Tucson Pollen Today and Tomorrow - September

Pollen and mold counts are increasing.  It is possible that he fall hay fever season will be less active this year because of the low rainfall during this summer's monsoon.  Expect new growth of  many weeds including  Salsola (Russian Thistle or Tumbleweed) and Amaranthus palmeri (Carelessweed).  Carelessweed and Russian Thistle are flowering already, and Slimleaf Bursage (Ambrosia confertiflora) is starting to form flowers.  However, the more important ragweeds  Ambrosia ambrosiodes (canyon ragweed) and  Ambrosia deltoidea (triangle leaf bursage, rabbit bush) are not flowering at this time.  Grasses have also been growing and flowering for several weeks.  Pennisetum ciliare (Buffel Grass) is flowering, particularly at county roadsides.   Bermuda grass (Cynodon dactylon) established in alleys and roadsides has greened up and is releasing pollen.  Other grasses such as Pennisetum setaceum (Fountain Grass) and Eragrostis Lehmanniana (Lovegrass), are growing and flowering now.  The moist warm soil and higher humidity is causing some mold growth, but with the exception of puffball fungi, airborne spores will not become a problem until after the monsoon is over and the surface layers of soil begin to dry up.

Note:  This information is based on ongoing observation of flowering allergenic plants in the Tucson metropolitan area, and not on pollen counts.   Appearance and persistence of any particular airborne pollen species in the air usually lags behind the onset of flowering of the plant of origin.                                                                        Back

Disclaimer:   This site is for educational purposes only.  Any information that you have found in this web site is not intended to replace medical care or advice given to you by your own physicians. You should consider consulting your local medical library and other web sites for additional information. 

Comments and suggestions welcome!   Email: schumach@u.arizona.edu
Content Owner:  Michael J. Schumacher, MB, FRACP, The University of Arizona
Updated 9-3--2009