Abstract: Methods and systems for assessing plant conditions by volatile detection. The subject matter of the present disclosure describes a cost-effective, compact, noninvasive volatile organic compound (VOC) fingerprinting platform installed on a consumer electronics device such as a smartphone, tablet, or handheld device, or other mobile device for the early detection and/or diagnosis of disease in a plant caused by infection by a plant pathogen such as Altemaria solani, Septoria lycopersici, or Phytophthora infestans, based on the pattern analysis of characteristic leaf volatile emissions. This handheld device integrates a sensor array to be imaged by the smartphone camera and a micropump for active sampling and real-time detection.