Plant diagnostic laboratories that test for Pierce's disease in grapevines can also detect X. fastidiosa in infected oleander. A soil or tissue test can help determine if the symptoms are caused by an excess of minerals. If salt toxicity is the problem, plants will improve if salts are leached through the soil and below the root zone, whereas no improvement will be seen in plants infected with leaf scorch bacteria. This insect acquires the bacteria from infected plants while feeding on the xylem sap. The bacteria replicate in the sharpshooter's mouth, so that once a sharpshooter adult acquires the bacteria, it is infectious for life.
Nymphs lose the bacteria when they molt.
When the sharpshooter moves to another plant to feed, it takes bacteria with it in its mouthparts and deposits them into the next host plant. When the bacteria enter the xylem, they can then multiply and spread throughout the plant to such an extent that the xylem vessels are blocked and water can no longer be transported to that part of the plant. The insect is dark brown on top and has a slightly lighter underside. The top of the arrowhead-shaped head is stippled with ivory or yellow dots. These spots may rub off when the insect comes in contact with the foliage and therefore are not always present.