According to the Asthma and Allergy Foundation of America, about 75% of Americans who have plant allergies are sensitive to ragweed. You’ll find common ragweed sprouting in the fields and roadsides, riverbanks, and throughout rural areas of Texas. Ragweed pollen season begins in mid-summer and continues through the middle of November. Species of ragweed account for most of the hay fever reactions experienced in the fall months. Symptoms include sneezing and runny nose, as well as itchy eyes.