Detection of Heterodera avenae infestations on winter wheat by radiothermometry

Abstract

This study was an attempt to evaluate the potentialities of radiothermometry for the detection of infestations by the nematode Heterodera avenae Woll. in winter wheat (Triticum aestivum L.) cv. Arminda. Experiments were conducted on two strips after cultivation of resistant (cv. Panema) or susceptible (cv. Peniarth) oat varieties. The infestation levels on the two strips were different. Crops canopy temperature was measured with portable radiothermometers and a thermal infrared camera. The presence of nematodes in the root system markedly increased canopy stomatal resistance during the day. As a result, canopy temperature on a moderately infested plot at midday was higher by approximately 1 "C than on a lowly infested plot. Temperature difference between the two plots greatly varied with time of day, and therefore, cumulative temperature difference appeared to be more useful for detecfing the presence of nematodes. Thermal images allowed precise delimitation of both moderately and lowly infested areas, and thus should be extensively applied to the detection of nematode attacks by remote sensing in large wheat fields. RBSUM~ Détection d'infestations d'Heterodera avenae sur blé d'hiver par radiothennonzétrie Cet article a pour but de définir certaines potentialités de la radiothermométrie pour la détection d'infestations de nématodes (Heterodera avenae Woll.) sur blé d'hiver (Triticunt aestivwn L.) cv. Arminda. Le dispositif expkrimental a été obtenu par culture de variétés d'avoine résistante (cv. Panema) ou hôte (cv. Peniarth). Il comporte deux bandes où les niveaux d'infestation sont différenciés. La température de surface des cultures est mesurée par des radiothermomètres portables et par une caméra infrarouge