Anthracnose Severity on Annual Bluegrass Infl uenced by Nitrogen Fertilization, Growth Regulators, and Verticutting

Frequency and severity of anthracnose epiphytotics, caused by Colletotrichum cereale Manns Manns sensu lato Crouch, Clarke, and Hillman, on annual bluegrass (ABG) [Poa annua L. f. reptans (Hauskins) T. Koyama] putting greens have increased over the past decade. This 3-yr fi eld study evaluated the impact of N fertilization (4.9 kg ha–1 every 7 or 28 d), mefl uidide (ME; 0 and 0.106 kg a.i. ha–1 yr–1) {N-[2,4-dimethyl-5[[(trifluoromethyl)sulfonyl]amino]phenyl]acetamide}, trinexapac-ethyl (TE; 0 and 0.050 kg a.i. ha–1 every 14 d) [4-(cyclopropyl-α-hydroxymethylene)-3,5-dioxocyclohexanecarboxylic acid ethylester], verticutting (VC; 0and 3-mm depth every 14 d), and interactions of these factors on anthracnose of ABG mowed at 3.2 mm. Nitrogen fertilization frequency had the greatest infl uence on disease throughout the study; N applied at 4.9 kg ha–1 every 7 d reduced damage 5 to 24% compared to a 28-d interval. The plant growth regulators, ME and TE, frequently interacted during the last 2 yr of the study; sequential application of ME and TE reduced disease 6 to 14% compared to plots that only received one of these plant growth regulators. At advanced stages of disease, the combination of 7-d N fertilization and ME and TE application had the greatest disease reduction. Verticutting had little effect on anthracnose severity. Dep. of Plant Biology and Pathology, 59 Dudley Rd., Rutgers Univ., New Brunswick, NJ 08901-8520. New Jersey Agricultural Experiment Station Publication No. D12294-7-07. Received 17 June 2007. *Corresponding author ([email protected]). Abbreviations: ABG, annual bluegrass; ME, mefl uidide; N, nitrogen; PGR, plant growth regulator; PIGE, post-inhibition growth enhancement; TE, trinexapac-ethyl; VC, verticutting; WAT, weeks after treatment. Published in Crop Sci. 48:1595–1607 (2008). doi: 10.2135/cropsci2007.06.0343 © Crop Science Society of America 677 S. Segoe Rd., Madison, WI 53711 USA 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.