Overcrowded trees may be the number one cause of decreased nut production in older orchards through the southern United States. As trees become crowded and limbs begin to touch, nut production goes down dramatically. This is because trees are competing for a limited supply of water, nutrients and sunlight. Opening up space between trees by thinning reduces root zone competition and sunlight blockage. Open space between trees also makes application of pesticides for insect and disease control more efficient.