Summer pruning is also often used to remove fireblight infected wood. Growers should be very careful with this operation. Evidence is that the fireblight bacterium may be found in phloem considerable distances below the bottom of the visible infection lesion. Be aware that the disease may be spread by summer pruning. Summer pruning by removing a few selective limbs may improve light penetration into the tree canopy and improve return bloom for next season.
Fruit trees form flower buds for next year's crop in the first half of the previous growing season.
In other words, buds developing in fruit trees this May and June will be next year's crop. The response to pruning varies with the time of pruning. Late season summer pruning may not have any effect on next year's crop but may delay the onset of fall dormancy making the tree susceptible to early winter injury. Pruning 4 to 6 weeks before apple harvest may improve fruit color while earlier pruning may not have a significant effect on fruit color. Pruning in the last 4-6 weeks during the season may result in sunburn injury as the fruit are not potentiated to direct, intense solar irradiation.