Growth Regulators and Irrigation Mitigate Competition Between Intercropped Grass and Fraxinus nigra ‘Fallgold’

Abstract Grass, intercropped with nursery stock, is beneficial to the long-term productivity of a field due to decreased erosion of topsoil and increased soil organic material. The primary disadvantage of using grass as an intercrop is supposedly due to a reduction in nutrients and water available to nursery stock. In the spring of 1999, Fraxinus nigra ‘Fallgold’ trees were planted in herbicide strips with no intercrop (cultivated soil), an intercrop of untreated ryegrass, an intercrop of mowed ryegrass or an intercrop of ryegrass treated with a growth regulator. Half of the trees in each treatment were irrigated and half were not. Growth measurements were taken over two, growing seasons. There were no significant increases in growth with the addition of irrigation with the exception of trees grown with an intercrop of growth regulated ryegrass where the addition of irrigation resulted in greater tree height. Trees grown with no intercrop had the greatest increase in both caliper and height. Trees grown w...