infected vines (roguing), and controlling vector populations through integrated pest management. Quarantine measures and clean-stock programs help protect vineyards from new infections.

Leafroll-like symptoms may also arise in other crops from nutritional deficiencies, drought, or different pathogens, but the term is most often associated with the grapevine leafroll complex in viticulture.