The effect of barley yellow dwarf virus infection on agronomic and physiological responses was compared on 10 cultivars of hard red spring wheat (Triticum aestivum L.). The cultivars varied in their agronomic characteristics and in the effect of BYDV on some of these characteristics. The yield of diseased plants was only one‐fourth to one‐half of normal.Healthy plants of all cultivars had essentially the same physiological patterns. Second, fourth, and flag leaf tissues differed in physiological characteristics. Changes in physiology caused by BYDV were greatest in the second Leaf and progressively less in the fourth and flag leaves. Virus infection induced both qualitative and quantitative changes in the interaction between physiological functions. The effect of BYDV infection on physiology was the same for all cultivars. Interrelationships between agronomic characteristics and between physiological functions are presented and discussed. No associations between physiological response and field performance were detected.