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

This Article 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 Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Wierma, D. W. Articles by Grau, C. R. Search for Related Content PubMed Articles by Wierma, D. W. Articles by Grau, C. R. Agricola Articles by Wierma, D. W. Articles by Grau, C. R.

Root Heave of Alfalfa Cultivars with Differing Levels of Resistance to Aphanomyces Root Rot

Agric. Res. Stn., 8396 Yellowstone Dr., Marshfield, WI 54449
Dep. of Agronomy, Univ. of Wisconsin, Madison, WI 53706
Dep. of Plant Pathology, Univ. of Wisconsin, Madison, WI 53706

^* Corresponding author (dwiersma{at}facstaff.wisc.edu).

Aphanomyces root rot (ARR) (caused by Aphanomyces euteiches Drechs.) and phytophthora root rot (PRR) (caused by Phytophthora sojae M.J. Kaufmann & J.W. Gerdemann) are important diseases of alfalfa (Medicago sativa L.) grown in wet soil, but few studies have quantified the effects of ARR on alfalfa performance. An alfalfa cultivar trial of 82 cultivars with differing levels of ARR resistance was seeded in July 1993 in a naturally infested soil at Marshfield, WI. Excessive precipitation in 1993 and 1994 led to widespread expression of ARR and PRR, and large cultivar yield differences were measured. There was differential root heaving among cultivars in the 1993–1994 winter. Fall 1993 forage yield was low, but cultivars with high ARR resistance yielded >400% more than did susceptible cultivars. Root heaving in 1994 was inversely correlated with level of resistance to ARR (r = –0.68), 1993 forage yield (r = –0.72), and 1994 forage yield (r = – 0.81). Resistant and highly resistant cultivars produced 2 Mg ha^–1 more forage than susceptible or low resistance cultivars. Forage yields in 1995 (a relatively dry year) did not differ with ARR resistance level. Under wet soil conditions, ARR-resistant alfalfa cultivars can produce higher forage yields than susceptible cultivars. In addition, resistance to ARR reduces damage due to root heaving.

Received for publication February 26, 1996.