Arizona Ragweed pollen is reaching it’s peak this April. Pollen counts are unusually high because of the rainy, wet winter and the windy, warm, dry spring. These conditions are likely to continue through April and most of May. Although the summer heat will put an end to ragweed pollen production in the valley deserts by late May to June, pollen can travel for thousands of miles and so plants growing at higher elevation such as the Catalina Mountains and Mogollon Rim area will affect residents of Phoenix until mid summer.
There are an estimated 41 species of Ragweed found around the world. Many varieties of ragweed are adapted to the arid desert environment with an estimated ten species found in the Sonoran desert. In contrast to ragweed varieties found in the Coastal, Midwestern and Southern regions of the United States, desert varieties of ragweed typically pollinate in the spring rather than late summer to fall.
The most important varieties of ragweed affecting the communities of Chandler, Ahwatukee, Queen Creak, and Tempe, are Rabbit Bush (ambrosia deltoidea), Desert Ragweed (ambrosia dumosa), and Canyon Ragweed (ambrosia ambrosioides). Burro brush pollen (hymenoclea salsola) may cause problems in individuals sensitive to ragweed.