The Effect of Phenological Stage on Detectability of Yellow Hawkweed (Hieracium pratense) and Oxeye Daisy (Chrysanthemum leucanthemum) with Remote Multispectral Digital Imagery

Abstract

Many upland pastures and forest meadows in the western United States contain significant infestations of yellow hawkweed and oxeye daisy. Documentation of infestations is necessary in order to plan and assess control tactics. Previous work with an airborne charge coupled device (CCD) with spectral filters indicated that flowering yellow hawkweed with at least 30% cover was detectable at 1 m resolution. A single image of a large area may not capture all plants in the flowering phase and multiple images are costly. The objective of this paper was to assess the accuracy of images recorded at different phenological stages. We compared three methods of classification: unsupervised classification of a three principal component analysis image, supervised classification of a three principal component analysis image, and supervised classification of a composited image consisting of four bands and normalized difference near infrared (NIR)/red band. Regardless of the classification method, images of yellow hawkweed and oxeye daisy in full bloom had lower classification error than at early bloom or post bloom. The percent error for yellow hawkweed classification was about twice as high at post bloom as at full bloom, but varied slightly depending on the method of classification and cover class. The ability to detect discrete colonies of yellow hawkweed was not affected by phenological stage, but the ability to measure the area of each cluster differed among stages. Less than one-third fo the pixels classified as yellow hawkweed or oxeye daisy in the early bloom image remained in the same class in the full bloom image. About half the pixels in the full bloom image remained in the 90 to 100% cover class at the post bloom image. Seasonal growth of the grasses masked some yellow hawkweed and oxeye daisy plants, and accounted for differences in classification among phenological stages.

Remote Distinction of A Noxious Weed (Musk Thistle: CarduusNutans) Using Airborne Hyperspectral Imagery and the Support Vector Machine Classifier

“…Regardless of the reasons, our classification results were consistent with the literature. For example, classification accuracies were better for yellow hawkweed and oxeye daisy (Chrysanthhemum leucanthemum) in full bloom than at early and post bloom stages [77]. In addition, high mapping accuracies were achieved for the peak flowering stage of leafy spurge [60], which indicated that image classification at preflowering and post-flowering stages would have missed some areas occupied by this species because of its similar spectral characteristic with background vegetation.…”

The biology of Canadian weeds. 128. Leucanthemum vulgare Lam.

“…It was utilized in England for treatment of running eyes, cholera, ulcers and "as an application to the secret parts" (Culpeper 1953). L. vulgare infusions are still prescribed by herbalists for treatment of asthma, whooping-cough and nervous excitability, and lotions are recommended for ulcers and sores (le Strange 1977).…”

Mapping Invasive Tamarisk (Tamarix): A Comparison of Single-Scene and Time-Series Analyses of Remotely Sensed Data

“…Similarly, yellow starthistle (Centaurea solstitialis), tamarisk (Tamarix spp. ), yellow hawkweed (Hieracium pratense), oxeye daisy (Chrysanthemum leucanthemum), and Chinese tallow (Sapium sebiferum) also have distinctive colorations that can facilitate remote sensing [22][23][24]. Other species have been detected by their extended growing periods.…”