Controlling weeds using chemicals is very widespread. The introduction of the herbicide Velpar in 1982 (in Canada) or 1983 (in the United States) is credited with being the single most important reason for the increase in yields of wild blueberries during the second half of the 1980s.
Applied in the spring following pruning, it proved very effective in killing almost all the weeds competing with the crop, including those that bear berries that would become mixed in with the blueberries and spoil the picked product.
In addition to reducing competition and allowing the wild blueberries space to gradually spread into spaces formerly occupied by weeds, chemically based weed control has also meant that fertilizer can be used more effectively.
Instead of encouraging the weeds to flourish above all else, the minerals go exclusively into the roots of the blueberries, which in turn increases the plant’s growth in this first year of the biennial cycle.
It is in the first year that the framework for the production of flowers – and therefore the fruit in the following year – is established.
Growth starts in April and if a balanced fertilizer is used, it is applied just before then. Blueberries that are left unpruned are in the second year of the cycle.
They will yield fruit provided there has been damaged to the dormant buds at the tips of the previous year’s growth during the winter, and provided late frosts do not damage the potential flowers as they develop from those buds.
As might be expected, pest and disease problems occur in areas where there is a concentration of a single species. Mummyberry may appear and this can be controlled using an approved fungicide as the blueberry buds break into life in spring on the areas due to crop.
Blueberry spanworm can be a problem and this pest is controlled by using a biological method.
A spray containing a bacterium (bacillus thuringiensis) destroys the moth “worms” or larvae. Unlike most insecticides, it is harmless to bees. If larvae of the blueberry fruit fly is burrowing into the fruit and spoiling its quality, then an insecticide spray may have to be used.
The timing of the application of this spray is crucial because it has to kill the pest while leaving no residue by the time the fruit is ripe and ready for harvest.
Use of Chemical
