Reflective mulch (Extenday™) in plum orchards (Prunus domestica L.) preliminary results

In an orchard planted with seven-year-old trees of plum cultivars 'Excalibur' and 'Prinlewl grafted on the rootstock 'Saint Julien A', the grass strips between the tree rows were covered with white, reflective ground cover to improve the light regime. Uncovered trees without reflective ground cover served as controls. The grass strips were covered from two weeks after bloom throughout the whole growing season until harvest in mid September. The surface colour and the content of soluble solids were lower and the ground colour greener in fruits harvested in the lower part compared to the upper part of the branch canopies of trees grown without reflective mulch. Where reflective cover had been applied, the fruits from the lower canopy part were not significantly different from the fruits in the upper part in their colouration, amount of titratable acidity and fruit firmness. The content of soluble solids was lower in the lower canopy fruits compared to those harvested from the upper part of these trees. Applying reflective mulch in plum orchards gave more even maturity of the fruits in the lower and upper parts of the trees. Hence, fewer pickings in reflective mulch treated trees will be required. The temperature in the trees was not increased. The cover reduced the growth of the grass sod in the alleyways.