Effect of winter inter root-zone temperature on root regeneration of peach rootstocks

Roots of dormant peach trees can grow when soil temperatures are >7 degreesC, which commonly occurs in the southeastern U.S. during the winter. In our tests, root growth on 1-year-old nursery trees was minimal at 7 degreesC, and increased with temperature up to at least 16 degreesC, but rootstocks varied greatly in their regeneration at a given temperature. Trees on seedling rootstocks of 'Guardian(TM)', 'Halford' and 'Lovell' regenerated roots more slowly than those on 'Nemaguard' at soil temperatures >7degreesC. The regeneration rates mirrored the relative susceptibility of these rootstocks to peach tree short life syndrome in the southeastern U.S., which is associated with parasitism by ring nematode.