Apple trees that have not been pruned for several years can pose challenges, according to University of Illinois Extension local food systems and small farms educator Maurice Ogutu.
"Most apple trees planted before the semi-dwarf or dwarfing roots were available were standard trees that were grafted onto seedling rootstocks," said Ogutu. "These types of trees tend to grow taller and have longer branches leading to shading of many shoots, particularly the lower branches.
"In such types of trees, larger fruits are borne mainly on the top part of the tree that receives sunlight. Smaller, misshapen fruits are borne in the shaded parts of the tree. The misshapen fruits may be due to disease and insect pest damage. In order to rejuvenate these trees and increase fruit production, the trees need to be pruned so that all the branches and shoots have good sunlight exposure."
Pruning is the judicious removal of shoots and branches for the benefit of the tree. A pruned tree will have good sunlight exposure to all the branches, will be of a manageable size, have branches with wider crotch angles that support fruit load, have good spray coverage to all shoots, and bear good-quality fruit every year, Ogutu said.
In northern Illinois, pruning is done between Feb. 15 and April 1 when the trees are still dormant. Pruning mature neglected apple trees can be started earlier in winter when the tree is still dormant. Pruning can be done with simple tools such as hand pruners for small shoots and spurs. Larger shoots can be removed using lopping shears or a pruning saw.
Pruning neglected trees is done more severely, compared to the trees that are pruned yearly.
"Generally apples bear fruit on spurs that arise from branches that are more than one year old," he said. "The first step in pruning neglected apple trees is to remove any dead, diseased shoots or branches on the tree. The second step is to prune upward-growing shoots such as water sprouts and branches that shade the lower branches.
"The third step is to prune downward-growing shoots as these shoots are very close to the ground, and when they become heavy with fruit, it may lead to fruits lying on the ground. This will also interfere with weed control, particularly when mowing. It is suggested that the lowest branch needs to be at least 3 feet from the ground. The fourth step is to prune shoots and branches that are crossing because these shoots will whip and bruise the fruits, and some will be rubbing onto the other shoots."
After eliminating all the crossing branches, look at the tree to check if there are shoots that shade other branches and prune them. The final step is to prune shoots that grow around the base of the tree trunks called suckers as these are the areas that insects are going to hide in and cause damage to the tree and fruits.
"Once the tree is rejuvenated, only moderate pruning should be done annually during the dormant season, and in order to produce good-quality fruit, timely spraying to control insect pests and diseases is necessary," he said.
Source: Maurice Ogutu, Extension Educator, Local Food Systems and Small Farms, firstname.lastname@example.org
Pull date: April 1, 2012