. Bulletin of the Department of Agriculture. Agriculture. BULLETIN OF THE u No. 104: Contribution from the Bureau of Plant Industry, Wm. A. Taylor, Chief July 10, THRIPS AS POLLINATORS OF BEET FLOWERS. By Harry B. Shaw, Assistant Pathologist, Office of Cotton and Truck Diseases and Sugar-Pkmt Investigations. INTRODUCTION. 1 While conducting breeding experiments with sugar beets during a period of more than five years, it could never be observed that the beet flower, despite the pungent fragrance of its nectar and the remarkable abundance of its pollen, attracted nearly as many inse
. Bulletin of the Department of Agriculture. Agriculture. BULLETIN OF THE u No. 104: Contribution from the Bureau of Plant Industry, Wm. A. Taylor, Chief July 10, THRIPS AS POLLINATORS OF BEET FLOWERS. By Harry B. Shaw, Assistant Pathologist, Office of Cotton and Truck Diseases and Sugar-Pkmt Investigations. INTRODUCTION. 1 While conducting breeding experiments with sugar beets during a period of more than five years, it could never be observed that the beet flower, despite the pungent fragrance of its nectar and the remarkable abundance of its pollen, attracted nearly as many insect visitors as numerous blooms offering less pronounced attractions. Especially significant was the rarity of the visits of the honeybee and other common species of Hymenoptera. It appeared as though nature had vainly provided powerful insect lures, excepting only those of conspicuous size and color. It is true that insects, some of them capable of transferring pollen from flower to flower, do visit beet flowers, but relatively their numbers are small and their visits few. breeding experiments necessitated the isolation and hand pollination of numerous beet flowers. Not infrequently, in spite of careful teclmic, it was found that single flowers which had been emasculated and protected by paper bags from pollination became fertilized and produced seed in a manner at the time inexplicable. Although the actual percentage of such cases was small, it was sufficient to attract attention and to cast doubt upon the thorough- ness of the protection afforded by the bags. Not only is the beet flower protandrous, but numerous attempts of the waiter to effect close fertilization by preserving the pollen until the stigma of the same flower should become receptive, then applying the pollen, have failed. The above-mentioned fertilization, therefore, could not have been accomplished by pollen from any one of the single flowers operated on, even had such pollen reached the stigma; in othe
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