Reduction in the yield and viability of carrot seed in relation to the occurrence of the plant bug Lygus campestris L.

Summary Research was carried out into the cause of a disorder occurring in seed plants of carrots characterized by backward fruits and resulting in a reduced seed yield.It appeared that both fertilization and initial development of the endosperm and embryo were normal, but that later on a sudden check in the growth of the fruit occurred, accompanied by disintegration of the contents of the ovule.Bugs of the species Lygus campestris L. were found to occur in considerable numbers on the seed plants of carrots. In experiments a reduced seed production with the same macroscopic and microscopic symptoms could be obtained when bugs were added to caged carrot umbels.It could be established that the presence of bugs caused not only a reduction in the seed production due to abortion of endosperm and embryo, but also a reduction in the germination percentage of the full-grown seeds due to embryolessness.When the bugs were brought on the umbels before or during anthesis the reduction in seed viability and expecially the reduction in seed production proved to be more serious than when the bugs were added after anthesis.