Abstract
Damage to alfalfa by Acyrthosiphon kondoi Shinji depended on the number of aphids per stem and the length of infestation. In field studies, first-harvest yields were not significantly reduced at populations of 87 aphids per stem, if they were controlled immediately. However, delaying control as few as 8 days at this infestation level resulted in significant yield reductions. These data expand on previous work and set upper levels for aphid infestation. There was no yield loss in the second or third harvest, indicating that no effects carried over from damage sustained before the first harvest. In greenhouse studies, plants subjected to a heavy aphid infestation produced significantly more leaf dry matter but were significantly shorter than noninfested plants. There was no significant difference in quality, as determined by the percentage of protein and total digestible nutrients, between infested and noninfested plants in either the field or greenhouse study.
Published Version
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