INFLUENCE OF SIMAZINE OR A STRAW MULCH ON ESTABLISHMENT OF APPLE TREES IN GRASSED DOWN OR CULTIVATED SOIL

The 1st 3 years'' growth of ''Cox''s Orange Pippin'' on M.26 was compared in a trial in which a 4-foot square around the tree received either simazine, or straw mulch, or the same treatment as the surrounding area, which was grass or cultivation. Two rates of Nitrochalk were used. The treatments influenced leaf area and nutrient composition; shoot number, length and weight; and root size and distribution. Competition from a partial weed cover in the 1st year produced a severe growth reduction which persisted in the following years and was not reduced by the higher N rate. A 4-foot square kept weed-free with simazine enabled trees to be grassed in the year of planting and yet make growth comparable to those kept clean-cultivated. Less than 1% of the applied simazine remained active in the soil at the end of the 3rd year. Mulching produced the most vigorous trees. It is considered that soil moisture availability was the main factor influencing tree establishment.