Today is the one of the days when you find many things in the vineyard!  Mealybugs (white one in the middle of the picture) are also observed, mainly at the base of the shoot (or a spur in this case).  You also see a scale insect on this picture.  Please note that both mealybugs and scale insects can transmit several virus pathogens, including the ones cause grapevine leafroll disease.   Unfortunately, once the vine is infected, only remedy is removal of the infected vine.  (However, please note that the presence of leaf roll virus does not always results in immediate loss of crop.) 

If you have both mealybugs and virus infected vines, and have a plan of expansion, it is probably a good idea to protect new vines using insecticides.  However, you have to make sure you have both the virus and mealybugs to justify your action since insecticides for mealybugs are relatively expensive, and as with other chemicals, application of unnecessary insecticide is not recommended.  If it is not properly applied, that extra application of insecticides may results in the outbreak of other insect pests or development of insecticide resistance.

If you are aware of mealybugs, or having a suspicious vines, it is best to submit samples to one of the labs that test vines of viruses.