In a physical vineyard there must also be weed and pest control. Such things as the Glassy-winged sharpshooter, leafhoppers, and mealybugs are just some of the pests a vineyard must endure. Weeds such as filaree, mustard, annual brome grass, fescue and other such vegetation can cause problems in a vineyard. The sun itself can cause problems for the vintner.