caa a22 4500 445864664 CHVBK 20180317145454.0 cr unu---uuuuu 170323e20111001xx s 000 0 eng 10.1007/s11119-010-9212-3 doi (NATIONALLICENCE)springer-10.1007/s11119-010-9212-3 Thermographic assessment of scab disease on apple leaves [Elektronische Daten] [E.-C. Oerke, P. Fröhling, U. Steiner] Phytopathogenic fungi may affect both the cuticular and the stomatal conductance of plant tissue resulting in significant modifications of leaf temperature. Venturia inaequalis colonizes apple leaves below the cuticle (subcuticularly) causing scab disease. The suitability of digital infrared thermography for sensing and quantifying apple scab was assessed by investigating the effects of V. inaequalis on the water balance of apple leaves in relation to the disease stage and the severity of scab. Transpiration was measured by infrared thermo-imaging to evaluate spatial heterogeneity of the leaves in response to localized infections. Fungal development was assessed microscopically. Subcuticular growth of the pathogen caused localized decreases in leaf temperature before symptoms appeared that significantly increased the maximum temperature difference (MTD) of leaves. The MTD increased with scab development and was strongly correlated to the size of infection sites (r²linear=0.85) and overall disease severity (% diseased leaf area, r²square=0.71). In later stages of the disease, the MTD decreased because of leaf senescence. Thermographic measurements revealed differences in disease severity resulting from disease stage, resistance of host tissue and differences in the aggressiveness of V. inaequalis isolates. Subcuticular growth of the pathogen was beyond the area of conidia production, therefore, the area of leaf with increased transpiration was larger than the scab lesions; the proportion decreased from >70% in the early stages to <20% for mature lesions. Leaf transpiration was increased by all stages of scab development, therefore, MTD may be used not only for the differentiation between diseased and non-diseased leaves, but also for disease quantification, e.g. in screening systems and monitoring in precision agriculture. Springer Science+Business Media, LLC, 2010 Apple scab nationallicence Remote sensing nationallicence Disease quantification nationallicence Thermal imaging nationallicence Transpiration rate nationallicence Venturia inaequalis nationallicence Oerke E.-C Institute of Crop Science and Resource Conservation (INRES)—Phytomedicine, University of Bonn, Nussallee 9, 53115, Bonn, Germany aut Fröhling P. Institute of Crop Science and Resource Conservation (INRES)—Phytomedicine, University of Bonn, Nussallee 9, 53115, Bonn, Germany aut Steiner U. Institute of Crop Science and Resource Conservation (INRES)—Phytomedicine, University of Bonn, Nussallee 9, 53115, Bonn, Germany aut Precision Agriculture Springer US; http://www.springer-ny.com 12/5(2011-10-01), 699-715 1385-2256 12:5<699 2011 12 11119 https://doi.org/10.1007/s11119-010-9212-3 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s11119-010-9212-3 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Oerke E.-C Institute of Crop Science and Resource Conservation (INRES)—Phytomedicine, University of Bonn, Nussallee 9, 53115, Bonn, Germany aut NATIONALLICENCE 700 1- Fröhling P. Institute of Crop Science and Resource Conservation (INRES)—Phytomedicine, University of Bonn, Nussallee 9, 53115, Bonn, Germany aut NATIONALLICENCE 700 1- Steiner U. Institute of Crop Science and Resource Conservation (INRES)—Phytomedicine, University of Bonn, Nussallee 9, 53115, Bonn, Germany aut NATIONALLICENCE 773 0- Precision Agriculture Springer US; http://www.springer-ny.com 12/5(2011-10-01), 699-715 1385-2256 12:5<699 2011 12 11119 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer