Gordon Johnson, Extension Fruit & Vegetable Specialist; gcjohn@udel.edu
Research has shown that peach tree pruning is best done in March or April.
In past years with mild winters, there has been a tendency to prune on the early side. With the snow and cold weather in 2010 this has not been as much of an issue this year.
Pruning is done to remove suckers, manage fruit loads, manage vigor, manage tree shape, increase light penetration, and remove damaged or weak wood.
Pruning earlier than March increases the risk of cold injury to buds because trees are stimulated metabolically by the pruning. It is advised to only do pruning to remove dead or damaged wood during the winter.
As trees start to become active in March, there is little or no increase in cold injury to buds by pruning. Sucker removal and removal of weak fruiting branches can be done at this time, along with managing the shape and openness of the tree. While selective removal of excess fruiting material can be done, the full fruiting potential cannot be evaluated until plants start to bloom. In addition, winter injury or poor plant vigor cannot be determined accurately in March. This may lead to excessive pruning of weaker trees that could be detrimental.
You can also prune peaches when plants start to bloom through the month of April. This allows for better assessment of fruiting potential and selective thinning of fruiting wood to manage crop loads. It also stimulates plants to produce more growth. In peach orchards where reduced plant vigor or damage is suspected, delaying pruning to late April or early May will allow for accurate assessment of tree status so that pruning can be matched to the level of vigor or extent of damage.
Summer pruning (July) can be beneficial, especially in trees with excessive growth. However, because peaches fruit the following year on wood produced this year, any removal of this year’s growth will reduce fruiting wood for next year. Therefore, take care not to do excessive summer pruning. August pruning is not recommended on trees still in fruit but can be done on earlier cropped trees or non-bearing trees.
Avoid peach pruning from September through February and mid-May through June.
For a good article on the subject by Jerome Frecon, Agricultural Agent at Rutgers University, go to http://njaes.rutgers.edu/pubs/plantandpestadvisory/2009/fr0113.pdf.