| ![Plant zone hardiness map](/ARSUserFiles/80000000/USDAHistoryExhibit/1990_1t.jpg) | The first Plant Hardiness Zone Map for the U.S., accurate to the county level, is released.
Studies find trans fatty acids in margarine can increase people's cholesterol levels. In addition, a study finds eggs to have 20% less cholesterol than previously thought. |
![Return to top of page](/ARSUserFiles/80000000/graphics/nav/up.gif) | ![Photo: Laser microscope for separating sperm](/ARSUserFiles/80000000/USDAHistoryExhibit/1990_5t.jpg) | Technology to separate X and Y bearing sperm of animals is developed to allow sex selection of offspring.
After years of research and misidentification, the cause of corn stunt disease, spiroplasma, is discovered to be the first known representative of an entirely new type of plant pathogen. |
![Return to top of page](/ARSUserFiles/80000000/graphics/nav/up.gif) | ![Photo: Researcher with honey bee hives](/ARSUserFiles/80000000/USDAHistoryExhibit/1990_6t.jpg) | A gel formulation of formic acid is developed to control parasitic mites of honey bees.
Land is provided for the construction of the George Washington Carver Center which houses many USDA administrative offices. |
![Return to top of page](/ARSUserFiles/80000000/graphics/nav/up.gif) | ![Poster: Food guide pyramid](/ARSUserFiles/80000000/USDAHistoryExhibit/1990_7t.jpg) | The Food Guide Pyramid is developed by USDA, using Beltsville research. The Nutrient Database is enhanced with information on more than 100 nutrients of 7,300 foods.
More precise roles of nutrients are discovered such as selenium, which reduces the effects of malaria, and chromium picolinate and chromium nicotinate, which lower blood pressure in hypertensive rats. |
![Return to top of page](/ARSUserFiles/80000000/graphics/nav/up.gif) | ![Photo: Cryopreservation (ultra-low-temperature storage) of livestock empryos](/ARSUserFiles/80000000/USDAHistoryExhibit/1990_9t.jpg) | Ultra-low temperature storage, cryopreservation, of swine embryos is developed enabling unprecedented global transport of embryos.
SoilGard, the first biocontrol agent for soil-borne diseases, and neem-based products for controlling both fungal diseases and insects pests are developed. |