Weather factors affect site selection for fruit trees and the choice of varieties. For example, in the northern counties, the average temperatures during the growing season are 2 to 3 degrees lower when compared, by way of example, to East Anglia. This results in a shorter period in which the fruit has to mature and develop its full flavour. The same applies to the West Country; here the rainfall is substantially greater compared with the east of the country.
Some well-known varieties of apple trees are not suitable for high rainfall areas. Other apple tree varieties are very suitable and excel.
Fruit trees and frost
Usually in the UK, winter frosts are not sharp enough to seriously damage fruit trees. It is the spring frosts, particularly in the months of March, April and May, that can seriously diminish crop prospects depending on their severity. The types of fruit that flower earlier compared with apples are most at risk. However in a garden environment it is possible to protect the blossoms from frost damage by covering the trees with a double layer of garden fleece. This should be done in the late afternoon. The fleece has to be opened during the day to provide an entry route for the bees to carry out cross pollination. Watch a video on protecting an apricot tree with fleece.
Fruit trees and drought, wind and hail
Another weather problem is drought. Light sandy soil can cause difficulties. In these cases it is important to apply extra water, weekly, during the growing season. Water must be available to the trees to create new growth and mature ripening fruits.
Strong winds are often the cause of blackened leaves and fruits. Particularly in the more northerly counties and areas close to the sea, consideration should be given to planting a shelter belt to diminish damage to trees and fruit. A walled garden environment is another option. Good staking will be essential for best results.
Hail can be very damaging during the growing season. Avoid planting in areas known as hail belts.
Prolonged periods of rain can be the cause of various fungal diseases such as scab and tree canker. It is best to use varieties with a reasonable level of resistance to these diseases, rather than chemical spraying.
High levels of rainfall can cause problems if they come at a time when large amount of oxygen are needed in the soil. If soil drainage is not efficient in the soil where the fruit trees are planted, the trees can literally drown. Where there is excess water around the roots of the trees, the oxygen-bearing air is driven out of the soil and the roots die. The effect will not be visible immediately. However, as soon as droughty conditions return, the symptoms will be clearly visible: shoot die-back. More seriously, the trees’ immune system will have been damaged. This means the trees will be an easy target for all types of fungal diseases, such as tree canker, armillaria root rot, crown rot, silver leaf, just to name a few.
Fruit trees seem to be able to predict the weather
When we were operating as tree suppliers, over the years we lifted thousands of trees during the winter months, ready to send them to their purchasers. We regularly inspected the roots of these two to three-year old trees. The appearance of the roots gave us an indication of whether the tree was preparing to emerge from dormancy.
A fruit tree’s feeding roots – tiny and delicate capillary roots invisible to the naked eye – operate from April to September. Then they begin to shut down, and the tree stores resources in the trunk and main root stems. At a certain stage, usually in mid January, white roots begin to emerge from the main root stems. These are not functional as roots, but just serve to establish the initial structure from which the feeding roots will develop. It is the arrival of the white roots that show that the tree is reaching the end of its dormancy.
The curious thing is that the exact moment of arrival of the white roots in approximately mid-January, about two months before the end of dormancy, does not depend on the weather conditions up to then, but rather on the weather and temperature in the months to come. It is as if the tree starts preparing for the spring in advance, “knowing” exactly when the temperatures were going to rise, whether in mid-March or early April.
It’s easy to understand the benefits to the trees. There is no point in them developing their root systems in early March if the soil remains icy cold until April. Vice-versa, if the season starts to warm up early, they will benefit if their root system is already in place and functioning.
What’s more mysterious is how the trees are able to detect what the weather will be like a few months later. Perhaps they have a sensitivity to certain meteorological parameters that enable them to time the moment at which to begin preparing for the end of dormancy. The world of plants holds a lot of mysteries that still await scientific explanation.