It allows somewhat better equipment passage through the vineyard during wet conditions for application of fungicides. When rains occur fungicides are needed and it is very difficult to drive a tractor with sprayer through mud. In a few instances sod middles could help reduce excessive vine vigor. With the presence of Pierce's disease in central Texas, there is a question as to whether grasses host the grape strain of the bacteria. Sod middles can compete with the vines for water and nutrients.
Uncontrolled weeds can harbor insect pests.
Weeds can be especially harmful to young vines during the establishment years. When weeds or sod grow beyond there bounds extreme weed control systems such as weed eater or lawn mowers create problems with trunk injury. This is especially true when tall weeds are allowed to overwinter, die and become tough. Overwintering weeds under the vines is a major problem in Texas and it makes cultivation or chemical weed control in the spring very difficult or impossible. The best weed control system for a new vineyard is to kill all the weeds before planting.