HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Pethybridge, S. J. Articles by Nutter, F. W. PubMed Articles by Pethybridge, S. J. Articles by Nutter, F. W., Jr. Agricola Articles by Pethybridge, S. J. Articles by Nutter, F. W. Related Collections Other Crop Management Other Crops Plant Disease

Visual and Radiometric Assessments for Yield Losses Caused by Ray Blight in Pyrethrum

^a Tasmanian Institute of Agricultural Research (TIAR), University of Tasmania, P.O. Box 3523, Burnie, Tasmania, 7320, Australia
^b Dep. of Plnat Pathology, University of Wisconsin, Madison 53706, USA
^c Department of Plant Pathology, Iowa State University, Ames, IA 50011
^d Botanical Resources Australia Pty. Ltd., 44-46 Industrial Drive, Ulverstone, Tasmania, 7315, Australia
^e TIAR, University of Tasmania, New Town Research Laboratories, 13 St. Johns Ave., New Town, Tasmania, 7018, Australia

^* Corresponding author (sarah_jp{at}utas.edu.au).

The potential of remote sensing to nondestructively measure relationships between ray blight disease (caused by Phoma ligulicola), plant measurements and components of pyrethrum [Tanacetum cinerariifolium (Trevir.) Sch. Bip.] biomass and yield using a hand-held multispectral radiometer was examined. A range of disease intensities were generated using fungicides in three fields over two years. Nondestructive assessments were obtained by measuring the percentage of sunlight reflected from canopies with a radiometer equipped with five wavelength bands. Combinations of wavelength ratios and four vegetation indices were calculated. Relationships between reflectance and biomass were investigated by removing foliage from the canopy and periodically measuring reflectance. Measurements such as stem height and the number of flowers in October consistently had significant linear relationships with relative pyrethrin and flower yield. The best predictors of relative flower and pyrethrin yield were found using either percentage reflectance in the near infrared (830 nm) and the difference vegetative index (DVI). Sev eral measures had significant linear relationships with fresh weight of foliage, including the near infrared bandwidth and the DVI, which explained 95 to 97% of the biomass variation. This study demonstrated that plant measurements and disease intensity are strongly related to pyrethrin yield, and that remote sensing has great potential to nondestructively obtain preharvest yield and biomass estimates.

Abbreviations: NDVI, normalized difference vegetative index • GNDVI, green normalized difference vegetative index • DVI, difference vegetative index • RDVI, renormalized difference vegetative index • GLAI, green leaf area index

All rights reserved. No part of this periodical may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Permission for printing and for reprinting the material contained herein has been obtained by the publisher.

Received for publication July 18, 2007.