Controlled testing and breeding for field resistance to potato virus Y

Controlled testing for field resistance to virus Y (placement of viruliferous aphids on plants) was more efficient in insect-proof cages (12×20×6 foot cage covered with 32 gauge Seran) than in the field or greenhouse. Subsequent indexing of the caged clones in the greenhouse gave a good indication of the potential resistance of the clone grown under field conditions.