Articles
Sooty mold alterations in photosynthesis and leaf chlorophyll in ‘Natchez’ crepe myrtle (Lagerstroemia indica × fauriei ‘Natchez’) infested with crepe myrtle bark scale (Acanthococcus lagerstroemiae)
Article number
1467_20
Pages
173 – 178
Language
English
Abstract
Crepe myrtle bark scale (CMBS) (Acanthococcus lagerstroemiae) is an important crepe myrtle (CM) pest and causes the development of sooty mold (SM). To evaluate changes in photosynthesis related to sooty mold, measurements were taken on locally planted crepe myrtles.
The first population was at the East Texas A&M University Crepe Myrtle Research Garden (CMRG) that includes 24 ‘Natchez’ crepe myrtle (Lagerstroemia × fauriei ‘Natchez’) divided equally across four blocks.
The second location was a local planting with 12 ‘Natchez’ trees, all CMBS free.
Six trees were chosen at the CMRG, selecting those with both sooty mold leaves (SM) and new, sooty mold-free leaves (New). At the local site, six trees were selected with mature, but sooty mold-free leaves (Mature). We used a fluorometer/porometer (LI-600, Li-Cor Environmental, Lincoln, NE) to measure stomatal conductance (gsw), leaf vapor pressure deficit (VPDleaf), quantum yield (ɸPSII), and electron transport rate (ETR) on five leaves from each tree.
Five leaves from each tree were selected to measure net photosynthesis (Anet), and one leaf per tree was selected for a light response curve, both using a portable photosynthesis meter (LI-6800, Li-Cor Environmental, Lincoln, NE). A SPAD meter was used to estimate leaf chlorophyll content.
Across all trees, Anet was higher in new (11.6 µmol m‑2 s‑1) and mature leaves (10.1 µmol m‑2 s‑1), compared to SM leaves (6.9 µmol m‑2 s‑1), with Anet also higher at all light intensities above 50 µmol m‑2 s‑1. New leaves had lower SPAD readings (35.7), while Mature and SM leaves were higher, 51.3 and 54.0, respectively.
Leaf condition had no impact on gsw, VPDleaf, or ETR, but ɸPSII was higher in SM leaves (0.66), followed by New (0.57), and lowest in mature (0.31). It appears that SM leaves are compensating, but the presence of sooty mold has an important, negative impact on net photosynthesis, emphasizing the importance of CMBS control.
The first population was at the East Texas A&M University Crepe Myrtle Research Garden (CMRG) that includes 24 ‘Natchez’ crepe myrtle (Lagerstroemia × fauriei ‘Natchez’) divided equally across four blocks.
The second location was a local planting with 12 ‘Natchez’ trees, all CMBS free.
Six trees were chosen at the CMRG, selecting those with both sooty mold leaves (SM) and new, sooty mold-free leaves (New). At the local site, six trees were selected with mature, but sooty mold-free leaves (Mature). We used a fluorometer/porometer (LI-600, Li-Cor Environmental, Lincoln, NE) to measure stomatal conductance (gsw), leaf vapor pressure deficit (VPDleaf), quantum yield (ɸPSII), and electron transport rate (ETR) on five leaves from each tree.
Five leaves from each tree were selected to measure net photosynthesis (Anet), and one leaf per tree was selected for a light response curve, both using a portable photosynthesis meter (LI-6800, Li-Cor Environmental, Lincoln, NE). A SPAD meter was used to estimate leaf chlorophyll content.
Across all trees, Anet was higher in new (11.6 µmol m‑2 s‑1) and mature leaves (10.1 µmol m‑2 s‑1), compared to SM leaves (6.9 µmol m‑2 s‑1), with Anet also higher at all light intensities above 50 µmol m‑2 s‑1. New leaves had lower SPAD readings (35.7), while Mature and SM leaves were higher, 51.3 and 54.0, respectively.
Leaf condition had no impact on gsw, VPDleaf, or ETR, but ɸPSII was higher in SM leaves (0.66), followed by New (0.57), and lowest in mature (0.31). It appears that SM leaves are compensating, but the presence of sooty mold has an important, negative impact on net photosynthesis, emphasizing the importance of CMBS control.
Authors
D.A. Harp, M. Coyle
Keywords
crepe myrtle, Lagerstroemia indica, crepe myrtle bark scale, Acanthococcus lagerstroemiae
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