The study looked at why some almond trees fail to produce buds without any infection. They found that trees from the same source can have different rates of bud-failure in different orchards, with hotter areas showing more severe symptoms. The conditions in the nursery can slightly affect the trees' susceptibility, but the orchard location has a bigger impact. Changing the temperature can turn symptomless trees into bud-failure ones, but going back to a lower temperature doesn't reverse the susceptibility, although symptoms might not show.