Cultivar and Management Effects on Stand Persistence of Birdsfoot Trefoil

Interactions between growth habit and management of birdsfoot trefoil (Lotus corniculatus L.) are reported by other researchers to affect stand persistence. Stand persistence dependent on the longevity of plants within the stand can be confused with the persistence of stand resulting from natural reseeding in this crop. A field test of 10 birdsfoot trefoil cultivars differing in growth habit was planted in May 1979 on Mexico silt loam (Fine, montmorillinitic, mesic Udollic Ocharqualf) near Columbia, Mo. Commencing April 1980, effects of four management treatments on stand persistence were studied to determine the degree of emphasis to be given to growth habit in a program of genetic improvement for trefoil persistence. Volunteer seedling establishment was controlled with simazine [2-chloro-4,6-bis(ethylamino)-s-triazine]. Significantly lower herbage yields in stockpiled and unharvested managements were attributed to foliar blight caused by Rhizoctonia solani Keuhn. Stand persistence, based on plant counts, was observed to be independent of management since plants within stands behaved more like biennials than perennials regardless of management. Cultivar by management effects on stand persistence were not significant (P>0.05). An average stand reduction of 90% was observed from April 1980 to 1982. Greatest reductions in stand counts were observed each year between April and October. An average disease score of 2.4, where 0 indicated root and crown tissues visibly free of decay and 5 indicated extensive decay, was obtained from 939 surviving plants examined in April 1982. Poor stand persistence could be explained in part by the foliar, crown, and root diseases found at the study site. Lack of differences in stand persistence and tolerance to disease may reflect the close ancestry of the entries tested. Emphasis on growth habit in a genetic improvement program for persistence in the Southern Corn Belt appeared less important than an examination of genetic resources for lowered susceptibility to disease.