ORCHARD FLOOR CROPS REDUCE GROWTH OF YOUNG PECAN TREES

Hairy vetch (Vicia villosa Roth), common vetch (V. sativa L. 'Cahaba W hite'), arrowleaf clover (Trifolium vesiculosum Savi 'Yuchi'), crimson clover (T. incarnatum L. 'Tibbee'), red clover (T. pratense L. 'Redla nd II'), yellow nutsedge (Cyperus esculentus L.), buckwheat (Fagopyrum sagittatum Gilbert),hairy indigo (Indigofera hirsuta L.),bahiagrass ( Paspalum notatum Flugge 'Pensacola'), common bermudagrass [Cynodon dac tylon (L.) Pers.], and centipedegrass [Eremochloa ophiuroides (Munro) Hack] were grown for 3 years in a 3 x 3-m spacing around young pecan [ Carya illinoinensis (Wangenh.) K. Koch] trees. Compared to weed-free p lots, all cover crops suppressed tree growth substantially, and there were no differences among cover crops in the degree of suppression. Me an trunk cross-sectional area of weed-free trees increased 26-fold by the end of the third growing season but increased only 13-fold for tre es grown with any cover crop. These results suggest that cover crops, if grown in young pecan orchards to promote beneficial insects, should be excluded from the immediate area around the young trees.