Sooty Mold Fungus on Pecan Foliage Suppresses Light Penetration and Net Photosynthesis

Abstract

The heavy levels of sooty mold commonly present on pecan [ Carya illinoensis (Wangenh.) C. Koch] foliage in the autumn prompted an evaluation of its influence on net photosynthesis (Pn) of pecan leaves. Extra heavy sooty mold levels were observed to block light penetration to the leaf surface by up to 98%. Heavy mold levels suppressed leaflet Pn by up to 70% with suppression due to a blockage of photosynthetically active radiation (PAR). An observed 4°C increase in abaxial leaf surface temperature may also contribute to this suppression. The results indicate a possible need to introduce sooty mold control methods into orchard management programs.