Recently, the Plant Clinic has received several samples of red maples. Based on the maple samples that we receive, this species seems to have more problems than the other maples. It is not unusual to see dieback and decline in red maple for no apparent reason. On the recent samples, however, there was a yellowing to browning of the interveinal tissues with poor stem growth and overall stunting in the landscape. These samples were found to be free of infectious disease but were diagnosed with chlorosis due to likely manganese deficiency. The same soil conditions of high pH that inhibit iron uptake can also inhibit manganese uptake. Red maples are particularly sensitive to manganese deficiency. For more on chlorosis, refer to the article on pin oak problems in issue No. 9 of this newsletter. Also refer to Report on Plant Disease No. 603.