Question: What causes the white frothy substance on the stems of my grapevines?
Answer: An insect known as the spittlebug causes the white frothy foam substance on stems of several types of plants.
Recently, many people with muscadine grapevines have been noticing white foam on the vines and grapes that looks like someone has been spitting on them. Seeing this white frothy mass of foam causes alarm and concern for many people because it appears so unusual.
Many gardeners often mistake this white foam as a disease or are concerned that it is oozing from the plant itself. In this situation the culprit is an insect known as the spittlebug. The spittlebug is often found on many different plants including grapevines, pecan trees, shrubs, turf grass, and weeds. Unfortunately, it is not a means of weed control. This white “spit” is not the insect itself but is produced by the spittlebug. If you removed some of the foam, you would see some small insects attached to the plant. The spittlebug creates this foam like substance by secreting a fluid that when combined with air begins to bubble, which gives it a spit or foam appearance. The spittlebug produces the substance to protect itself from other insects. It also helps to keep them warm while developing into an adult spittlebug.
On a positive note, although seeing this mass of white foam causes concern for your plants health, the spittlebug is not known for causing any injury. Therefore, eliminates the necessity to apply pesticides.
If you find the appearance of the foam to be unsightly, just hose down the plant to wash it away or wait for the next good rain shower to take care of it. Whether you call the unsightly appearance on your plants foam or spit, rest assured that the spittlebug will not harm the plants and no treatment is necessary or recommended.
Reminder: A growing program this year is the “Sampson County Friends of Horticulture”. This program offers monthly “How To” Horticultural Seminars. Please call (910) 592-7161 for more information. Please call the Sampson County Cooperative Extension Center at (910) 592-7161 with your horticultural questions and to register for any upcoming events. Be sure to check out the Ask An Expert Widget at sampson.ces.ncsu.edu for any questions you may have.