Fruit becomes pale green. Exposed fruit may develop a red blush. Plant part: Shoot. Description: Shoot tips die and shoot growth stops. No new small leaves can be seen emerging from the shoot tip. The dead shoot tip may be visible as a small dead leaf at the base of the last leaf on the shoot. In Michigan, there is typically one flush of growth in the spring, which ends before harvest.
After harvest, some shoots will start growing again, for a second or third growth flush. These later growth flushes usually occur with moist soil conditions and moderate temperatures.
Description: Oldest, largest fruit in the cluster begin to change color from green to pink to blue. Fruit begins to soften. Cell division has stopped and fruit growth is by cell expansion. Description: Single berries in the fruit clusters are ripe and ready to harvest. About ten percent of the fruits, on a bush or in the field, are ready to harvest. This stage is often used to begin the preharvest fungicides for fruit rots.
Description: 25 percent of the berries are ripe. Description: Blueberries are picked several times as the fruit ripens with 2 to 5 pickings. Often the first harvest is by hand and then later by machines that shake berries off the bush.
Shoot growth may begin again. These flower buds form first at the shoot tips. Blueberries are deciduous, shedding their leaves in late fall and early winter. The bare canes of many varieties show hints of red, adding ornamental appeal to the winter landscape.
When identifying blueberries in spring through late summer, look for flowers and fruit. The flowers begin as tear-drop shaped buds, developing into bell-shaped flowers in clusters of 5 to 10 blooms. Many blueberry varieties have white flowers, but some cultivars have pink blossoms.
Once the flowers fade, clusters of small green berries appear, gradually turning red then blue as they ripen on the bush. Depending on the variety, blueberries produce from early summer through late fall. Blueberries are traditionally grown in northern climates with cold winters, but horticulturalists have developed varieties for warmer climates.
To create a variety suitable for warm climates, the standard highbush blueberry Vaccinium corymbosum , hardy in USDA zones 3 through 7, is crossed with the southern wild variety rabbiteye V.
Once buds leave dormancy stage 2 , they progress, more or less, depending on heat units accumulated. So, on cold days buds advance very little, but when it warms up buds advance very fast. Also, buds over the whole plant are at many different stages at once Fig.
Therefore, one cannot simply designate a single stage to describe a whole plant or especially whole fields. These data remind us that although there are some variety differences in cold hardiness and typically highbush varieties are more cold hardy than rabbiteye , overall, as flower buds advance they become more sensitive to freezing temperatures.
Hopefully this review helps to remind us about the progression of flower buds, and the fact that floral bud stages are good indicators for communicating what is happening with regards to plant development. Figure 1. Various flower bud stages occur simultaneous over the entire plant and field. Looking closely, flower bud stages 2 through 6 can be seen on this one plant.
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